Esterification Manufacture of Malonic Ester

Ross, Auburn A.; Bibbins, F.E.

doi:10.1021/ie50336a006

Cited by 3 publications

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Malonic Ester Synthesis

2010

Comprehensive Organic Name Reactions and Reagents

View full text Add to dashboard Cite

It is a common reaction using dialkyl malonates, mostly diethyl malonate, as starting material, and is known as malonic ester synthesis. The reaction mechanism shows that the reaction proceeds via the participation of the α‐methylene protons of dialkyl malonates, which usually undergo nucleophilic substitutions and nucleophilic additions. It has been found that the alkylation rate is related to the acidity of α‐proton. During the alkylation of malonic acid ester, the reversible cleavage of formed alkyl malonic acid ester or dialkyl malonic acid ester gives a simple alkyl ester. These alkylated malonic acid esters are used to synthesize barbiturates. The reaction has been modified for traceless synthesis on solid support and after the desired reaction, one of the ester groups can be removed. This reaction has been found useful in organic synthesis.

show abstract

Malonic Ester Synthesis

2010

Comprehensive Organic Name Reactions and Reagents

View full text Add to dashboard Cite

show abstract

The production of DL‐methionine on a semi‐technical and pilot scale

Hands¹,

Millidge²,

Walker³

1947

J. Chem. Technol. Biotechnol.

View full text Add to dashboard Cite

Substantial quantities of DL-mcthiorinc were urgently required by the Medical Research Council in England during the latter part of the war. The Ministry of Supply undertook the development -up to a pilot scale of n process thought to be suitable for quantity production of methionine of high purity. The results of the first stages of this development, i.c., labOI'3tOry research, have already been publishcd.1 The present paper is concerned with the semitechnical and pilot scale developmentiof thc process.(i) A total of about 160 Ib. of crude methionine has been prepared, the early batches being between 5 and 11 Ib. and the largest batch yielding 79 Ib. The total quantiv of recrystallized material produced from the whole output of crude methionine was IZI Ib. (recrystallization was carried out partly in lab-scale glass equipment and partly in enamelled equipment).(ii) The process appears to be quite adaptable to large scale application but further work is required in order to establish optimum working conditions, particularly as regards the preparation of methyl F-chlorethyl sulphide.(iii) An ideal representation of the sequence of rcacuons leading to methionine is eiven in Fig. I. FiK. z is a mass flowsheet showing estimatedquantities Tor the production of a 100 Ib. batch of crude methionine. . The yields on which this flowsheet was drawn up are those obtained during the production of smaller (5-11 Ib.) batches of methionine and the yields obtained in practice during production of the larger batches (of which only two were made) were in some stages appreciably higher and in other stages appreciably lower than those shown in Fig. 2. Nevertheless we consider that the figures given in Fig. z are a conservative indication of what could be realized during production of batches of t-his size after more experimental work has been carried out on the lines suggested in this paper.(iv) We estimate that the cost of specification methionine prepared by this process (based on actual quantities of materials and labour used to prepare the larger batches) was about one shilling per gram. The only quoted price of which we are aware is that given in a 1939 catalogue in which a figure of 8s. 6d. per gram is quoted. General discussion of the reactions involvedDiethy! jna1onate.-Work on the preparation of this compound was started only when supplies of the ester became difficult due to war conditions ; later the situation eased and further work was abandoned before the process had been fully developed to large scale operation. As this compound is prepared by published methods and is normally readily obtainable, no further mention of it will be made. In passing it may be added that the crude carbon tetrachloride extract of the ester (92% ester on solvent free basis) was found to brominate readily both at 6 0 ' and at room temperature. This point may have a bearing on the cost of diethyl bromomalonatc in future work.Diefllyl brorrrorrialoriafe.-This compound was prepared in an overall yield of 72-77"/0 distilled product without difficu...

show abstract