- Application of chemical shifts in 1H and 13C NMR spectra to configuration assignment of Schiff bases in the liquid phase
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In 1H and 13C NMR spectra of N-substituted dimethylketimines chemical shifts of protons and carbon atoms of the methyl groups in the cis-position with respect to the unshared electron pair of the nitrogen are larger than those of the CH3 groups in the trans-position by 0.2-0.4 and 8-11 ppm respectively. This effect is accompanied by the reduction of the corresponding direct spin-spin coupling constant 13C-13C by 10 Hz. The experimental trends in the variation of the spectral parameters are well reproduced by ab initio quantum-chemical calculations. The discovered stereochemical dependence of the chemical shifts of 1H and 13C may underlie a simple and efficient method of the configuration assignment in various compounds with a C=N bond.
- Afonin,Pavlov,Ushakov,Levanova,Levkovskaya
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Read Online
- Uncatalysed Domino Reaction in Hexafluoroisopropanol: A Simple Protocol for the Synthesis of Tetrahydroquinoline Derivatives
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A range of tetrahydroquinolines were synthesised in excellent yields through a domino reaction performed in hexafluoropropanol, starting from anilines and enol ethers and in the absence of Lewis acid catalysis. This solvent was shown to promote the nucleophilic addition of anilines to enol ethers as well as the aza-Diels-Alder reaction.
- Di Salvo, Andrea,Spanedda, Maria Vittoria,Ourevitch, Michele,Crousse, Benoit,Bonnet-Delpon, Daniele
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- The preparation and photocatalytic activity of Ag-Pd/g-C3N4 for the coupling reaction between benzyl alcohol and aniline
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In this study, the carrier g-C3N4 was prepared by melamine, and the Ag-Pd/g-C3N4 catalyst was synthesized by the NaBH4 reduction method. Different characterization techniques, including SEM, TEM, XRD, UV–vis DRS, XPS, photoluminescence spectra (PL) and BET, were employed to investigate the morphology and optical properties of the as-prepared samples. The Ag-Pd/g-C3N4 catalyst was used for the synthesis of imine from a benzyl alcohol and aniline. The results show that when the total loading of Ag and Pd is 2 wt%, and the mass ratio of Ag and Pd is 1:1, the activity of the catalyst is the highest (The highest conversion of aniline is 86.7% and the product selectivity is >99%.). The reaction is optimized by changing the type of solvent, the type and amount of base, the type of catalyst, and the amount of reactants. The optimal reaction conditions are 6 ml of n-hexane, 1.4 mmol of Cs2CO3, 50 mg of the Ag-Pd/g-C3N4 (2 wt%, 1:1), and 2:1 mol ratio of benzyl alcohol and aniline. Under optimal reaction conditions, alcohol derivatives and amine derivatives were investigated to determine the suitable range of the catalyst for alcohols and amines. Then, the effects of different light intensities and wavelengths on the reaction were explored. Additionally, the catalyst's recycling ability was tested, and it was found to be relatively stable. The effect of reactive groups on the mechanism shows that the reaction is mainly achieved by the synergy between h+, e? and ·O2?.
- Ma, Jingjing,Yu, Xiujuan,Liu, Xiaoling,Li, Haiying,Hao,Li, Jingyi
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- Carbon dioxide-promoted selective reductive amination of aliphatic ketones with aniline and hydrogen using a Pt/C catalyst
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Product selectivity in the reductive amination of aliphatic ketones with aniline and H2 using a 5% Pt/C catalyst was improved remarkably in the presence of CO2. The CO formed in situ by the reverse watergas shift reaction selectively poisoned the Pt sites active for undesired side reactions.
