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Alkylation

About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.


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Journal ArticleDOI
TL;DR: In this paper, it was shown that carbonyl oxides formed in the gas-phase ozonolysis of alkylated alkenes are an important source of OH radicals.
Abstract: Kinetic measurements as well as B3LYP/ and MP2/6-31G(d,p) calculations provide evidence that carbonyl oxides formed in the gas-phase ozonolysis of alkylated alkenes are an important source of OH radicals. In the gas-phase ozonolysis of propene, cis-2-butene, trans-2-butene, tetramethylethene, and isoprene, 18, 17, 24, 36, and 19% OH radicals (relative to reacted ozone, error margin ≤4%) are measured using CO as a scavenger for OH. The quantum chemical calculations show that OH radical production depends on syn positioned methyl (alkyl) groups and their interaction with the terminal O atom of a carbonyl oxide. For example, in the gas-phase ozonolysis of ethene only 5% OH radicals are measured while for a carbonyl oxide with syn-positioned methyl (alkyl) group, a much larger amount of OH radicals is formed. This is due to the fact that 1,4 H migration and the formation of an intermediate hydroperoxy alkene, that is prone to undergo OO bond cleavage, is energetically more favorable than isomerization to diox...

168 citations

Journal ArticleDOI
TL;DR: A new challenging strategy for the asymmetric intermolecular enamine-catalyzed formal a-alkylation of aldehydes is reported, founded upon the use of a reagent 1 (Scheme 1), which, because of the presence of the Canizzaro or Tischenko reactions, is considered valuable.
Abstract: Catalysis with chiral secondary amines (asymmetric aminocatalysis) has become a well-established and powerful synthetic tool for modern synthetic chemistry. The impressive level of scientific competition and high quality research generated in this area have opened up new synthetic opportunities that were considered inaccessible only a few years ago. Even reactions that had been considered impossible became a reality through aminocatalysis. One of the best validations of this approach is the development of the catalytic, asymmetric direct a-alkylation of aldehydes. This highly challenging and valuable C C bond-forming strategy was completely unknown before the advent of asymmetric aminocatalysis. In 2004, Vignola and List presented the first catalytic asymmetric intramolecular a-alkylation of haloaldehydes under enamine catalysis. They demonstrated the ability of proline-derived catalysts to overcome the classical drawbacks associated with the stoichiometric alkylation of preformed aldehyde enolates, such as the tendency toward aldol condensation and the Canizzaro or Tischenko reactions. However, extension of their aminocatalytic strategy to an intermolecular version failed because of deactivation of the amine catalyst by N-alkylation with the alkyl halide. Thus, chemists started to search for different aminocatalytic strategies to accomplish the challenging goal of an intermolecular formal aldehyde a-alkylation. In 2006, Ibrahem and C2rdova reported a non-asymmetric catalytic intermolecular a-allylic alkylation of aldehydes by combination of transition-metal and enamine catalysis. More recently, MacMillan and co-workers exploited a new aminocatalytic activation concept, based on radical intermediates, to solve the synthetic problems of the catalytic asymmetric aallylation, arylation, enolation, and vinylation of unmodified aldehydes. Herein, we report a new challenging strategy for the asymmetric intermolecular enamine-catalyzed formal a-alkylation of aldehydes. The novel approach is founded upon the use of a reagent 1 (Scheme 1), which, because of the presence

168 citations

Journal ArticleDOI
TL;DR: This work details the development of ruthenium(II) catalysts for the enantioselective alkylation of chiral racemic secondary phosphines through the intermediacy of nucleophilic phosphido species, which have low barriers to pyramidal inversion.
Abstract: This work details the development of ruthenium(II) catalysts for the enantioselective alkylation of chiral racemic secondary phosphines. The reactions proceed through the intermediacy of nucleophilic phosphido species, which have low barriers to pyramidal inversion; this allows for a dynamic kinetic asymmetric alkylation. The initially discovered [((R)-iPr-PHOX)2Ru(H)][BPh4] (6) catalyst was found to be effective in the reaction with benzylic chlorides; moreover, the alkylation displayed an unusual temperature dependence. However, the limited scope of alkylation of 6 motivated further studies which led to the development of two complementary chiral mixed ligand Ru(II) catalysts of type [L1L2Ru(H)]+. These catalysts were derived from a combination of one chiral and one achiral ligand, where a synergistic interaction of the two ligands creates an effective asymmetric environment around the ruthenium center. The (R)-MeO-BiPHEP/dmpe (dmpe = 1,2-bis(dimethylphosphino)ethane) catalyst (10) was found to be effec...

167 citations

Patent
20 Oct 2006
TL;DR: In this article, a method for producing alkylated hydrocarbons is described, in which formation fluid is produced from a subsurface in situ heat treatment process and a liquid stream and a first gas stream are separated to produce at least a second gas stream.
Abstract: A method for producing alkylated hydrocarbons is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce at least a second gas stream including hydrocarbons having a carbon number of at least 3. The first gas stream and the second gas stream are introduced into an alkylation unit to produce alkylated hydrocarbons. At least a portion of the olefins in the first gas stream enhance alkylation.

167 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023652
20221,161
2021561
2020516
2019630
2018631