- Framework-Substituted Sn-MOR Zeolite Prepared by Multiple pH-Adjusting Сo-Hydrolysis As Efficient Catalyst for tert-Butylation of Toluene
-
Abstract: A series of Sn-MOR samples with different tin species loadings were prepared via a mutiple pH?adjusting co-hydrolysis method. Their properties were characterized by XRD, XRF, UV–Vis, FT-IR, Py-IR, N2 sorption and SEM techniques. The catalytic performance was evaluated in liquid-phase toluene alkylation with tert-butyl alcohol. The characterization results shows that compared to framework destruction of mordenite for the Sn/MOR sample with floccule prepared by ion exchange method, higher relative crystallinity and larger surface area and pore volume for Sn-MOR samples with walnut morphology can be obtained. The doping with tin species can increase the Lewis acidity and decrease the pore size resulting in both higher toluene conversion and p-tert-butyltoluene (PTBT) selectivity. The Sn-MOR(0.010) sample shows the highest catalytic performance with toluene conversion of 48.0% and PTBT selectivity of 85.6%. It?shows high stability: toluene conversion of 45.3% and PTBT selectivity of 87.2% can be obtained even after 5 consecutive runs.
- Fuling Cheng,Zhou, Zhiwei,Qin, Juan,Li, Dong,Wang, Jianzong,Wu, Wenliang
-
p. 2640 - 2646
(2019/02/28)
-
- Tert-Butylation of toluene with tert-butyl alcohol over immobilized titanium species on the Al-MCM-48
-
A series of Ti-Al-M48 (M48 stand for MCM-48) samples with different titanium species loadings were prepared by immobilization method. Their physical chemical properties were characterized by XRD, liquid N2 adsorption-desorption, Py-IR, NH3-TPD and UV-vis DRS techniques, and their catalytic performances were investigated in the tert-butylation of toluene with tert-butyl alcohol in a 100 ml stainless steel autoclave equipped with a magnetically driven impeller. The Ti-Al-M48 samples have a large BET surface and ordered mesoporous structure. Although the titanium species loading is the same, the 4% Ti-Al-M48 sample has a larger acid amount than the 4% Ti/Al-M48 sample prepared by impregnation. The Py-IR and UV-vis DRS spectra revealed that the isolated TiO4 tetrahedra by isomorphous substitution into the Al-M48 network have Lewis acidity. The 4% Ti-Al-M48 has a higher catalytic performance than other samples and the influence of reaction conditions on the tert-butylation of toluene was discussed. The conversion of toluene is 47.5% and the selectivity of p-tert-butyltoluene is 77.2% at the molar ratio of tert-butyl alcohol to toluene 2, the weight ratio of toluene to catalyst 8, reaction temperature 453K and reaction time 4 h. The 4% Ti-Al-M48 sample shows high stability, and toluene conversion 43.7% and p-tert-butyltoluene selectivity 78.4% can be obtained even though after repeated reaction for 3 times.
- Zhou, Zhiwei,Mao, Wei,Qin, Juan,Han, Tianpeng,Han, Chaofan,Wu, Wenliang
-
p. 132 - 137
(2015/08/25)
-
- Catalytic Asymmetric Hydroalkenylation of Vinylarenes: Electronic Effects of Substrates and Chiral N-Heterocyclic Carbene Ligands
-
An asymmetric tail-to-tail cross-hydroalkenylation of vinylarenes with terminal olefins was achieved by catalysis with NiH complexes bearing chiral N-heterocyclic carbenes (NHCs). The reaction provides branched gem-disubstituted olefins with high enantioselectivity (up to 94% ee) and chemoselectivity (cross/homo product ratio: up to 99:1). Electronic effects of the substituents on the vinylarenes and on the N-aryl groups of the NHC ligands, but not a π,π-stacking mechanism, assist the steric effect and influence the outcome of the cross-hydroalkenylation.
- Ho, Chun-Yu,Chan, Chun-Wa,He, Lisi
-
supporting information
p. 4512 - 4516
(2015/04/14)
-
- Nickel-catalyzed hydrodehalogenation of aryl halides
-
In the present study, the nickel-catalyzed dehalogenation of aryl and alkyl halides with iso-propyl zinc bromide or tert-butylmagnesium chloride has been examined in detail. With a straightforward nickel complex as pre-catalyst good to excellent yields and chemoselectivities were feasible for a variety of aryl and alkyl halides.
