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Mechanism insight into the cyanide-catalyzed benzoin condensation: a density functional theory study.

06:00 EDT 28th August 2010 | BioPortfolio

Summary of "Mechanism insight into the cyanide-catalyzed benzoin condensation: a density functional theory study."

The reaction mechanism of the cyanide-catalyzed benzoin condensation without protonic solvent assistance has been studied computationally for the first time employing the density functional theory (B3LYP) method in conjunction with 6-31+G(d,p) basis set. Four possible pathways have been investigated. A new proposed pathway on the basis of the Lapworth mechanism is determined to be the dominant pathway in aprotic solvent, in which the formation of the Lapworth's cyanohydrin intermediate is a sequence including three steps assisted by benzaldehyde, clearly manifesting that the reaction can take place in aprotic solvents such as DMSO. In this favorable pathway with six possible transition states located along the potential energy surface, the reaction of the cyanide/benzaldehyde complex with another benzaldehyde to afford an alpha-hydroxy ether is the rate-determining dynamically with the activation free energy barrier of 26.9 kcal/mol, and the step to form cyanohydrin intermediate from alpha-hydroxy ether is partially rate-determining for its relatively significant barrier 20.0 kcal/mol.

Affiliation

College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education and State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610064, People's Republic of China.

Journal Details

This article was published in the following journal.

Name: The journal of physical chemistry. A
ISSN: 1520-5215
Pages: 9222-30

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Medical and Biotech [MESH] Definitions

A white crystalline compound prepared by condensation of benzaldehyde in potassium cyanide and used in organic syntheses. This should not be confused with benzoin gum from STYRAX.

A plant genus in the LAURACEAE family. Lindera benzoin is a source of a balsamic resin called benzoin which is up to 1/3 BENZOIC ACID. This should not be confused with the chemical BENZOIN or the plant STYRAX BENZOIDES.

Hydrogen cyanide (HCN); A toxic liquid or colorless gas. It is found in the smoke of various tobacco products and released by combustion of nitrogen-containing organic materials.

Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.

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