- Living Anionic Polymerization of N-(1-Adamantyl)-N-4-vinylbenzylideneamine and N-(2-Adamantyl)-N-4-vinylbenzylideneamine: Effects of Adamantyl Groups on Polymerization Behaviors and Thermal Properties
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The anionic polymerization of N-(1-adamantyl)-N-4-vinylbenzylideneamine (1) and N-(2-adamantyl)-N-4-vinylbenzylideneamine (2) was performed using various initiators, such as oligo(α-methylstyryl)dipotassium, potassium naphthalenide, diphenylmethylpotassium, and diphenylmethyllithium, in THF at -78°C for 1 h to investigate the effects of adamantyl groups on the polymerization behaviors and thermal properties of the resulting polymers. The well-defined poly(1) and poly(2) with predictable molecular weights and narrow molecular weight distributions were successfully obtained, indicating that the bulky adamantyl groups effectively protected the carbon-nitrogen double bond (Ci=N) from the nucleophilic attack of the initiators and the propagating chain ends. The stability of the propagating chain end of poly(1) was confirmed by the quantitative efficiencies in the postpolymerization and the sequential copolymerization with tert-butyl methacrylate. A poly(4-formylstyrene) was quantitatively formed by the acidic hydrolysis reaction of the N-adamantylimino groups of the poly(1). The resulting poly(1) and poly(2) showed significantly high glass transition temperatures (Tg) at 257 and 209°C, respectively, due to the bulky and stiff adamantyl substituents. It was also found that the substituted position of adamantane unit and the linkage between polystyrene backbone and adamantyl groups played very important roles to determine the Tg values of the substituted polystyrenes.
- Kang, Beom-Goo,Shoji, Hideo,Kataoka, Hiroshi,Kurashima, Reo,Lee, Jae-Suk,Ishizone, Takashi
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Read Online
- Antibiotic protected silver nanoparticles for microbicidal cotton
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Surface coating of metal nanoparticles is one of the major aspects to be optimized in the design of antimicrobial nanoparticles. The novelty of this work is that antimicrobial derivatives have been used as stabilizers to protect silver nanoparticles (Ag NPs). Microbicidal activity studies of fabricated cotton textiles coated with these Ag@Antibio were performed. Protective ligand layers of Ag NPs resulted to be a deterministic factor in their antimicrobial activity. The best bactericidal activity was obtained for Fabric TAM (coated with Ag NPs with triarylmethane derivates in surface, Ag@TAMSH), with a bacterial decrease of 3 log units for the S. aureus strain. Intrinsic antibiotic activity and partial positive charge of the TAMSH probably enhanced their antimicrobial effects. Fabric Eu (coated with Ag NPs with eugenol derivates in surface, Ag@EugenolSH) and Fabric FQPEG (coated with Ag NPs embedded in PEG-fluoroquinolone derivatives in surface, Ag@FQPEG) displayed antibacterial activity for both Staphylococcus aureus and Pseudomonas aeruginosa strains. These coated antimicrobial cotton fabrics can be applied in different medical textiles.
- Montagut, Ana Maria,Granados, Albert,Ballesteros, Anna,Pleixats, Roser,Llagostera, Montserrat,Cortés, Pilar,Sebastián, Rosa María,Vallribera, Adelina
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Read Online
- Oxoammonium Salt-Mediated Regioselective Vicinal Dioxidation of Alkenes: Relying on Transient and Persistent Nitroxides
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A novel, easy-to-handle, and regioselective vicinal dioxidation of alkenes under transition metal and organic peroxide free conditions has been developed. This approach uses N-hydroxyphthalimide and its analogues as the transient nitroxyl-radical precursors and 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (TEMPO+BF4-) as the oxidant as well as the source of persistent nitroxide. By employing this method, multifarious structurally important dioxidation products were efficiently synthesized from simple alkenes and complex bioactive molecule derivatives.
- Chen, Fei,Ge, Ming-Jing,Liu, Shi-Yu,Wu, Lu-Yan,Yang, Hao,Yang, Qing-Yun,Zheng, Yang,Zhu, Xin-Yue
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supporting information
p. 8533 - 8538
(2021/11/17)
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- Preparation method of cyclic carbonate
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The invention belongs to the technical field of materials, and particularly relates to a preparation method of a cyclic carbonate, which takes a double-center porous polymer as a catalyst and catalysis CO. 2 The conversion is cyclic carbonate, and the double-center porous polymer is a double-center heterogeneous porous catalyst of metalloporphyrin and quaternary phosphonium sites. The invention solves the problem of complicated recovery of the catalyst for synthesis of the existing cyclocarbonate, utilizes the double-center porous polymer containing the metalloporphyrin and the quaternary phosphonium site as a catalyst to realize the combination and synergistic combination of the two active centers on the molecular level, thereby efficiently converting carbon dioxide into cyclic carbonate.
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Paragraph 0029; 0034-0035
(2021/11/03)
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- Double-center porous polymer and preparation method thereof
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The invention belongs to the technical field of catalysts, and particularly relates to a double-center porous polymer, a preparation method thereof, a porphyrin and 4 - (diphenylphosphino) styrene monomer which are functionalized by vinyl, and are prepared by quaternary phosphonium and metal coordination. The invention solves the defect that an existing porous catalyst structure is not easy to regulate and control, utilizes metalloporphyrin and quaternary phosphonium sites as an active center and is fixed in a porous polymer to form a double-center heterogeneous porous catalyst.
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Paragraph 0025; 0032-0033
(2021/11/21)
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- Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Vinyl Acetate in Dimethyl Isosorbide as a Sustainable Solvent
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A nickel-catalyzed reductive cross-coupling has been achieved using (hetero)aryl bromides and vinyl acetate as the coupling partners. This mild, applicable method provides a reliable access to a variety of vinyl arenes, heteroarenes, and benzoheterocycles, which should expand the chemical space of precursors to fine chemicals and polymers. Importantly, a sustainable solvent, dimethyl isosorbide, is used, making this protocol more attractive from the point of view of green chemistry.