- Ichikawa, Shinichiro,Seki, Tsunetake,Ikariya, Takao
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- Ultrasound-assisted construction of a Z-scheme heterojunction with g-C3N4 nanosheets and flower-like Bi2WO6 microspheres and the photocatalytic activity in the coupling reaction between alcohols and amines under visible light irradiation
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Flower-like Bi2WO6 microspheres and bulk g-C3N4 were prepared by the hydrothermal method and high-temperature calcining method, respectively. A new method based on the combination of ultrasonic stripping and mechanical stirring was used to obtain uniform composite x-Bi2WO6/g-C3N4 (x is the Bi2WO6 mass ratio) photocatalysts with a Z-scheme heterojunction. In the reaction of benzyl alcohol and aniline to form imine, the optimal composite, 30percent-Bi2WO6/g-C3N4, showed a conversion rate of 87.6percent, which is much higher than that of pure Bi2WO6 and g-C3N4. Characterization by SEM and TEM showed that the ultrasonically stripped g-C3N4 significantly reduced the radial dimension compared to bulk g-C3N4. A uniformly dispersed photocatalytic material was formed, and it maintained a flower-like microsphere structure. Materials characterized by N2 adsorption–desorption isotherms (BET) showed that the specific surface area of the g-C3N4 nanosheets increased by approximately ten times after ultrasonic stripping. The photostability of the composite was verified by cyclic experiments. Under visible light irradiation, the activation energy of the coupling reaction between benzyl alcohol and aniline was found to be decreased by 29.8 kJ mol?1. A capture experiment was used to verify the active species in the photocatalytic system, with the reaction found to be mainly completed through the synergistic action of h+, e? and ?O2?.
- Hao, Xueli,Li, Enbo,Li, Haiying,Li, Jingyi,Wang, Yan,Wang, Zhibao,Yu, Xiujuan,Zhang, Zhiying
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- Aluminosilicates with different pores structure in the synthesis of 2,2,4-trimethyl-1,2-dihydroquinoline and N-phenyl-2-propanimine
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Physicochemical characteristics of microporous zeolites of various structural type (FAU, BEA, MTW), micro-meso-macroporous zeolite (H-Ymmm), and mesoporous aluminosilicate (ASM) were studied. Their catalytic activity in the reaction of aniline with aceton
- Grigor’eva,Filippova,Gataulin,Bubennov,Agliullin,Kutepov,Narender, Nama
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Read Online
- Room-temperature copper-catalyzed electrophilic amination of arylcadmium iodides with ketoximes
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We started our study by preparation two ketoximes. Later, there were studies to reveal these ketoximes' effects in the electrophilic amination reaction with organocadmium reagents. Primarily, it was observed that arylcadmium iodides could not be reacted with ketoximes at room temperature in the absence of a catalyst. CuCN was a suitable catalyst for this electrophilic amination reaction of arylcadmium iodides and allowed the preparation of functionalized aniline derivatives in good yields under mild reaction conditions. We obtained the results indicated that the yield of primary arylamines was strongly dependent on the steric and electronic effects of organocadmium reagent and amination agent. In the case of both amination reagents, meta-substituted arylamines were obtained in higher yields than para-substituted arylamines. We observed that acetone O-(4-chlorophenylsulfonyl)oxime, 1, as an aminating agent, was more successful than acetone O-(2-Naphthylsulfonyl)oxime, 2, in the synthesis of functionalized arylamines by electrophilic amination of corresponding aryl cadmium iodides. In this method, there is no cadmium release to the environment.
- Korkmaz, Adem
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p. 3119 - 3125
(2021/05/10)
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- Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3as a reductant
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Herein, we report the first example of efficient reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a catalyst and a reductant under mild conditions, affording various tertiary and secondary amines in excellent yields. A mechanistic study indicates that BH3N(C2H5)3 plays a dual function role of promoting imine and iminium formation and serving as a reductant in reductive amination. This journal is
- Zou, Qizhuang,Liu, Fei,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 8588 - 8591
(2021/09/04)
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- Copper-Catalyzed Intramolecular Amination of C(sp3)-H Bond of Secondary Amines to Access Azacycles
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The cross-coupling of C-N bond directly from inert C-H bonds is an ideal approach to synthesize saturated azacycles due to its high efficiency and atom economy. In this article, a copper-catalyzed intramolecular amination via the cross coupling of C(sp3)-H and N-H bonds of secondary amine has been reported, which exhibit excellent chemo- and regioselectivity, extensive substrate scope, and functional group tolerance in good to excellent yield, offering an efficient pathway to build nitrogen-containing heterocycle skeletons.