- Weidauer, Maik,Irran, Elisabeth,Someya, Chika I.,Haberberger, Michael,Enthaler, Stephan
-
supporting information
p. 53 - 59
(2013/08/25)
-
- PROCESS FOR THE PREPARATION OF M-SUBSTITUTED ALKYLTOLUENES BY ISOMERIZATION WITH IONIC LIQUIDS AS CATALYSTS
-
The invention relates to a process for the preparation of m-substituted alkyltoluenes of the formula (I) in which R1 is C1-C5-alkyl, wherein a p-substituted alkyltoluene of the formula (II) in which R1 has the meaning given under formula (I), is isomerized in the presence of ionic liquids to give an m-substituted alkyltoluene of the formula (I). The m-substituted alkyltoluenes obtainable according to the invention are starting compounds for the preparation of fragrances and aroma substances.
- -
-
Page/Page column 3
(2011/08/22)
-
- Easier preparation of 2,6-Di-tert-butylphenyl derivatives 1
-
Despite steric shielding by the 2,6-di-tert-butylphenyl group (super-2,6-xylyl=xyl*), inexpensive sodium phenolate (xyl*-ONa) reacts with dimethyl sulfate to produce only xyl*-OCH3 (94%) with complete suppression of the alternative 4-methylation. Reductive cleavage of xyl*-OCH3 by elemental lithium with the help of an electron carrier generates xyl*-Li, which in turn yields xyl*-CO2H (63%). The corresponding 4-methyl-derivatives of these compounds were obtained analogously. The acid chloride xyl*-COCl (77% yield) acylates HalMgCH 2R to give only xyl*-COCH3 (86%) or xyl*-COEt (97%). These two ketones react with n-butyllithium (no carbonyl addition) and Cl-PO(OEt)2 to furnish only the enol phosphates xyl*-C(=CH 2)OPO(OEt)2 (84%) or xyl*-C(=CHCH 3)OPO(OEt)2 (up to 70%), respectively. Only 1,2-elimination occurs when the latter two products are treated with tert-butyllithium, affording xyl*-CCH (68%) or xyl*-CCMe (88%), respectively. Georg Thieme Verlag Stuttgart - New York.
- Knorr, Rudolf,Rossmann, Eva Christine,Knittl, Monika
-
scheme or table
p. 2124 - 2128
(2010/09/04)
-
- Determination of critical temperatures for mixtures of alkylbenzenes
-
The liquid-vapor critical temperatures of benzene mixtures with 1,3-di-tert-butylbenzene, 1,4-di-tert-butylbenzene, and 1,3,5-tri-tert- butylbenzene; a mixture of di-tert-butylbenzene isomers; and a toluene mixture with 3,5-di-tert-butyltoluene were determined over the entire range of composition by means of the amouule method. It was found that the excess critical temperature of the mixtures is related to the critical volumes of the substances. The capabilities of several calculation methods for predicting the critical temperature of mixtures were analyzed on the basis of published data and the obtained results. The Lee-Kesler rules of mixtures were refined by introducing binary interaction parameters.
- Nesterov,Nazmutdinov,Sarkisova,Nesterova,Vodenkova
-
p. 434 - 441
(2008/09/16)
-
- Unusual demethylation of O,O′-dimethyl chlorothiophosphate with aryllithiums
-
The reaction of O,O′-dimethyl chlorothiophosphate with aryllithiums took place easily to afford the corresponding methylated aryl compounds in place of expected O,O′-dimethyl aryl(thiophosphonate)s. Copyright
- Ribeiro, Nigel,Maeda, Jin,Ishida, Yasuhiro,Kobayashi, Yuka,Saigo, Kazuhiko
-
p. 1412 - 1413
(2008/03/14)
-
- Palladium-catalyzed benzannulation from alkynes and allylic compounds
-
Various alkynes reacted with allyl tosylates in the presence of palladium catalysts, giving polysubstituted benzenes with good to high regioselectivity. Pentasubstituted and trisubstituted benzenes were readily prepared by reaction of internal alkynes and
- Tsukada, Naofumi,Sugawara, Shuichi,Nakaoka, Keiichiro,Inoue, Yoshio
-
p. 5961 - 5966
(2007/10/03)
-
- A new synthetic route to donor-acceptor porphyrins
-
Some new donor-acceptor porphyrins have been prepared based on a metallated bis(ethynyl) porphyrin core. 4-(Dimethylamino)phenyl was used as the donor group and 4-nitrophenyl, 4-cyanophenyl and 5-nitrothiazoyl as the acceptor groups. Dipyrrylmethane was used for large scale porphyrin ring synthesis because the absence of methylene substituents reduces the difficulty of substituent scrambling that occurs during porphyrin synthesis.
