Mechanism of the Reaction between Benzylmagnesium Chloride and Carbonyl Compounds. A Detailed Study with Formaldehyde

Robert A. Benkeser, Dudley Clark Snyder

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The reaction of benzylmagnesium chloride in THF with monomeric formaldehyde has been studied in detail. A mechanism is presented which accounts for the formation of the products, 2-phenylethanol, o-tolylcarbinol, and o-(2-hydroxyethyl)benzyl alcohol. A change in technique for Grignard titration and formaldehyde addition results in a much-improved mass balance than achieved previously. The decreased yield of the major product, o-tolylcarbinol, with increased reaction time is explained in terms of a hitherto unsuspected equilibrium influenced by tbe polymerization of monomeric formaldehyde. An intermediate organometallic species which could lead to some of the diol product, o-(2-hydroxyethyl)benzyl alcohol can be trapped as the trimethylsilyl derivative, but the quantity is insufficient to account for the amount of diol when an excess of formaldehyde is employed. An ene or Prins reaction is invoked for the formation of most of the diol. Deuterium tracer studies suggest competition between a proton abstraction pathway leading to the trimethylsilyl-trapped organometallic species and a base-catalyzed, stereospecific 1,3 hydrogen shift.

Original languageEnglish (US)
Pages (from-to)1243-1249
Number of pages7
JournalJournal of Organic Chemistry
Volume47
Issue number7
DOIs
StatePublished - Jan 1 1982

Fingerprint

Carbonyl compounds
Formaldehyde
Chlorides
Benzyl Alcohol
Organometallics
Phenylethyl Alcohol
Deuterium
Titration
Protons
Hydrogen
Polymerization
Derivatives

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Cite this

@article{d88447869750452f881003df2d49664e,
title = "Mechanism of the Reaction between Benzylmagnesium Chloride and Carbonyl Compounds. A Detailed Study with Formaldehyde",
abstract = "The reaction of benzylmagnesium chloride in THF with monomeric formaldehyde has been studied in detail. A mechanism is presented which accounts for the formation of the products, 2-phenylethanol, o-tolylcarbinol, and o-(2-hydroxyethyl)benzyl alcohol. A change in technique for Grignard titration and formaldehyde addition results in a much-improved mass balance than achieved previously. The decreased yield of the major product, o-tolylcarbinol, with increased reaction time is explained in terms of a hitherto unsuspected equilibrium influenced by tbe polymerization of monomeric formaldehyde. An intermediate organometallic species which could lead to some of the diol product, o-(2-hydroxyethyl)benzyl alcohol can be trapped as the trimethylsilyl derivative, but the quantity is insufficient to account for the amount of diol when an excess of formaldehyde is employed. An ene or Prins reaction is invoked for the formation of most of the diol. Deuterium tracer studies suggest competition between a proton abstraction pathway leading to the trimethylsilyl-trapped organometallic species and a base-catalyzed, stereospecific 1,3 hydrogen shift.",
author = "Benkeser, {Robert A.} and Snyder, {Dudley Clark}",
year = "1982",
month = "1",
day = "1",
doi = "10.1021/jo00346a020",
language = "English (US)",
volume = "47",
pages = "1243--1249",
journal = "Journal of Organic Chemistry",
issn = "0022-3263",
publisher = "American Chemical Society",
number = "7",

}

Mechanism of the Reaction between Benzylmagnesium Chloride and Carbonyl Compounds. A Detailed Study with Formaldehyde. / Benkeser, Robert A.; Snyder, Dudley Clark.

In: Journal of Organic Chemistry, Vol. 47, No. 7, 01.01.1982, p. 1243-1249.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Mechanism of the Reaction between Benzylmagnesium Chloride and Carbonyl Compounds. A Detailed Study with Formaldehyde

AU - Benkeser, Robert A.

AU - Snyder, Dudley Clark

PY - 1982/1/1

Y1 - 1982/1/1

N2 - The reaction of benzylmagnesium chloride in THF with monomeric formaldehyde has been studied in detail. A mechanism is presented which accounts for the formation of the products, 2-phenylethanol, o-tolylcarbinol, and o-(2-hydroxyethyl)benzyl alcohol. A change in technique for Grignard titration and formaldehyde addition results in a much-improved mass balance than achieved previously. The decreased yield of the major product, o-tolylcarbinol, with increased reaction time is explained in terms of a hitherto unsuspected equilibrium influenced by tbe polymerization of monomeric formaldehyde. An intermediate organometallic species which could lead to some of the diol product, o-(2-hydroxyethyl)benzyl alcohol can be trapped as the trimethylsilyl derivative, but the quantity is insufficient to account for the amount of diol when an excess of formaldehyde is employed. An ene or Prins reaction is invoked for the formation of most of the diol. Deuterium tracer studies suggest competition between a proton abstraction pathway leading to the trimethylsilyl-trapped organometallic species and a base-catalyzed, stereospecific 1,3 hydrogen shift.

AB - The reaction of benzylmagnesium chloride in THF with monomeric formaldehyde has been studied in detail. A mechanism is presented which accounts for the formation of the products, 2-phenylethanol, o-tolylcarbinol, and o-(2-hydroxyethyl)benzyl alcohol. A change in technique for Grignard titration and formaldehyde addition results in a much-improved mass balance than achieved previously. The decreased yield of the major product, o-tolylcarbinol, with increased reaction time is explained in terms of a hitherto unsuspected equilibrium influenced by tbe polymerization of monomeric formaldehyde. An intermediate organometallic species which could lead to some of the diol product, o-(2-hydroxyethyl)benzyl alcohol can be trapped as the trimethylsilyl derivative, but the quantity is insufficient to account for the amount of diol when an excess of formaldehyde is employed. An ene or Prins reaction is invoked for the formation of most of the diol. Deuterium tracer studies suggest competition between a proton abstraction pathway leading to the trimethylsilyl-trapped organometallic species and a base-catalyzed, stereospecific 1,3 hydrogen shift.

UR - http://www.scopus.com/inward/record.url?scp=0000138959&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000138959&partnerID=8YFLogxK

U2 - 10.1021/jo00346a020

DO - 10.1021/jo00346a020

M3 - Article

AN - SCOPUS:0000138959

VL - 47

SP - 1243

EP - 1249

JO - Journal of Organic Chemistry

JF - Journal of Organic Chemistry

SN - 0022-3263

IS - 7

ER -