- Huang, Xia,Jin, Jian,Lei, Chuanhu,Su, Mincong
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supporting information
(2022/01/15)
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- DIBALH: From known fundamental to an unusual reaction; Chemoselective partial reduction of tertiary amides in the presence of esters
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This study presents a quick and reliable approach to the chemoselective partial reduction of tertiary amides to aldehydes in the presence of readily reducible ester groups using commercial DIBALH reagent. Moreover, the developed method was also extended to multi-functional molecules bearing ester moieties, which were successfully chemoselectively reduced to the corresponding aldehydes. This journal is
- An, Duk Keun,Heo, Yu Jin,Jaladi, Ashok Kumar,Kim, Hyun Tae
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p. 33809 - 33813
(2021/12/09)
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- Vinyl Thianthrenium Tetrafluoroborate: A Practical and Versatile Vinylating Reagent Made from Ethylene
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The use of vinyl electrophiles in synthesis has been hampered by the lack of access to a suitable reagent that is practical and of appropriate reactivity. In this work we introduce a vinyl thianthrenium salt as an effective vinylating reagent. The bench-stable, crystalline reagent can be readily prepared from ethylene gas at atmospheric pressure in one step and is broadly useful in the annulation chemistry of (hetero)cycles, N-vinylation of heterocyclic compounds, and palladium-catalyzed cross-coupling reactions. The structural features of the thianthrene core enable a distinct synthesis and reactivity profile, unprecedented for other vinyl sulfonium derivatives.
- Juliá, Fabio,Paulus, Fritz,Ritter, Tobias,Yan, Jiyao
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supporting information
p. 12992 - 12998
(2021/09/03)
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- The Stereoselective Oxidation of para-Substituted Benzenes by a Cytochrome P450 Biocatalyst
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The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced were oxidised with high activity by the S244D mutant (product formation rates >60 nmol.(nmol-CYP)?1.min?1) and with total turnover numbers of up to 20,000. Ethyl α-hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S-oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98 %). The crystal structure of 4-methoxybenzoic acid-bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereoselective hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme.
- Chao, Rebecca R.,Lau, Ian C.-K.,Coleman, Tom,Churchman, Luke R.,Child, Stella A.,Lee, Joel H. Z.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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supporting information
p. 14765 - 14777
(2021/09/14)
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- Nickel-Catalyzed Ligand-Free Hiyama Coupling of Aryl Bromides and Vinyltrimethoxysilane
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We herein disclose the first Ni-catalyzed Hiyama coupling of aryl halides with vinylsilanes. This protocol uses cheap, nontoxic, and stable vinyltrimethoxysilane as the vinyl donor, proceeds under mild and ligand-free conditions, furnishing a diverse variety of styrene derivatives in high yields with excellent functional group compatibility.
- Wei, Shichao,Mao, Yongjun,Shi, Shi-Liang
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supporting information
p. 1670 - 1674
(2021/02/26)
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- Liquid-phase oxidation of olefins with rare hydronium ion salt of dinuclear dioxido-vanadium(V) complexes and comparative catalytic studies with analogous copper complexes
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Homogeneous liquid-phase oxidation of a number of aromatic and aliphatic olefins was examined using dinuclear anionic vanadium dioxido complexes [(VO2)2(salLH)]? (1) and [(VO2)2(NsalLH)]? (2) and dinuclear copper complexes [(CuCl)2(salLH)]? (3) and [(CuCl)2(NsalLH)]? (4) (reaction of carbohydrazide with salicylaldehyde and 4-diethylamino salicylaldehyde afforded Schiff-base ligands [salLH4] and [NsalLH4], respectively). Anionic vanadium and copper complexes 1, 2, 3, and 4 were isolated in the form of their hydronium ion salt, which is rare. The molecular structure of the hydronium ion salt of anionic dinuclear vanadium dioxido complex [(VO2)2(salLH)]? (1) was established through single-crystal X-ray analysis. The chemical and structural properties were studied using Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis), 1H and 13C nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). In the presence of hydrogen peroxide, both dinuclear vanadium dioxido complexes were applied for the oxidation of a series of aromatic and aliphatic alkenes. High catalytic activity and efficiency were achieved using catalysts 1 and 2 in the oxidation of olefins. Alkenes with electron-donating groups make the oxidation processes easy. Thus, in general, aromatic olefins show better substrate conversion in comparison to the aliphatic olefins. Under optimized reaction conditions, both copper catalysts 3 and 4 fail to compete with the activity shown by their vanadium counterparts. Irrespective of olefins, metal (vanadium or copper) complexes of the ligand [salLH4] (I) show better substrate conversion(%) compared with the metal complexes of the ligand [NsalLH4] (II).
- Maurya, Abhishek,Haldar, Chanchal
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- Organophotoredox-Mediated Amide Synthesis by Coupling Alcohol and Amine through Aerobic Oxidation of Alcohol
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The combination of an organic photocatalyst [4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6 dicyanobenzene) or 5MeOCzBN (2,3,4,5,6-pentakis(3,6-dimethoxy-9 H-carbazol-9-yl)benzonitrile)], quinuclidine, and tetra-n-butylammonium phosphate (hydrogen-bonding catalyst) was employed for amide bond formations. The hydrogen-bonded OH group activated the adjacent C?H bond of alcohols towards hydrogen atom transfer (HAT) by a radical species. The quinuclidinium radical cation, generated through single-electron oxidation of quinuclidine by the photocatalyst, employed to abstract a hydrogen atom from the α-C?H bond of alcohols selectively due to a polarity effect-produced α-hydroxyalkyl radical, which subsequently converted to the corresponding aldehyde under aerobic conditions. Then the coupling of the aldehyde and an amine formed a hemiaminal intermediate that upon photocatalytic oxidation produced the amide.
- Samanta, Samya,Shah, Sk. Sheriff,Shee, Maniklal,Singh, Amit Kumar,Singh, N. D. Pradeep,Venkatesh, Yarra
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supporting information
(2020/03/05)
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- Creation of Redox-Active PdSx Nanoparticles Inside the Defect Pores of MOF UiO-66 with Unique Semihydrogenation Catalytic Properties
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Semihydrogenation of alkynes to produce alkenes is very important in the industry; however, over-hydrogenation heavily complicates the postprocesses, which are highly energy consuming and not environmentally friendly. One of the most efficient pathways to solve this challenging issue is to develop highly selective catalysts that could only hydrogenate alkynes and are inactive in hydrogenation of alkenes. This work presents herein an efficient catalyst, consisting of in situ created PdS0.53 nanoparticles as the redox-active sites inside the defect pores of metal–organic framework UiO-66, which demonstrates very high alkene selectivity (up to 99.5%) in semihydrogenation of easily over-hydrogenated terminal alkynes. In contrast to the traditional catalysts, strict control over the reaction time becomes the nonessential condition because the catalyst system is almost inactive in hydrogenation of alkenes. Therefore, this paradigm work provides a practically applicable pathway for the development of efficient catalysts with unique catalytic properties for selective semihydrogenation reactions.
