PREPARATION OF C14-LABELLED ACIDS FROM C14O2 AND ARYL LITHIUM COMPOUNDS

1959 ◽  
Vol 37 (1) ◽  
pp. 1439-1446
Author(s):  
A. C. Neish
Keyword(s):  
Benzoic Acid ◽  
Barium Carbonate ◽  
Grignard Reagents ◽  
Similar Sequence ◽  
Butyl Lithium ◽  
Organolithium Compounds ◽  
Lithium Compounds

A simplified technique was developed for carbonation of Grignard reagents or organolithium compounds, with C14O2 generated from barium carbonate. 3,4-(Dibenzyloxy)-bromobenzene was treated with n-butyl lithium in ether and then with C14O2 to give 3,4-(dibenzyloxy)-benzoic acid-carboxyl-C14. The yield was 74% based on barium carbonate. 2,6-Dichlorobenzoic acid-carboxyl-C14 (yield 77%) and 3,5-dichlorobenzoic acid-carboxyl-C14 (yield 76%) were prepared from the corresponding dichlorobromobenzenes by a similar sequence of reactions. Attempts to synthesize 2,4- and 2,5-dichlorobenzoic acids by this route gave poor yields of unidentified acids, from which the expected products could not be isolated.

PREPARATION OF C14-LABELLED ACIDS FROM C14O2 AND ARYL LITHIUM COMPOUNDS

1959 ◽  
Vol 37 (12) ◽  
pp. 1439-1446 ◽  
Author(s):  
A. C. Neish
Keyword(s):  
Benzoic Acid ◽  
Barium Carbonate ◽  
Grignard Reagents ◽  
Similar Sequence ◽  
Butyl Lithium ◽  
Organolithium Compounds ◽  
Lithium Compounds

A simplified technique was developed for carbonation of Grignard reagents or organolithium compounds, with C14O2 generated from barium carbonate. 3,4-(Dibenzyloxy)-bromobenzene was treated with n-butyl lithium in ether and then with C14O2 to give 3,4-(dibenzyloxy)-benzoic acid-carboxyl-C14. The yield was 74% based on barium carbonate. 2,6-Dichlorobenzoic acid-carboxyl-C14 (yield 77%) and 3,5-dichlorobenzoic acid-carboxyl-C14 (yield 76%) were prepared from the corresponding dichlorobromobenzenes by a similar sequence of reactions. Attempts to synthesize 2,4- and 2,5-dichlorobenzoic acids by this route gave poor yields of unidentified acids, from which the expected products could not be isolated.

STRUCTURE OF GRIGNARD REAGENTS AND ORGANOLITHIUM COMPOUNDS

1963 ◽  
pp. 767-773 ◽  
Author(s):  
Gideon Fraenkel ◽  
David G. Adams ◽  
James Williams
Keyword(s):  
Grignard Reagents ◽  
Organolithium Compounds

Reactions of organolithium compounds and Grignard reagents with lithium carboxylates

1975 ◽  
Vol 40 (12) ◽  
pp. 1770-1773 ◽  
Author(s):  
Robert Levine ◽  
Marvin J. Karten ◽  
William M. Kadunce
Keyword(s):  
Grignard Reagents ◽  
Organolithium Compounds

PREPARATION OF CAFFEIC AND DIHYDROCAFFEIC ACIDS BY METHODS SUITABLE FOR INTRODUCTION OF C14 INTO THE β-POSITION

1959 ◽  
Vol 37 (12) ◽  
pp. 1431-1438 ◽  
Author(s):  
A. C. Neish
Keyword(s):  
Acetic Acid ◽  
Benzoic Acid ◽  
Caffeic Acid ◽  
Malonic Acid ◽  
Cinnamic Acid ◽  
Catalytic Hydrogenation ◽  
Benzoyl Chloride ◽  
Protocatechuic Acid ◽  
Barium Carbonate ◽  
Hydrogen Bromide

3,4-(Dibenzyloxy)-benzoyl chloride (m.p. 95°) was prepared from the corresponding acid, and reduced to 3,4-(dibenzyloxy)-benzaldehyde (m.p. 86°) by Rosenmund's method. The over-all yield of this aldehyde was 52%, based on the barium carbonate used for preparation of the acid. The aldehyde was debenzylated by hydrogen bromide in acetic acid, and the protocatechualdehyde thus obtained was condensed with malonic acid, to give caffeic acid. Condensation of 3,4-(dibenzyloxy)-benzaldehyde with malonic acid gave 3,4–(dibenzyloxy)-cinnamic acid (m.p. 206–208°) which was converted to dihydrocaffeic acid by catalytic hydrogenation. The over-all yields of caffeic and dihydrocaffeic acids were 36% and 39%, respectively, based on barium carbonate. Protocatechuic acid was readily obtained by hydrogenolysis of 3,4-(dibenzyloxy)-benzoic acid; the yield was 70% based on carbonate.

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