- Plater, M.John,Aiken, Stuart,Bourhill, Grant
-
p. 2405 - 2413
(2007/10/03)
-
- Synthesis of (S,S)-1,2-bis(3,5-di-tert-butylphenyl)ethane-1,2-diol
-
The synthesis of (S,S)-1,2-bis(3,5-di-tert-butylphenyl)ethane-1,2-diol (98.6% ee), which should be useful as a chiral ligand of catalysts in asymmetric inductions, is described.
- Ishimaru, Kaori,Monda, Keiji,Yamamoto, Yohsuke,Akiba, Kin-Ya
-
p. 575 - 580
(2007/10/03)
-
- Electrochemical oxidation of probucol in anhydrous acetonitrile
-
Electrochemical oxidation of probucol in anhydrous acetonitrile was studied as a model of the metabolic oxidation of the substance. The study was performed by DC voltammetry, potentiostatic coulometry, cyclic voltammetry and preparative electrolysis. Probucol gives a single anodic wave E1/2 = 0.92 V. Cyclic voltammetry showes that its electrooxidation proceeds by formation of probucol radical. 2,6-Di-tert-butyl-4-(isopropylsulfanyl)phenol, 2,6-di-tert-butyl-4-sulfanylphenol, 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butylphenol were isolated as products of electrochemical oxidation.
- Nesmerak, Karel,Nemec, Ivan,Sticha, Martin,Gabriel, Jiri,Mirceski, Valentin
-
p. 1100 - 1110
(2007/10/03)
-
- Polyenylidene thiazolidine derivatives with retinoidal activities
-
Several polyenylidene thiazolidinedione or 2-thioxo-4-thiazolidinone derivatives were synthesized and their retinoidal activities were examined in terms of the differentiation-inducing ability towards human promyelocytic leukemia HL-60 cells and inhibitory effect on interleukin (IL)-1α-induced IL-6 production in MC3T3-E1 cells. Compounds containing a trimethylcyclohexenyl ring induced HL-60 cell differentiation with weaker activity than retinoic acid (1a) by one or two orders of magnitude. The thiazolidinedione derivatives (2, 5, 7) showed stronger activity than the corresponding 2-thioxo-4-thiazolidinone derivatives (3, 6, 8). The effects of a retinoid antagonist (LE540) and synergists (retinoid X receptor (RXR) agonists, HX600 or HX630) on the activities of thiazolidine derivatives indicate that these compounds elicit their activities through the nuclear retinoic acid receptors (RARs). All the thiazolidines examined also inhibited IL-1α-induced IL-6 production with IC50 values of 10nM order. The retinoidal activities of the thiazolidines are significant, considering that replacement of the carboxylic acid in retinoid structures with bioisosteric functional groups is generally ineffective, as seen in the structure-activity relationships of retinoidal benzoic acids.
- Tashima, Toshihiko,Kagechika, Hiroyuki,Tsuji, Motonori,Fukasawa, Hiroshi,Kawachi, Emiko,Hashimoto, Yuichi,Shudo, Koichi
-
p. 1805 - 1813
(2007/10/03)
-
- 3,5-Di-tert-butylstyrenes: Synthesis of Bulky Polymer Building Blocks
-
We report the synthesis of 3,5-di-tert-butylstyrene (5).The alkylation of toluene with tert-butylchloride establishes the 1,3,5-substitution pattern.A Wittig reaction introduces the C1 unit.This and similar bulky styrene derivatives will be used as special building blocks for polymer design. - Keywords: 3,5-Di-tert-butylstyrenes, Bulky Polystyrene Monomers, 1H NMR Spectra
- Risch, Nikolaus,Meyer-Roscher, Bernd,Langhals, Maria
-
p. 141 - 144
(2007/10/02)
-
- Photolysis of (2,4,6-Tri-t-butylphenyl)bis(trimethylsilyl)phosphine
-
The photolysis of (2,4,6-tri-t-butylphenyl)bis(trimethylsilyl)phosphine in benzene gave products suggesting homolytic P-C bond cleavage followed by rearrangement and coupling.
- Yoshifuji, Masaaki,Shimura, Kazuho,Toyota, Kozo
-
p. 1980 - 1983
(2007/10/02)
-
- C-(N,N-DIALKYLAMINO)-SUBSTITUTED ARSAALKENES: A SIMPLE METHOD FOR THE PREPARATION AND EXAMPLES OF THEIR REACTIVITY
-
A simple method for the preparation of C-(N,N-dialkylamino)-substituted arsaalkenes 4a, b is suggested.The -As=C bond in this kind of compounds is shown to react with sulfur to yield dithioarsaranes, which are dimeric in the solid phase and monomeric in the gas phase.Key words: Arsine; amidacetals; arsaalkenes; dithioarsaranes.