- Dong, Ming-Jie,Wang, Xuan,Wu, Chuan-De
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- Overcoming Selectivity Issues in Reversible Catalysis: A Transfer Hydrocyanation Exhibiting High Kinetic Control
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Reversible catalytic reactions operate under thermodynamic control, and thus, establishing a selective catalytic system poses a considerable challenge. Herein, we report a reversible transfer hydrocyanation protocol that exhibits high selectivity for the thermodynamically less favorable branched isomer. Selectivity is achieved by exploiting the lower barrier for C-CN oxidative addition and reductive elimination at benzylic positions in the absence of a cocatalytic Lewis acid. Through the design of a novel type of HCN donor, a practical, branched-selective, HCN-free transfer hydrocyanation was realized. The synthetically useful resolution of a mixture of branched and linear nitrile isomers was also demonstrated to underline the value of reversible and selective transfer reactions. In a broader context, this work demonstrates that high kinetic selectivity can be achieved in reversible transfer reactions, thus opening new horizons for their synthetic applications.
- Bhawal, Benjamin N.,Ehinger, Christian,Morandi, Bill,Reisenbauer, Julia C.
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supporting information
p. 10914 - 10920
(2020/07/13)
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- Copper-Catalyzed Defluorinative Hydroarylation of Alkenes with Polyfluoroarenes
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A catalytic defluorinative hydroarylation of alkenes with polyfluoroarenes in the presence of dppbz-ligated Cu catalyst and silanes was developed. This method provides a straightforward and alternative avenue to synthetic important polyfluorinated arenes with readily available and bench-stable alkenes as latent nucleophiles, and therefore avoids conventional reliance on stoichiometric quantities of organometallic reagents. This reaction proceeds under very mild conditions and exhibits good functional group compatibility and high level of regioselectivity. The synthetic potential of this method was further demonstrated by a gram-scale synthesis, and an array of experimental studies were also carried out to elaborate the probable mechanism.
- Fu, Bin,Li, Xiaohong,Xiong, Tao,Yuan, Xiuping,Zhang, Qian,Zhang, Qiao
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supporting information
p. 23056 - 23060
(2020/10/19)
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- Mechanistic Study of Palladium-Catalyzed Hydroesterificative Copolymerization of Vinyl Benzyl Alcohol and CO
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The copolymerization of vinyl benzyl alcohol (VBA) and carbon monoxide (CO) to give a new polyester poly(VBA-CO) has been achieved via palladium-catalyzed hydroesterification. Reaction conditions involve moderate temperatures, moderate to low CO pressures, and low catalyst loadings to give a low molar mass (Mn 3-4 kg/mol) polymer as a 2:1 mixture of linear to branched repeat units. The polymer molar mass increase is consistent with a step-growth polymerization mechanism, and ester yields of >97% are achieved within 24 h. However, increases in Mn cease beyond 16 h. Control experiments indicate that the degree of polymerization is limited due to a combination of side reactions such as alcoholic end-group oxidation, hydroxycarbonylation, and alcohol acetylation, which lead to the degradation of monomeric and polymeric end groups. When a less promiscuous substrate is used such as 10-undecenol, higher molar masses (Mn 16 kg/mol) are achieved. This method has the potential to be a mild route to new polyester architectures with appropriate mitigation of side reactions.
- Yee, Gereon M.,Wang, Tong,Hillmyer, Marc A.,Tonks, Ian A.
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p. 1778 - 1786
(2019/04/30)
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- Pd-Catalyzed Vinylation of Aryl Halides with Inexpensive Organosilicon Reagents Under Mild Conditions
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Pd-catalyzed Hiyama vinylation reaction of non-activated aryl chlorides and bromides under mild conditions was developed. The use of efficient vinyl donors and electron-rich sterically hindered phosphine ligands was critical for the success of the reaction. The products of this transformation can be used for Am/Cm separation, an important challenge in nuclear fuel reprocessing. The substituent effect on Am/Cm separating selectivity was also achieved, which could contribute to the development of new chromatographic materials for the separation of Am and Cm.
- Yang, Chu-Ting,Han, Jun,Liu, Jun,Li, Yi,Zhang, Fan,Yu, Hai-Zhu,Hu, Sheng,Wang, Xiaolin
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supporting information
p. 10324 - 10328
(2018/07/31)
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- Additive-modulated switchable reaction pathway in the addition of alkynes with organosilanes catalyzed by supported Pd nanoparticles: Hydrosilylation: versus semihydrogenation
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We herein report supported Pd nanoparticles on N,O-doped hierarchical porous carbon as a single operation catalyst-enabled additive-modulated reaction pathway for alkynes addition with organosilanes between hydrosilyation and semihydrogenation. In the case of alkynes hydrosilylation, a simple iodide ion as an additive has a promotion effect on the activity and regio- and stereoselectivity, where iodide can coordinate with Pd NPs via strong δ donation to increase the electron density of the Pd atom, resulting in an increased ability for the oxidative addition of hydrosilane as the rate-determining step to make the reaction proceed efficiently to afford vinylsilanes in high yields with excellent regio- and stereoselectivity. For the catalytic transfer semihydrogenation of alkynes, water was introduced to mix with organosilane to form a silanol together with the generation of hydrogen atoms on the Pd NPs surface or the liberation of H2 gas as a reducing agent, whereby the quantitative reduction of alkynes was achieved with exclusive selectivity to alkenes. In both cases, the catalyst could be recycled several times without a significant loss in activity or selectivity. A broad range of alkyl and aryl alkynes with various functional groups are compatible with the reaction conditions. The role the additive exerted in each reaction was extensively investigated through control experiments as well as the kinetic isotopic effect along with spectroscopic characterization. In addition, the respective mechanism operating in both reactions was proposed.
- Duan, Yanan,Ji, Guijie,Zhang, Shaochun,Chen, Xiufang,Yang, Yong
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p. 1039 - 1050
(2018/03/05)
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- Synthesis of Aldehydes by Organocatalytic Formylation Reactions of Boronic Acids with Glyoxylic Acid
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Reported herein is a conceptually novel organocatalytic strategy for the formylation of boronic acids. New reactivity is engineered into the α-amino-acid-forming Petasis reaction occurring between aryl boronic acids, amines, and glyoxylic acids to prepare aldehydes. The operational simplicity of the process and its ability to generate structurally diverse and valued aryl, heteroaryl, and α,β-unsaturated aldehydes containing a wide array of functional groups, demonstrates the practical utility of the new synthetic strategy.