- Jin, Ruo-Xing,Dai, Jing-Cheng,Li, Yan,Wang, Xi-Sheng
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supporting information
p. 421 - 426
(2021/01/26)
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- Cu/Ni-doped sulfated zirconium oxide immobilized on CdFe2O4 NPs: a cheap, sustainable and magnetically recyclable inorgano-catalyst for the efficient preparation of α-aminonitriles in aqueous media
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Abstract: A new multifunctional bimetallic nanocatalyst was prepared by immobilization of Cu/Ni-doped sulfated zirconium oxide on magnetic cadmium ferrite (CdFe2O4@SiO2@ZrO2/SO42?/Cu/Ni) and used as an efficient recyclable catalyst for one-pot as well as stepwise preparation of α-aminonitriles under mild conditions. The magnetic nanocatalyst was characterized by FTIR, TGA, VSM, XRD, EDX, FE-SEM, and TEM analyses. Also, the surface acidity of the catalyst was measured by pyridine adsorption assay. The catalyst possesses various active sites which could catalyst a variety of aromatic and aliphatic aldehydes to the corresponding α-amionitriles under moderate to high yields in the presence of aniline. Furthermore, transformation of ketones to the desired α-amionitriles and some bis-aminonitriles was also performed by this method. The catalyst could be readily recovered from the reaction mixture and reused for several times without significant loss of activity. Graphic abstract: A general and efficient method has been developed for transformation of a variety of aliphatic, aromatic aldehydes and ketones to the corresponding α-aminonitriles using a multifunctional recyclable CdFe2O4@SiO2@ZrO2/SO42?/Cu/Ni nanocatalyst.[Figure not available: see fulltext.]
- Nasseri, Mohammad Ali,Ramezani-Moghadam, Simin,Kazemnejadi, Milad,Allahresani, Ali
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p. 4233 - 4256
(2020/07/08)
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- Synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) over selected organosulfonic acid silica catalysts: Selectivity aspects
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This paper presents investigation on the synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) as a result of the reaction of aniline and both acetone and mesityl oxide in the presence of selected sulfonic acid silica catalysts. Condensation of aniline with acetone is very complex process with the formation of significant number of side products, both desirable and undesirable considering the final product (TMQ). In acidic conditions and elevated reaction temperature the reactivity of main raw materials (aniline, acetone) is significantly high, what causes the formation of many side by-products lowering the selectivity of this reaction. In this paper the reaction of aniline with acetone in the presence of heterogeneous acidic silica catalysts were investigated in more detail and discussed. The results were confirmed by GC/MS analysis, that the presence of TMQ isomers and other by-products significantly affected the formation of final product. The formation of previously not described structural isomer of TMQ has been also demonstrated.
- Nowicki,Jaroszewska,Nowakowska-Bogdan,Szmato?a,I?owska
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- Transition-Metal-Free Addition of Acetylenes to Ketimines: the First Base-Catalyzed Ethynylation of the C=N Bond
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A one-pot transition metal-free synthesis of propargylamines in good to excellent yield from ketone-derived imines and aryl- and hetarylacetylenes in the presence of KOBut/DMSO superbase system (40 °C, 10 min) has been developed. The reaction i
- Bidusenko, Ivan A.,Schmidt, Elena Yu.,Ushakov, Igor A.,Trofimov, Boris A.
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supporting information
p. 4845 - 4849
(2018/09/14)
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- Silver-Catalyzed Three-Component 1,1-Aminoacylation of Homopropargylamines: α-Additions for Both Terminal Alkynes and Isocyanides
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The reaction of secondary homopropargylamines, isocyanides, and water in the presence of a catalytic amount of silver acetate and subsequent purification by chromatography on silica gel afforded substituted proline amides in good to excellent yields. Primary homopropargylamines underwent a cyclizative Ugi–Joullié three-component reaction with isocyanides and carboxylic acids to afford functionalized N-acyl proline amides. High diastereoselectivity was observed in the synthesis of 4-alkoxy and 4,5-disubstituted proline derivatives. This work represents the first examples of a three-component cyclizative 1,1-aminoacylation of terminal alkynes.