- Ionkin, A. S.,Nikolaeva, N. V.,Musin, R. Z.,Efremov, Yu. Ya.,Arbuzov, B. A.
-
p. 257 - 260
(2007/10/02)
-
- VARIABLE TEMPERATURE ESR SPECTRA OF 1-(3,4,5-TRIMETHOXY-BENZOYL)-2,2-BIS(3,5-DI-TERT-BUTYL-PHENYL)HYDRAZYL AND ITS 1-(15)N-CONGENER
-
The title free radicals were obtained by oxidation of the corresponding hydrazines which were synthesized and characterized by elemental analysis, IR and 1H-NMR spectra. The ESR spectra of the free radicals were recorded in toluene in the temperature range -50 deg C to +90 deg C. The simulated ESR spectra indicate a higher spin density at the tricoordinated N-2 nitrogen of the diarylamino group (hfc aN = 0.862 mT) than at the dicoordinated N-1 nitrogen atom (hfc aN = 0.830 mT). In the temperature range 0 deg C to 30 deg C the activation free energy for interconversion of conformers was determined to be ΔG(excit.) = 7.80 kcal/mol.
- Crasovschi, Afanase,Grecu, Nicoleta,Negoita, Nicolae,Caproiu, Miron Teodor,Balaban, Alexandru T.
-
p. 1335 - 1340
(2007/10/03)
-
- Factors Affecting the Stability and Equilibria of Free Radicals. 14. Unexpected Spin Densities in 1-(Trifluoroacetyl)-2,2-diarylhydrazyl Revealed by 15N Labeling
-
1-(Trifluoroacetyl)-2,2-bis(3,5-di-tert-butylphenyl)hydrazyl and its congener labeled at the dicoordinated 1-nitrogen atom with 15N were prepared.ESR spectra of solutions of both compounds were recorded and hyperfine coupling constants determined by optimizing simulated spectra.Unlike all other 1,2,2-triarylhydrazyls which have been investigated, the hyperfine coupling constant for the dicoordinated nitrogen is lower (0.7 mT) than that for the tricoordinated nitrogen (1.0 mT) in this free radical.This striking result raises questions about the mode of trifluoroacetyl group participation in ? electron delocalization.
- Bologa, Ursula,Balaban, Alexandru T.,Grecu, Nicoleta,Negoita, Nicolae,Caproiu, Miron T.,Walter, Robert I.
-
p. 4176 - 4179
(2007/10/02)
-
- Crystal and Molecular Structure of Tetraaryl-3,7-diazabicyclononanes and Tetra- and Pentaaryl-1,3-diazaadamantanes. Chair-Boat Conformation of the Tetraaryl-3,7-diazabicyclononanes
-
The 2,4,6,8-tetrakis(3,5-dimethylphenyl)-3,7-diazabicyclononanes 8c and 10c, the 1,3-diazaadamantanes 11c and 13c derived therefrom, and some tetraaryl-3,7-diazabicyclononanes methylated at one (14b, 16b) or both nitrogen atoms (15b, c, 17b, c, 19) have been synthesized for structure and NMR studies.N-Methylation occured regioselectively at the piperidine ring existing in the boat conformation.The nitrogen atom of the piperidine ring in the chair conformation was methylated only under forced conditions.With 4-methylbenzaldehyde, 8b formed slowly the pentakis(4-methylphenyl)-1,3-diazaadamantanone 12b, in which the configuration of one of the benzylic carbon atoms of the piperidine ring in the chair conformation had changed.By means of X-ray analysis of the 3,7-diazabicyclononanes 8c, 15b, and 16b as well as of the 1,3-diazaadamantanones 12b and 20 the structures were determined and the preferred conformations, especially those of the aryl groups, in the crystalline state were established.Accordingly, all tetraaryl-3,7-diazabicyclononanes exist in the chair-boat conformation with equatorial aryl groups.Two of the five aryl substituents in 12b occupy a 1,3-diaxial position while the three neighbouring aryl groups exhibit an unexpected propeller-like arrangement.
- Quast, Helmut,Mueller, Bodo,Peters, Eva-Maria,Peters, Karl,Schnering, Hans Georg von
-
p. 3631 - 3652
(2007/10/02)
-