- Huang, He,Yu, Chenguang,Li, Xiangmin,Zhang, Yongqiang,Zhang, Yueteng,Chen, Xiaobei,Mariano, Patrick S.,Xie, Hexin,Wang, Wei
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supporting information
p. 8201 - 8205
(2017/06/30)
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- Palladium Nanoparticle Loaded Bifunctional Silica Hybrid Material: Preparation and Applications as Catalyst in Hydrogenation Reactions
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Bifunctional mesoporous silica was prepared by co-condensation of tetraethyl orthosilicate (TEOS) with functionalized organosilanes containing azides or alkoxyamines. Orthogonal functional groups at the particles were selectively addressed in subsequent chemical modifications through “click”-chemistry (“click to ligand” strategy) and radical nitroxide exchange. Palladation with PdCl2 delivered Pd nanoparticle-loaded silica material bearing sulfoxides and additional aminoamides as stabilizing ligands by means of in situ reduction of the PdII-salt. These functional particles were successfully applied to the hydrogenation of alkynes and alkenes. Aldehyde hydrodeoxygenation and benzyl ether cleavage were achieved with these hybrid catalysts under mild conditions. Particles were analyzed by IR, TEM/STEM, EDX, and solid-state NMR spectroscopy.
- Surmiak, Sabrina K.,Doerenkamp, Carsten,Selter, Philipp,Peterlechner, Martin,Sch?fer, Andreas H.,Eckert, Hellmut,Studer, Armido
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p. 6019 - 6028
(2017/05/05)
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- Synthesis of Supported Planar Iron Oxide Nanoparticles and Their Chemo- and Stereoselectivity for Hydrogenation of Alkynes
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Nature uses enzymes to dissociate and transfer H2 by combining Fe2+ and H+ acceptor/donor catalytic active sites. Following a biomimetic approach, it is reported here that very small planar Fe2,3+ oxide nanoparticles (2.0 ± 0.5 nm) supported on slightly acidic inorganic oxides (nanocrystalline TiO2, ZrO2, ZnO) act as bifunctional catalysts to dissociate and transfer H2 to alkynes chemo- and stereoselectively. This catalyst is synthesized by oxidative dispersion of Fe0 nanoparticles at the isoelectronic point of the support. The resulting Fe2+,3+ solid catalyzes not only, in batch, the semihydrogenation of different alkynes with good yields but also the removal of acetylene from ethylene streams with >99.9% conversion and selectivity. These efficient and robust non-noble-metal catalysts, alternative to existing industrial technologies based on Pd, constitute a step forward toward the design of fully sustainable and nontoxic selective hydrogenation solid catalysts.
- Tejeda-Serrano, María,Cabrero-Antonino, Jose R.,Mainar-Ruiz, Virginia,López-Haro, Miguel,Hernández-Garrido, Juan C.,Calvino, José J.,Leyva-Pérez, Antonio,Corma, Avelino
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p. 3721 - 3729
(2017/06/09)
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- Mechanism of the Novel Prenylated Flavin-Containing Enzyme Ferulic Acid Decarboxylase Probed by Isotope Effects and Linear Free-Energy Relationships
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Ferulic acid decarboxylase from Saccharomyces cerevisiae catalyzes the decarboxylation of phenylacrylic acid to form styrene using a newly described prenylated flavin mononucleotide cofactor. A mechanism has been proposed, involving an unprecedented 1,3-dipolar cyclo-addition of the prenylated flavin with the α=β bond of the substrate that serves to activate the substrate toward decarboxylation. We measured a combination of secondary deuterium kinetic isotope effects (KIEs) at the α- and β-positions of phenylacrylic acid together with solvent deuterium KIEs. The solvent KIE is 3.3 on Vmax/KM but is close to unity on Vmax, indicating that proton transfer to the product occurs before the rate-determining step. The secondary KIEs are normal at both the α- and β-positions but vary in magnitude depending on whether the reaction is performed in H2O or D2O. In D2O, the enzyme catalyzed the exchange of deuterium into styrene; this reaction was dependent on the presence of bicarbonate. This observation implies that CO2 release must occur after protonation of the product. Further information was obtained from a linear free-energy analysis of the reaction through the use of a range of para- and meta-substituted phenylacrylic acids. Log(kcat/KM) for the reaction correlated well with the Hammett σ- parameter with p= -0.39 ± 0.03; r2 = 0.93. The negative p value and secondary isotope effects are consistent with the rate-determining step being the formation of styrene from the prenylated flavin-product adduct through a cyclo-elimination reaction.
- Ferguson, Kyle L.,Arunrattanamook, Nattapol,Marsh, E. Neil G.
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p. 2857 - 2863
(2016/07/16)
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- Method of manufacturing calbonyl compd.
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PROBLEM TO BE SOLVED: To provide a method of manufacturing a carbonyl compound by smoothly performing a dehydrogenation reaction while preventing side reactions.SOLUTION: A method of manufacturing a carbonyl compound includes a process of converting alcohol to aldehyde or ketone by irradiating visible light to a reaction system containing a primary alcohol or a secondary alcohol, SrTiOcarrying a Ru atom and doped with Rh atom, and water.
