Ajinomoto Co., Ltd.

Takehiko Kataoka

Shinichi Kishimoto

Tadashi Takemoto

Akihiko Yasaki

Harutoshi Ohura

Osahiro Sato

Toshihisa Kato

Haruo Kawasaki

Atsuhiko Hirano

Yoshinobu Uchida

Satoshi Yamahara

Makoto Nishikawa

Wet crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester with low water content can be obtained with high efficiency by solid-liquid separation of an aqueous suspension of .alpha.-L-aspartyl-L-phenylalanine methyl ester. The aqueous suspension is compressed at a final pressure of at least 20 kg/cm.sup.2 as a bearing pressure, and the wet crystals are dried after compression.

Process for producing .alpha.-L-aspartyl-L-phenylalanine methyl ester

The present invention provides an industrial method of producing N-formyl-L-aspartic anhydride from N-formyl-L-aspartic acid, formic acid and acetic anhydride with less residual formic acid than conventional methods.

Method of preparing N-formyl-L-aspartic anhydride

A process for quickly and reproducibly obtaining .alpha.-L-aspartyl-L-phenylalanine methyl ester with controlled water content is disclosed. Wet crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester obtained by crystallization are subjected to a drying step to adjust the water content to not more than 5 wt %, and subsequently a gas adjusted to a temperature of 20-80.degree. C. and relative humidity of 20-90 RH % is contacted with the dried crystals to control water content.

An industrial process for recovering L-phenylalanine in high yield from a side stream obtained from .alpha.-APM is disclosed. L-aspartic acid or an aqueous solution thereof is added to such a side stream when hydrolysis of the side stream is performed under acidic conditions with a mineral acid, the pH of the reaction mixture obtained by hydrolysis is then adjusted to 5 to 6 to precipitate L-phenylalanine.

Process for recovering L-phenylalanine

A method for the solid-liquid separation of a suspension of .alpha.-L-aspartyl-L-phenylalanine methyl ester (.alpha.-APM) or its hydrochloride salt (.alpha.-APM.HCl), wherein an aqueous suspension of .alpha.-L-aspartyl-L-phenylalanine methyl ester or its hydrochloride salt is subjected to continuous separation by vacuum filtration.

Method of preparing .alpha.-L-aspartyl-L-phenylalanine methyl ester or

In producing granules of .alpha.-L-aspartyl-L-phenylalanine methyl ester having a particle size of falling within a determined particle size range by compaction granulation, formation of fine powdery .alpha.-APM is prevented by breaking the compacted .alpha.-APM so that the one-pass yield of the granules is elevated and the sieving efficiency is elevated. In a method of preparing granules of .alpha.-L-aspartyl-L-phenylalanine methyl ester by compaction granulation of the ester singly or along with a vehicle of not more than the same amount of the ester, after the compaction or after having roughly broken the compacted material, the material is broken down so as to pass through a screen or perforated plate having pores with a diameter falling within the range of from 1 mm to 10 mm and then further broken and classified.

Method of preparing granules of dipeptide

The present invention discloses a method to separate each component from a mixed solution of organic solvents obtained during the production of .alpha.-L-aspartyl-L-phenylalanine methyl ester, which is useful as a sweetener, namely, a mixed solution of acetic acid and toluene or a mixed solution of acetic acid, toluene and formic acid, recovering each component with a high recovery ratio with as small number of operations as possible. The method rationalizes the process and is highly valuable in practical use. When each component is separated and recovered from a mixed solution containing acetic acid and toluene as the main components, acetic acid and toluene are separated by azeotropic distillation using water as an azeotropic solvent, and when each component is separated and recovered from a mixed solution containing acetic acid, toluene and formic acid as the main components, (a) the mixed solution is distilled and formic acid is recovered from the top of the column and a mixed solution of acetic acid and toluene is recovered from the bottom of the column; and (b) the mixed solution obtained from the bottom is distilled by using water as an azeotropic solvent and toluene is recovered from the top of the column and acetic acid is recovered from the bottom of the column.

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Kawasaki, Japan

Takehiko Kataoka