- Tong, Shuo,Piemontesi, Cyril,Wang, Qian,Wang, Mei-Xiang,Zhu, Jieping
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supporting information
p. 7958 - 7962
(2017/06/27)
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- Aryl C-N bond formation by electrophilic amination of diarylcadmium reagents with O-substituted ketoximes
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Diorganocadmium reagents cannot react with ketoxime at room temperature. CuCN catalysis allows diarylcadmium reagents to react with ketoxime and to give corresponding arylamines in good to high yields at room temperature. According to the electronic effects of the substituent attached to the aromatic ring, functionalized diarylcadmium reagents show meta-para selectivity in their amination reactions. Also compared to diarylzinc reagents, diarylcadmium reagents react with O-substituted ketoxime under milder reaction conditions and they form corresponding arylamines in higher yields. CuCN cannot help dialkyl-, dicycloalky-, and dibenzylcadmium reagents to react with ketoxime. Our Aryl C-N bond formation method does not include cadmium excretion into the environment.
- Da?kapan, Tahir,Korkmaz, Adem
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p. 813 - 817
(2016/07/06)
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- P-Tolylimido rhenium(v) complexes-synthesis, X-ray studies, spectroscopic characterization, DFT calculations and catalytic activity
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Novel p-tolylimido rhenium(v) complexes trans-(Cl,Cl)-[Re(p-NC 6H4CH3)Cl2(py-2-COO)(PPh 3)]·MeCN (1a), trans-(Cl,Cl)-[Re(p-NC6H 4CH3)Cl2(py-2-COO)(PPh3)] (1b), trans-(Br,Br)-[Re(p-NC6H4CH3)Br 2(py-2-COO)(PPh3)] (2), cis-(Cl,Cl)-[Re(p-NC 6H4CH3)Cl2(py-2-COO)(PPh 3)] (3), cis-(Br,Br)-[Re(p-NC6H4CH 3)Br2(py-2-COO)(PPh3)]·H2O (4), trans-(Cl,Cl)-[Re(p-NC6H4CH3)Cl 2(OMe)] (5) and trans-(Br,Br)-[Re(p-NC6H 4CH3)Br2(OMe)(PPh3) 2]·1/2H2O (6) were synthesized. The compounds were identified by elemental analysis, IR, NMR (1H, 13C and 31P), UV-Vis spectroscopy and X-ray crystallography. Calculations at the DFT level were undertaken in order to elucidate the structural, spectroscopic and bonding properties of the trans-(Cl,Cl) and cis-(Cl,Cl) isomers of [Re(p-NC6H4CH3)Cl 2(py-2-COO)(PPh3)]. In the first step, extended tests of the ability of different DFT methods (B3LYP, BP86, and PBE1PBE) were performed to find the best overall performer in describing the geometry of the imido Re(v) complexes; then, the electronic spectra of the trans and cis isomers of [Re(p-NC6H4CH3)Cl2(py-2-COO) (PPh3)] were investigated at the TDDFT level employing the PBE1PBE functional. Additional information about bonding in the compounds [Re(p-NC 6H4CH3)Cl2(py-2-COO)(PPh 3)] was obtained by NBO analysis. The catalytic activity of the complexes incorporating the picolinate ligand was studied and compared in the synthesis of N-substituted ethyl glycine esters from ethyl diazoacetate and amines.
- Machura, Barbara,Gryca, Izabela,Malecki, Jan Grzegorz,Alonso, Francisco,Moglie, Yanina
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p. 2596 - 2610
(2014/02/14)
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- New approaches to photocatalytic reaction of low concentrations of arylamines in alcohols
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Photocatalytic interactions of a series of arylamines, for example 1,4- phenylenediamine, 1,2-phenylenediamine, 4-aminophenol, and 2-aminophenol, at low concentrations in typical primary alcohols have been investigated in the presence of anatase TiO2 nanopowder. GC-MS analysis of the irradiated solutions showed that, except for 1,2-phenylenediamine, 10 mmol/l alcoholic solutions of the arylamines gave predominately the corresponding imines. Irradiation of 2-aminophenol under these conditions, led to oxidation and dimerization to 2-amino-3Hphenoxazin- 3-one. Springer Science+Business Media B.V. 2012.
- Hosseinnia, Azarmidokht,Keyanpour-Rad, Mansoor
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p. 1411 - 1420
(2012/11/07)
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- Discovery of novel quaternary ammonium derivatives of (3R)-quinuclidinyl carbamates as potent and long acting muscarinic antagonists
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Novel quaternary ammonium derivatives of N,N-disubstituted (3R)-quinuclidinyl carbamates have been identified as potent M3 muscarinic antagonists with long duration of action in an in vivo model of bronchoconstriction. These compounds have also presented a high level of metabolic transformation (human liver microsomes). The synthesis, structure-activity relationships and biological evaluation of these compounds are reported.