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Paragraph 0051; 0053
(2018/06/30)
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- New styrene derivative and method (by machine translation)
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PROBLEM TO BE SOLVED: represented by chemical eq. (1), a copolymer of vinyl monomers used in the polymerization of styrene compound, and a manufacturing method thereof. SOLUTION: the styrene-based compound, and halogenated alkyl bistriphenylphosphine generates a reaction reagent Wittig, vinyl and the reagent Wittig nitrobenzaldehyde synthesized by reacting. ( In the formula, n is 0 or 1 and, R1 and R2 are, independently, a hydrogen atom, or, bisquaternary carbon number 3 or less, and, R1 and R2 of the total number of carbon atoms in the number of carbon atoms in 3 or more 5 or less. ) Selected drawing: no (by machine translation)
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Paragraph 0028; 0029
(2016/10/07)
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- Fabrication of Ultrafine Palladium Phosphide Nanoparticles as Highly Active Catalyst for Chemoselective Hydrogenation of Alkynes
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Monodisperse palladium phosphide nanoparticles (Pd-P NPs) with a smallest size ever reported of 3.9nm were fabricated using cheap and stable triphenylphosphine as phosphorous source. After the deposition and calcination at 300 °C and 400 °C, the resulting Pd-P NPs increased in size to 4.0nm and 4.8nm, respectively. Notably, the latter NPs probably crystallized with a single phase of Pd3P0.95, which acted as a highly active catalyst in semi-and stereoselective hydrogenation of alkynes. X-ray photoelectron spectroscopy analysis determined a positive shift of binding energy for Pd(3d) in Pd-P NPs compared to that in Pd on carbon. It indicated the electron flow from metal to phosphorus and the larger electron deficiency of Pd in Pd-P NPs, which suppressed palladium hydride formation and subsequently increased the selectivity. Thus, this result may also indicate the applications of Pd-P and other metal-P NPs in various selective hydrogenation reactions.
- Zhao, Ming
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p. 461 - 464
(2016/03/12)
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- Metalated porous porphyrin polymers as efficient heterogeneous catalysts for cycloaddition of epoxides with CO2 under ambient conditions
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We have successfully synthesized a porphyrin based porous organic polymer (POP-TPP) from free-radical polymerization of tetrastyrylporphyrin monomer under solvothermal conditions. Besides high surface area (1200 m2/g) and high thermal stability, the obtained polymer features open metal chelating sites, and thus the catalytic activities of metalloporphyrins can be reasonably adjusted by introducing various metal ions. After metalation with Co3+, Zn2+, and Mg2+, the Co/POP-TPP, Zn/POP-TPP, and Mg/POP-TPP as heterogeneous catalysts are very active for cycloaddition of epoxides with CO2 to cyclic carbonates at ambient conditions with n-Bu4NBr as a nucleophilic additive. Particularly, under the relatively low CO2 concentration (15% in volume), the activity of heterogeneous Co/POP-TPP catalyst is even higher than that of the corresponding homogeneous Co/TPP catalyst. More importantly, there is no activity loss even if the Co/POP-TPP is recycled for 18 times. The excellent catalytic activity and superior recyclability of the obtained catalysts indicate that the porphyrin based porous organic polymer is a promising candidate for construction of efficient heterogeneous catalysts in the future.
- Dai, Zhifeng,Sun, Qi,Liu, Xiaolong,Bian, Chaoqun,Wu, Qinming,Pan, Shuxiang,Wang, Liang,Meng, Xiangju,Deng, Feng,Xiao, Feng-Shou
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p. 202 - 209
(2016/04/05)
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- Iron-catalysed chemo-, regio-, and stereoselective hydrosilylation of alkenes and alkynes using a bench-stable iron(II) pre-catalyst
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The chemo-, regio-, and stereoselective iron-catalysed hydrosilylation of alkenes and alkynes with excellent functional group tolerance is reported (34 examples, 41-96% yield). The catalyst and reagents are commercially available and easy to handle, with the active iron catalyst being generated in situ, thus providing a simple and practical methodology for iron-catalysed hydrosilylation. The silane products can be oxidised to the anti-Markovnikov product of olefin hydration, and the one-pot iron-catalysed hydrosilylation-oxidation of olefins to give silane(di)ols directly is also reported. The iron pre-catalyst was used at loadings as low as 0.07 mol%, and displayed catalyst turnover frequencies (TOF) approaching 60,000 molh-1. Initial mechanistic studies indicate an iron(I) active catalyst.
- Greenhalgh, Mark D.,Frank, Dominik J.,Thomas, Stephen P.
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supporting information
p. 584 - 590
(2014/05/20)
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- Oxidative cleavage of benzylic C-N bonds under metal-free conditions
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An interesting procedure for the oxidative cleavage of benzylic C-N bonds has been developed. Using TBAI as the catalyst and H2O2as the oxidant, various benzylamines were transformed into their corresponding aromatic aldehydes in moderate to good yields. Notably, this is the first example of an oxidative cleavage of benzylic C-N bonds under metal-free conditions.
- Gong, Jin-Long,Qi, Xinxin,Wei, Duo,Feng, Jian-Bo,Wu, Xiao-Feng
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p. 7486 - 7488
(2014/12/11)
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- Cis-specific hydrofluorination of alkenylarenes under palladium catalysis through an ionic pathway
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This paper describes the hydrofluorination of alkenes through sequential H- and F+ addition under palladium catalysis. The reaction is cis specific, thus providing access to benzylic fluorides. The mechanism of this reaction involves an ionic pathway and is distinct from known hydrofluorinations involving radical intermediates. The first catalytic enantioselective hydrofluorination is also disclosed. See attached PdF: A series of benzylic fluorides was prepared by hydrofluorination which proceeds through a PdII/IV catalytic manifold. The method is mechanistically distinct from previously reported radical hydrofluorination, and is characterized by its clean regioselectivity and unique cis stereospecificity. The first example of enantioselective net HF addition onto 2-vinylnaphthalene is also disclosed.
- Emer, Enrico,Pfeifer, Lukas,Brown, John M.,Gouverneur, Veronique
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supporting information
p. 4181 - 4185
(2014/05/06)
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- Ratiometric fluorescent probes for detection of intracellular singlet oxygen
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We have developed a series of molecular probes for the fluorescent detection of singlet dioxygen (1O2). The probes, based on asymmetrically substituted 1,3-diarylisobenzofurans, undergo the [2 + 4] cycloaddition reaction with 1O2, producing ratiometric fluorescent responses. Two-photon fluorescence microscope experiments demonstrated the biological utility of the probes for the visualization of endogenous 1O2 in macrophage cells.
