557-17-5Relevant articles and documents
Specific features of solvation effects in monomolecular and bimolecular solvolysis
Ponomarev,Michkov,Dvorko
, p. 591 - 598 (2001)
A method was suggested for distinguishing monomolecular and bimolecular solvolysis on the basis of reaction kinetics in water, MeOH, EtOH, i-PrOH, cyclohexanol, and t-BuOH. In solvolysis of n-PrBr, CH2=CHCH2Br, PhCOCl, and MeOClO3 (SN2 reactions), a linear correlation is observed between log k and the solvent ionizing power Z, whereas in solvolysis of t-BuBr, t-BuCl, and 1-AdI (SN1, E1 reactions) this correlation is nonlinear. Deviations from linearity are due to steric hindrance decreasing the negative effect of nucleophilic solvation.
Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
Geng, Jiao,Hu, Xingbang,Liu, Qiang,Wu, Youting,Yang, Liu,Yao, Chenfei
, p. 3685 - 3690 (2021/05/31)
Two strategies were reported to prevent the deactivation of Frustrated Lewis pairs (FLPs) in the hydrogenation of terminal alkynes: reducing the Lewis acidity and polymerizing the Lewis acid. A polymeric Lewis acid (P-BPh3) with high stability was designed and synthesized. Excellent conversion (up to 99%) and selectivity can be achieved in the hydrogenation of terminal alkynes catalyzed by P-BPh3. This catalytic system works quite well for different substrates. In addition, the P-BPh3 can be easily recycled.
Tailoring Interfacial Lewis Acid-Basic Pair on ZnO/4Mg1ZrOx Allows Dehydrogenative α-Methylenation of Alcohols with Methanol to Allylic Alcohols
Fu, Aixiao,Jiang, Shifeng,Liu, Qiang,Liu, Xiaoran,Liu, Xiuyun,Mu, Xindong,Sun, Mengqing,Wang, Xicheng,Xu, Guoqiang,Zhao, Lingling
, (2020/10/07)
Allylic alcohols are the essential building blocks widely used in diverse streams of organic inventions for pharmaceuticals, fragrances, agrochemicals and polymers. Currently, allylic alcohols are industrially produced from petroleum-based feedstocks via atom uneconomic processes. More sustainable synthesis route for allylic alcohols is limited. Herein, a methodology for the direct and highly selective production of allylic alcohols has been accomplished by controlled dehydrogenative α-methylenation of alcohols with methanol. This transformation is enabled by interfacial Lewis acid-basic pair on tailor-made ZnO/4Mg1ZrOx mixed oxide. High selectivity (83～92%) of allylic alcohols is the consequence of alcohols acceptorless dehydrogenation to liberation of H2 and Meerwein-Ponndorf-Verley type hydrogen transfer onto C = O bonds of unsaturated aldehydes. Furthermore, the prepared ZnO/4Mg1ZrOx mixed oxide shows good stability after 200 h time on stream test. These observations could additionally allow us to design multifunctional solid acid-basic catalysts for the transformations of renewable oxygenates into value-added chemicals.
Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
supporting information, p. 6940 - 6944 (2018/05/14)
Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring-closing reactions. Herein, we report an iron-catalyzed ring-closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.
On the miscibility of ethers and perfluorocarbons. An experimental and theoretical study
Babiak, Peter,Němcová, Adriana,Rulí?ek, Lubomír,Beier, Petr
, p. 397 - 401 (2008/12/21)
Despite their significant polar character, some organic ethers such as diethyl ether were found to be miscible with perfluorocarbon solvents. Solubilities of various ethers in perfluorocarbons and miscibility temperatures were determined. These properties were found to be greatly dependent on the polarity but also size and shape of the ether molecule. Theoretical calculations of the miscibility temperatures of organic solvents and perfluorocarbons using COSMO-RS method were correlated with experimental data. Considering the difficulties in the accurate description of the macroscopic properties, such as miscibility temperatures, from the first principles, the agreement between experimental and theoretical data is reasonable.
Reaction network of aldehyde hydrogenation over sulfided Ni-Mo/Al 2O3 catalysts
Wang, Xueqin,Saleh, Ramzi Y.,Ozkan, Umit S.
, p. 20 - 32 (2007/10/03)
A reaction network of aldehyde hydrogenation over NiMoS/Al 2O3 catalysts was studied with aldehydes with straight and branched carbon chains and different chain lengths as feed materials. The reactions in the gas phase and the liquid phase were compared. The main reaction in the aldehyde hydrogenation process is the hydrogenation of the CO double bond, which takes place over the coordinatively unsaturated sites. The major side reactions are self-condensation of aldehydes and condensation of aldehydes with alcohols. Both reactions involve α-hydrogen and are primarily catalyzed by acid-base bifunctional sites over the exposed Al2O 3 surfaces.
METHOD FOR THE PRODUCTION OF ISOPROPENYL ETHERS
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Page/Page column 14, (2010/02/13)
The invention relates to a method for the production of isopropenyl ethers of formula (A), wherein R represents an aliphatic, cycloaliphatic, aralyphatic, aromatic or heterocyclic radical which can include other substituents which do not react with acetylenes or allens, by reacting a gaseous flow (I), containing MAPD which is obtained from an olefin system and which is used to separate C3-sections, with at least one gaseous flow selected from a gaseous flow (II) containing an acetone ketal of formula (B), wherein R has the above-mentioned meaning, and a gaseous flow (III) containing a monohydroxyalcohol ROH, wherein R has the above-mentioned meaning, in the presence of a heterogeneous catalyst.
Trends in alkyl substituent effects on nucleophilic reactions of carbonyl compounds: Gas phase reactions between ammonia and R1R2COCH3+ oxonium ions
Bache-Andreassen, Lihn,Uggerud, Einar
, p. 705 - 713 (2007/10/03)
The reactivity of carbonyl substituted methyl oxonium ions (R1R2COCH3-) towards ammonia has been investigated using an FT-ICR mass spectrometer and ab initio calculations. The monosubstituted ions (R1=H: R2 = H, CH3, C2H5 and i-C3H7) show different reaction patterns with variable degree of: (1) nucleophilic substitution, (2) addition elimination and (3) proton transfer, when reacted with ammonia. In all cases addition-elimination dominates over nucleophilic substitution, and the observed reactions are slow. The trends in reactivity are consistent with the alkyl group's electronic properties, as expressed by a single parameter linear or slightly non-linear model.
Transformation of vinyloxirane on Pt-SiO2 and Pd-SiO2
Bartok, Mihaly,Fasi, Andras,Notheisz, Ferenc
, p. 40 - 47 (2007/10/03)
The transformation of vinyloxirane and ethyloxirane were studied on Pt-SiO2 and Pd-SiO2 catalysts at 273 and 301 K in a recirculation reactor, in the presence of hydrogen or deuterium. There are significant differences, not only in reaction rates, but also in reaction routes, depending upon the nature of the metal. The main reaction routes are: deoxygenation and hydrogen or deuterium addition on Pt-SiO2; isomerization and hydrogenolysis on Pd-SiO2. The reaction routes leading to the formation of the individual products are interpreted on the basis of the experimental results. In the case of the hydrogenolysis of oxiranes, Pd was shown to exhibit a special reactivity, unlike earlier observations described in the literature.