- Prat, Maria,Buil, María Antonia,Fernández, Maria Dolors,Castro, Jordi,Monleón, Juan Manuel,Tort, Laia,Casals, Gaspar,Ferrer, Manuel,Huerta, Josep Maria,Espinosa, Snia,López, Manuel,Segarra, Victor,Gavald, Amadeu,Miralpeix, Montserrat,Ramos, Israel,Vilella, Dolors,González, Marisa,Córdoba, Mnica,Cárdenas, Alvaro,Antón, Francisca,Beleta, Jorge,Ryder, Hamish
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scheme or table
p. 3457 - 3461
(2011/06/24)
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- Modular synthesis of indoles from imines and o-dihaloarenes or o-chlorosulfonates by a Pd-catalyzed cascade process
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A detailed study of the scope of a new Pd-catalyzed synthesis of indolesfrom 1,2-dihaloarenes and o-halobenzene sulfonates and imines is descri bed. The cascade reaction comprises an imine a-arylation ollowed by an intramolecular C-N bond-forming reaction promoted by the same Pd catalyst. The reaction with 1,2-dibromobenzene shows wide scope and allows the introduction of aryl, alkyl, and vinyl substituents at different positions of the five-membered ring of the indole. The regioselective synthesis of indoles substituted in the six-membered ring can be carried out by employing o-dihalobenzene derivatives with two different halogens, taking advantage of the different reactivities of I, Br, and Cl in oxidative addition reactions. This paper also introduces a method for the efficient cleavage of the N-t-butyl group, thus allowing for the preparation of N-H indoles through the same methodology. Finally, the reaction with o-halosulfonates has been studied. The best substrates are o-chlorononaflates, which lead to indoles in very high yield. The reaction is particularlyappropriate for the synthesis of the challenging 6-substituted indoles. In view of the availability of o-chlorophenols, which are direct precur sors of the chlorononaflates, this reaction represents an efficient entry into indoles substituted in the six-membered ring. The concept is illustrated by the preparation of a 4,6-disubstituted indole from naturally occurring anethole.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Aznar, Fernando,Valdes, Carlos
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supporting information; experimental part
p. 4031 - 4041
(2009/09/04)
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- Silica gel supported sodium hydrogen sulfate as an efficient and reusable heterogeneous catalyst for the synthesis of imines in solvent-free conditions under microwave irradiation
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This synthesis of imines has been carried out efficiently by the condensation of carbonyl compounds with amines in the presence of silica gel supported sodium hydrogen sulfate (NaHSO4.SiO2) as a heterogeneous catalyst under microwave irradiation in solvent-free conditions. NaHSO4.SiO2 can be recovered and re-used up to ten times by simple washing with diethyl ether after each use and activated in an oven at 120°C for 1 h, thus rendering the process more economical.
- Gopalakrishnan, Mannathusamy,Sureshkumar, Purushothaman,Kanagarajan, Vijayakumar,Thanusu, Jeyaraman,Govindaraju, Ramalingam
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p. 299 - 303
(2007/10/03)
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- Scope and mechanistic study of the ruthenium-catalyzed ortho-C-H bond activation and cyclization reactions of arylamines with terminal alkynes
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The cationic ruthenium hydride complex [(PCy3) 2(CO)(CH3CN)2RuH]+BF 4- was found to be a highly effective catalyst for the C-H bond activation reaction of arylamines and terminal alkynes. The regioselective catalytic synthesis of substituted quinoline and quinoxaline derivatives was achieved from the ortho-C-H bond activation reaction of arylamines and terminal alkynes by using the catalyst Ru3-(CO)12/HBF 4·OEt2. The normal isotope effect (k CH/kCD = 2.5) was observed for the reaction of C 6H5NH2 and C6D5NH 2 with propyne. A highly negative Hammett value (ρ = -4.4) was obtained from the correlation of the relative rates from a series of meta-substituted anilines, m-XC6H4NH2, with σp in the presence of Ru3(CO)12/ HBF4·OEt2 (3 mol % Ru, 1:3 molar ratio). The deuterium labeling studies from the reactions of both indoline and acyclic arylamines with DC≡CPh showed that the alkyne C-H bond activation step is reversible. The crossover experiment from the reaction of 1-(2-amino-1-phenyl)pyrrole with DC≡CPh and HC≡CC6H4-p-OMe led to preferential deuterium incorporation to the phenyl-substituted quinoline product. A mechanism involving rate-determining ortho-C-H bond activation and intramolecular C-N bond formation steps via an unsaturated cationic ruthenium acetylide complex has been proposed.