- Song, Dayoung,Cho, Somin,Han, Yejee,You, Youngmin,Nam, Wonwoo
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supporting information
p. 3582 - 3585
(2013/08/23)
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- Redox-selective generation of aldehydes and H2 from alcohols under visible light
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Photosynthetic dehydrogenation: Potential usefulness of visible-light-induced dehydrogenation of alcohols in organic synthesis was demonstrated, in which aldehydes and H2 were afforded by using Ru/SrTiO3:Rh and water (see scheme). Water was essential for the reaction. High efficiency (TON: up to 15 400 based on Rh; H2 and aldehyde evenly generated) and high selectivity were achieved. Copyright
- Liu, Zijun,Caner, Joaquim,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 9452 - 9456
(2013/07/26)
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- Metal-ligand core-shell nanocomposite catalysts for the selective semihydrogenation of alkynes
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Catalysts with a sheltered upbringing: Novel core-shell nanocomposite catalysts consisting of active metal nanoparticles encapsulated by macroligands have been prepared. They have Pd nanoparticles (PdNPs) as an active core and shell ligands having sulfoxide moieties coordinated to the PdNPs. The shell protects the catalyst from coordination by alkenes and allows the lead-free selective semihydrogenation of a wide range of alkynes without any additives (see scheme). Copyright
- Mitsudome, Takato,Takahashi, Yusuke,Ichikawa, Satoshi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 1481 - 1485
(2013/04/10)
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- Organic bulk heterojunction solar cells based on solution processable small molecules (A-π-A) featuring 2-(4-nitrophenyl) acrylonitrile acceptors and phthalimide-based π-linkers
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A novel small molecule-based organic donor SM [(2Z,2′Z)-3,3′- (((1E,1′E)-(2-cyclohexyl-1,3-dioxoisoindoline-4,7-diyl)bis(ethene-2, 1-diyl))bis(4,1-phenylene))bis(2-(4-nitrophenyl)-acrylonitrile)] featuring 2-(4-nitrophenyl)acrylonitrile as the acceptor and a π-conjugation bridge composed of phthalimide and styryl units, with an A-π-A type structure, has been synthesized. It showed a long wavelength absorption band having an absorption maximum around 635 nm and the optical bandgap was 1.63 eV, which is lower than most reported conjugated polymers, including poly(3-hexylthiophene) (P3HT). The photovoltaic properties were investigated by constructing bulk heterojunction organic solar cell devices using SM as the electron donor and fullerene derivatives, i.e. PC60BM and PC70BM as the electron acceptors with the device architecture ITO/PEDOT:PSS/SM:PC 60BM or PC70BM/Al. The effect of the SM/fullerene derivative weight ratio and the processing solvent were carefully investigated to improve the performance of the organic solar cells. The optimized organic solar cell with SM:PC60BM and SM:PC70BM cast from THF solvent, at a weight ratio of 1:3 showed power conversion efficiencies (PCEs) of about 1.70% and 2.56%, respectively. The enhanced value of PCE for the BHJ photovoltaic device based on PC70BM is related to the better absorption of PC70BM in the visible region compared to that of PC60BM. The SM:PC70BM blends cast from a DIO-THF mixture and subsequent thermal annealing exhibited improved PCEs of 3.68% and 4.14%, respectively.
- Sharma,Mikroyannidis,Kurchania, Rajnish,Thomas, K. R. Justin
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body text
p. 13986 - 13995
(2012/08/08)
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- An easy access to styrenes: Trans aryl 1,3-, 1,4- and 1,5-dienes, and 1,3,5-trienes by Hiyama cross-coupling catalyzed by palladium nanoparticles
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A convenient and efficient procedure has been developed for the vinylation of aryl-, styrenyl-, cinnamyl- and dienyl-halides by a Pd(0) nanoparticle-catalyzed Hiyama cross-coupling to provide the corresponding dienes and trienes in high yields. The reaction does not require any ligand or co-catalyst, and is carried out using PdCl2 and tetrabutyl ammonium fluoride (TBAF) in THF. Pd nanoparticles are generated in situ and are the active catalytic species in this reaction. A wide range of functionalized styrenes, trans aryl 1,3-, 1,4- and 1,5- dienes, 1,2-, 1-3 and 1,4-bis(1,3-dienes), and 1,3,5-trienes can be obtained by this procedure. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
- Chatterjee, Tanmay,Dey, Raju,Ranu, Brindaban C.
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experimental part
p. 1103 - 1110
(2011/07/08)
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- Wittig like methylenation of aldehydes in a microflow system: Selective methylenation by differential of plural reactions
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Methylenation of aldehydes with bis(iodozincio)methane was performed using a microflow system. Treatment of a dialdehyde with bis(iodozincio)methane in the system can divide two methylenation reactions and realize selective transformation.
- Takada, Yoshiaki,Matsubara, Seijiro
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scheme or table
p. 364 - 365
(2011/05/04)
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- Low pressure vinylation of aryl and vinyl halides via Heck-Mizoroki reactions using ethylene
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Aryl bromides and iodides in the presence of catalytic amounts of a palladacycle derived from acetophenone oxime and 2 equiv of potassium acetate react with ethylene under ambient pressure (15-30 psi) to give the corresponding vinylarenes. The reactions work with both electron-deficient and electron-rich aryl compounds and tolerate wide variety of common functional groups. Vinyl bromides lead to 1,3-dienes in moderate yields.
- Smith, Craig R.,RajanBabu
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supporting information; experimental part
p. 1102 - 1110
(2010/03/25)
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- The formation of core cross-linked star polymers containing cores cross-linked by dynamic covalent imine bonds
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Diblock copolymers possessing amino or aldehyde functions within one of their blocks were prepared using RAFT polymerization techniques. These polymers were shown to cross-link through dynamic imine bonds to form core cross-linked star polymers which display a size-dependency upon the concentration at which the cross-linking reactions are performed.
- Jackson, Alexander W.,Fulton, David A.
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supporting information; experimental part
p. 6051 - 6053
(2010/11/02)
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- Pairing fullerenes and porphyrins: Supramolecular wires that exhibit charge transfer activity
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A concept is elaborated of pairing electron donors and electron acceptors that share a common trait, wire-like features, as a powerful means to realize a new and versatile class of electron donor-acceptor nanohybrids. Important variables are fine-tuning (i) the complexation strength, (ii) the electron/energy transfer behavior, and (iii) the solubilities of the resulting architectures. In particular, a series of supramolecular porphyrin/fullerene hybrids assembled by the hydrogen bonding of Hamilton receptor/cyanuric acid motif has been realized. Putting the aforementioned variables into action, the association constants (Kass), as they were determined from 1H NMR and steady-state fluorescence assays, were successfully tweaked with values in the range of 104-105 M -1. In fact, our detailed studies corroborate that the latter reveal a dependence on the nature of the spacer, that is, p-phenylene-ethynylene, p-phenylene-vinylene, p-ethynylene, and fluorene, as well as on the length of the spacer. Complementary performed transient absorption studies confirm that electron transfer is indeed the modus operandi in our novel class of electron donor-acceptor nanohybrids, while energy transfer plays, if any, only a minor role. The accordingly formed electron transfer products, that is, one-electron oxidized porphyrins and one-electron reduced fullerenes, are long-lived with lifetimes that reach well into the time domain of tens of nanoseconds. Finally, we have used the distance dependence on electron transfer, charge separation and charge recombination, to determine for the first time a ss value (0.11-1) for hydrogen-bonding-mediated electron transfer.
- Wessendorf, Florian,Grimm, Bruno,Guldi, Dirk M.,Hirsch, Andreas
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supporting information; experimental part
p. 10786 - 10795
(2010/09/17)
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- FLUOROPHORE AND FLUORESCENT SENSOR COMPOUND CONTAINING SAME
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The invention provides fluorophores of formulae (I) and (II) and also fluorescent sensor compounds comprising fluorophore moieties based on such fluorophores in combination with a receptor moiety. There is further provided a method of sensing the presence of a target analyte using the fluorescent sensor compound, as well as the use of the fluorescent sensor compounds to sense a target analyte.
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Page/Page column 58-60
(2010/11/03)
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- Carbonylation of aryl halides: Extending the scope of the reaction
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Carbonylation reactions are being increasingly favoured in pharmaceutical chemistry for the atom-efficient introduction of carbonyl centres in aldehydes, acids, esters, and amides. Convenient procedures for simple aryl iodides and bromides are well established, and now the need is to develop improved conditions to allow the reactions to be extended to the more unreactive substrates, such as sterically hindered compounds and aryl chlorides. Sterically hindered compounds such as 2-iodo- or 2-bromo-m-xylenes can be converted using alkoxy and aminocarbonylation, while dehalogenation becomes a significant side reaction for reductive carbonylation. Less hindered compounds such as 2-iodo- or bromotoluene can be reacted successfully. Changing the aryl ligands of PdCl2{Ph2P(CH2)3PPh2} to alkyl groups improves the rate of oxidative addition but slows the carbonyl insertion step such that rates for the majority of aryl bromides are not improved by this change. Complexes such as PdCl2{Cy 2P(CH2)3PCy2} offer better performance for alkoxy and aminocarbonylation of aryl chlorides. However, for reductive carbonylation dehalogenation is a significant side reaction. Increasing CO pressure results in additional CO coordination to the catalytic intermediates and slows the reaction, while the dehalogenation is little affected, so reaction selectivity suffers. Thus, CO pressure is a critical parameter, particularly for reductive carbonylation, in achieving the optimum performance.
- Barnard, Christopher F.J.
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p. 566 - 574
(2013/01/03)
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- Direct vinylation and difluorovinylation of arylboronic acids using vinyl- and 2,2-difluorovinyl tosylates via the Suzuki-Miyaura cross coupling
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(Chemical Equation Presented) General reaction conditions were developed for the Pd(0)-catalyzed Suzuki-Miyaura coupling reaction of aryl boronic acids with a simple electrophilic vinylation reagent, vinyl tosylate, providing access to styrene derivatives in good yields. The easily accessible vinyl tosylate represents a stable and less toxic alternative to the vinyl halides and the triflate/nonaflate derivatives. Furthermore, this methodology was expanded to provide a facile and straightforward approach for the introduction of a gem-difluorovinyl substituent onto an aromatic ring using the similar and also readily available 2,2-difluorovinyl tosylate as the electrophilic complement.
- Gogsig, Thomas M.,Sobjerg, Lina S.,Lindhardt, Anders T.,Jensen, Kim L.,Skrydstrup, Troels
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p. 3404 - 3410
(2008/09/21)
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- Evaluation of polymer-supported vinyltin reagents in the Stille cross-coupling reaction
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The synthesis of two new vinyltin reagents grafted on an insoluble macroporous polymer is reported. These reagents were used in the palladium-catalyzed Stille cross-coupling reaction with aryl halides. In all reactions, the conversion of the starting aryl halide is high and the amount of organotin by-product is particularly low (at the end of the catalytic run, the amount of Sn is up to 16 ppm in the crude reaction mixture removed of the insoluble polymer, and it is less than 1 ppm in the product purified by chromatography on silica gel).
- Chrétien, Jean-Mathieu,Mallinger, Aurélie,Zammattio, Fran?oise,Grognec, Erwan Le,Paris, Micha?l,Montavon, Gilles,Quintard, Jean-Paul
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p. 1781 - 1785
(2008/02/05)
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- Intermolecular reactions of chlorohydrine anions: Acetalization of carbonyl compounds under basic conditions
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Nonenolizable aldehydes and ketones react with 2-chloroethanol and 3-chloropropanol under basic conditions (t-BuOK, DMF/THF) with formation of 2-substituted 1,3-dioxolanes and 1,3-dioxanes, respectively. Conversion of the two-step addition-alkylation process depends on the electrophilicity of the carbonyl group that governs the equilibrium of addition of chloroalkoxides. This method of protection of carbonyl groups in the form of cyclic acetals under kinetically controlled conditions is complementary to the acid-catalyzed reaction with diols.
- Barbasiewicz, Michal,Makosza, Mieczyslaw
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p. 3745 - 3748
(2007/10/03)
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- Single-molecule charge-transport measurements that reveal technique-dependent perturbations
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We compare scanning tunneling microscopy (STM) imaging with single-molecule conductive atomic force microscopy (C-AFM) measurements by probing a series of structurally related thiol-terminated oligo(phenylenevinylene)s (OPVs) designed to have unique charge-transport signatures. When one or two methylene spacers are inserted between the thiol points of attachment and the OPV core, a systematic reduction in the imaged molecular transconductance and the current transmitted through a metal-molecule-metal junction containing the molecule is observed, indicating good agreement between STM and C-AFM measurements. However, a structure where the OPV backbone is interrupted by a [2.2]paracyclophane core has a low molecular transconductance, as determined from STM images, and a high measured single-molecule conductance. This apparent disconnect can be understood by comparing the calculated molecular orbital topology of the OPV with one thiol bound to a gold surface (the geometry in the STM experiment) with the topology of the molecule with both thiol termini bound to gold (relevant to C-AFM). In the former case, a single contact splits low-lying molecular orbitals into two discrete fragments, and in the latter case, molecular orbitals that span the entire molecule are observed. Although the difference in observed conductance between the two different measurements is resolved, the overall set of observations highlights the importance of using combined techniques to better characterize charge-transport properties relevant to molecular electronics.