- Yi, Chae S.,Yun, Sang Young
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p. 17000 - 17006
(2007/10/03)
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- Can we aminate Grignard reagents under Barbier conditions?
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The reaction of aryl bromides with acetone O-(2,4,6-trimethylphenylsulfonyl)oxime and magnesium in THF at reflux temperature for 3 h provides a one-pot procedure for amination of aryl Grignard reagents under Barbier conditions.
- Erdik, Ender,Da?kapan, Tahir
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p. 6237 - 6239
(2007/10/03)
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- KINETICS OF HYDROGENATION AMINATION OF 2-PROPANOL WITH ANILINE ON A COPPER-CHROMIUM CATALYST
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The kinetics of hydrogenation amination of alcohols in the liquid phase were studied in the presence of a copper(II)-chromium(III) catalyst, 2-propanol and aniline were used as the models.In addition to the kinetic investigation of the model reaction as a whole, the partial reaction steps - dehydrogenation of 2-propanol and condensation of aniline with acetone - were also examined.It was proved that, in the reaction of aniline with 2-propanol on the copper-chromium catalyst, the formation of acetone is equilibrium-controlled.The overall rate of amination of 2-propanol with aniline is determined by both the condensation of acetone with aniline and the hydrogenation of the ketimine intermediate.The amination is accelerated by addition of aluminosilicate to the copper-chromium catalyst, which confirms that the ketimine concentration is not equilibrium-controlled.
- Dlouhy, Jiri,Pasek, Josef
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p. 326 - 340
(2007/10/02)
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- THERMAL Z,E-ISOMERIZATION OF IMINES. IV. ANILS OF ACETONE
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It has been established by the correlation between the values of log k298 and the ? constants that the degenerate thermal Z,E-isomerization of anils of acetone takes place according to an inversion mechanism, with the exception of acetone p-dimethylaminophenylimine, which isomerizes predominantly according to a rotation mechanism.The increase in the steric stresses upon the introduction of ortho substituents into the aryl ring of anils of acetone results in significant lowering of the barriers to the inversion of the nitrogen atom.The raising of the barriers to inversion in phenylimines as the electron-acceptor properties of the substituents on the imino carbon atom are enhanced is due to the weakening of the n?N-?*Ph interaction as a consequence of the increase in the energy gap between the interacting orbitals as a result of the lowering of the energy of the n?N orbital.
- Prosyanik, A. V.,Kol'tsov, N. Yu.,Romanchenko, V. A.
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p. 1330 - 1337
(2007/10/02)
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- The Pyrolysis of N-Allyl Compounds: Free-radical and Retro-ene Mechanisms
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Flash vacuum pyrolysis of N-alkyl-N-allylanilines gives imines by free radical cleavage of the allyl group followed by loss of an atom (or group of atoms) from the α-carbon atom of the alkyl group.The corresponding N-propargyl derivatives also give imines on pyrolysis, but the mechanism is a concerted retro-ene process which may lead to different products from the corresponding N-allyl compound.N-Allyl-N,N-dialkylamines also decompose thermally by a retro-ene process
- Cadogan, J. I. G.,Hickson, Clare L.,McNab, Hamish
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p. 2247 - 2273
(2007/10/02)
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- Thermolysis of 5,5-dimethyl-4-aryl-Δ1-1,2,4-triazolin-3-ones in solution. Products, kinetics, substituent effects, and solvent effects
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A series of 5,5-dimethyl-4-Δ1-1,2,4-triazolin-3-ones (Ar=C6H5, p-C6H4CH3, p-C6H40CH3,p-C6H4Cl, and p-C6H4Br) were prepared from the corresponding 4-arylsemicarbazones of acetone by oxidative cyclization on alumina.The triazolines decompose in solution to N2,CO, and isopropylidene aryl amine, with first order kinetics, in the temperature range 148-200 deg C.Average activation parameters are ΔH*=35 kcal*mol-1 and ΔS*=8 cal*K-1*mol-1.Substituent effects are correlated through Σ-constants but the thermolyses are relatively insensitive to substituents, with p=-0.17 at 172.5 deg C.Solvent effects indicate a transition state that is less polar than the ground state.It is tentatively concluded that the triazolinone fragmentation, like the analogous thermolysis of a Δ3-1,3,4-oxadiazolin-2-one, may be a fully-concerted but nonsynchronous process with a transition state involving little, if any, charge separation.Other mechanisms, except for those involving highly polar (e.g. zwitterionic) transition states, have not been ruled out.