- Seferos, Dwight S.,Blum, Amy Szuchmacher,Kushmerick, James G.,Bazan, Guillermo C.
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p. 11260 - 11267
(2007/10/03)
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- Suzuki-Miyaura cross-coupling reactions of potassium vinyltrifluoroborate with aryl and heteroaryl electrophiles
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We have previously reported that the palladium-catalyzed cross-coupling reaction of potassium vinyltrifluoroborate with aryl electrophiles proceeds with good yields. Herein, we describe recent progress in optimizing the reaction, as well as outlining the scope and limitations of the reaction. The cross-coupling reaction can generally be effected using 2 mol % of PdCl2 and 6 mol % of PPh3 as a catalyst system in THF/H2O with Cs 2CO3 as a base. Moderate to good yields are obtained in the presence of a variety of functional groups.
- Molander, Gary A.,Brown, Adam R.
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p. 9681 - 9686
(2007/10/03)
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- Preparative fluorous mixture synthesis of diazonium-functionalized oligo(phenylene vinylene)s
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(Chemical Equation Presented) A series of building blocks for the synthesis of oligo(phenylene vinylene)s (OPVs) and hybrid oligomers were prepared, and alternating Heck coupling and Horner-Wadswoth-Emmons (HWE) reactions were used to couple the building blocks. Model studies were carried out to optimize the reaction strategies. The products were made to bear aryl diazonium functionalities that allow them to be used as surface grafting moieties in hybrid silicon/molecule assemblies. A library of OPV and hybrid oligomer tetramers was synthesized using fluorous mixture synthesis (FMS). The fluorous tags, which are secondary amines bearing different numbers of fluorine atoms, were synthesized and used as phase tags in mixture synthesis. The tags and substrates were anchored together by triazene linkages. The mixture synthesis was monitored by analytical HPLC on a fluorous column, and isolation of final OPV and hybrid oligomer tetramers was achieved by preparative HPLC. At the end of the FMS, after demixing, the tagged products were detagged by cleaving the triazene linkage and generating a series of aryl diazonium compounds. The fluorous tags could be recovered and reused. The NMR spectra of the 1-aryl-3,3-dialkyltriazenes are discussed.
- Jian, Huahua,Tour, James M.
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p. 3396 - 3424
(2007/10/03)
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- Toward environmentally friendly photolithographic materials: A new class of water-soluble photoresists
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New water-soluble styrenic polymers bearing two functional groups, pendant ammonium salts of half-esters of malonic acids and acid-labile alkyl esters, were synthesized and evaluated for water-soluble positive-tone photoresist application. These polymers feature two solubility switches: insolubilization of the entire film by baking and selective solubilization upon exposure to UV light. Time-resolved FT-IR measurement of the baked films showed sequential evaporation of ammonia from the films and the decarboxylation of the malonate half-esters. The rates of decarboxylation depend on the structure of substituents at the 2-position of the malonates. The choice of acid-labile esters, the structure of the half-esters, and the polymer compositions were carefully optimized, and high-resolution positive tone images were obtained that were fully processed in aqueous media.
- Yamada, Shintaro,Mrozek, Thomas,Rager, Timo,Owens, Jordan,Rangel, Jose,Willson, C. Grant,Byers, Jeffery
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p. 377 - 384
(2007/10/03)
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- Suzuki cross-coupling reactions between alkenylboronic acids and aryl bromides catalysed by a tetraphosphane-palladium catalyst
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A range of alkenylboronic acids undergo Suzuki cross-coupling with aryl bromides in good yields in the presence of [PdCl(C3H 5)]2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphanyl) methyl]cyclopentane as a catalyst. A wide variety of 1-arylprop-1-enes, 2-arylprop-1-enes, 2-arylbut-1-enes and 1,1-diarylethylene or styrene derivatives have been prepared. Moreover, the reaction tolerates several functions, such as acetyl, formyl, nitrile or nitro. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Peyroux, Eugenie,Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 1075 - 1082
(2007/10/03)
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- Polymeric nitrons. 2. Synthesis, irradiation and waveguide mode spectroscopy of polymeric nitrons derived from polymeric benzaldehydes and N-isopropylhydroxylamine
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Various vinylbenzaldehydes were prepared using the Heck reaction: 4-vinylbenzaldehyde (14), 3-vinylbenzaldehyde (15), 2-vinylbenzaldehyde (18a), 2-hydroxy-4-vinylbenzaldehyde (16) and 4-[(4-vinylbenzyl)oxy]benzaldehyde (6). The four monomers (6, 14, 15, 16) were polymerized using AIBN as initiator at 70 °C for 24 h to yield the corresponding homopolymers (7, 19, 23, 25) and a copolymer (20) with styrene. The molecular weights are about 10 000. The polymer analogous condensation of the aldehyde groups with an excess of N-isopropylhydroxylamine (8) at room temperature produces polymeric nitrons (9, 21, 22, 24, 26) in almost quantitative yields. All nitron functions were irradiated, and the intramolecular cyclization of the nitrons to the corresponding oxaziridines was examined. Waveguide mode spectroscopy of poly(4-vinylbenzaldehyde-N-isopropylnitron) (21) shows that the changes in film thickness are low but the changes in refractive indices are significant after irradiation. Oxaziridine 10 has high thermal stability with respect to ring opening. No structural change was detected after irradiation of the hydrexyphenyl-modified polynitron (26). A low molecular weight model compound (2-hydroxybenzaldehyde-N-methylnitron, 28) was prepared id order to examine this abnormal photochemical behavior and also showed that it is highly resistant to UV irradiation.
- Heinenberg, Michael,Menges, Bernhard,Mittler, Silvia,Ritter, Helmut
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p. 3448 - 3455
(2007/10/03)
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- Improved synthesis of (4-ethenylphenyl)diphenyl methanol and its application in the preparation of trityl functionalized polystyrene resin containing tetrahydrofuran derived cross-linker
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An improved and straightforward synthesis of (4-ethenylphenyl)diphenyl methanol is described. This monomer was used in the preparation of trityl functionalized polystyrene containing a flexible tetrahydrofuran cross-linker, giving rise to a suitable support for solid-phase organic synthesis. (C) 2000 Elsevier Science Ltd.
- Manzotti,Reger,Janda
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p. 8417 - 8420
(2007/10/03)
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