- Cabelkova-Taguchi, Lubomira M.,Warkentin, John
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p. 100 - 105
(2007/10/02)
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- Photolysis of 5,5-dimethyl-4-phenyl-Δ1-1,2,4-triazolin-3-one. Fragmentation to nitrogen, carbon monoxide, and isopropylidene phenyl amine
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Photolysis of 5,5-dimethyl-4-phenyl-Δ1-1,2,4-triazolin-3-one (2) produces the same products as thermolysis; namely, nitrogen, carbon monoxide, and isopropylidene phenyl amine (acetone anil).The quantum yield for direct photolysis of 2 in methanol with 313 nm light is 0.066.Sensitization with benzophenone in the same solvent, and quenching with 1,3-cyclohexadiene, revealed that photolysis of 2 involves a triplet excited state.The most likely photo processes are thought to involve initial cleavage of the C3-N4 bond or the C3-N2 bond (Norrish, type 1 cleavage).
- Cabelkova-Taguchi, Lubomira M.,Warkentin, John
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p. 3087 - 3089
(2007/10/02)
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- New Olefin and Oxiran Syntheses from Carbonyl Compounds, and Diethyl Sodiophosphonate Anions and 1-Aminophosphonate Amino-anions
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Reaction of aromatic aldehydes, and phthalic and thiophthalic anhydrides, with diethyl sodiophosphonate (1) gives the trans-stilbenes (3), 3,3'-biphthalidylidene (30), and 3,3'-bis-(2-thiophthalidylidene) (33).Similar treatment of fluorenone (8) and xanthone (17) with (1) leads to 9,9'-bis(fluororenylidene) (9) and 9,10-dihydro-9-oxophenanthrene-10-spiro-9'-fluorene (10), and to 9,9'-bixanthenylidene (18) and 9,9'-bixanthenyl (19), respectively, but the reaction using anthrone (11) as a carbonyl reagent yields only anthraquinone (12) and anthracene (13).Similar treatment using N-methylisatoic anhydride (34) and N-methylisatin (36) produces NN'-dimethylisoindigo (35).Reaction of benzaldehyde and p-chlorobenzaldehyde with diethyl 1--cyclohexylphosphonate (40) gives mainly corresponding mixtures of trans- (41a,b) and cis-stilbene epoxides (42a,b), while similar treatment of p-nitrobenzaldehyde with (40) produces 4,4'-dinitrostilbene (3e).Reaction of (8) with (40), as well as with (1), gives (9) and (10).The mechanism of formation of these products is discussed.
- Minami, Toru,Matsuzaki, Narihide,Ohshiro, Yoshiki,Agawa, Toshio
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p. 1731 - 1738
(2007/10/02)
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- Photolysis of Alkyl Azides. Evidence for a Nonnitrene Mechanism
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The photolyses of nine sec- and tert-alkyl azides have been studied in detail.The products consist of imines derived from 1,2-shifts of groups on the alkyl carbon atom α to the azide nitrogen atom.No evidence of typical nitrene processes (aromatic substitution, aliphatic C-H insertion) was found.The imine product distributions are rationalized on the basis of a preferred migration orientation in the photochemically excited azide, along with a consideration of either ground or excited state rotational equilibration of the azide.Photolyses of selected azides carried out over an approximately 200 deg C temperature range allow an estimation of apparent activation energy differences between different group migrations.These energy differences are in the range of 70-493 cal/mol and are related to rotational equilibration of the alkyl azide.
- Kyba, Evan P.,Abramovitch, Rudolph A.
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p. 735 - 740
(2007/10/02)
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