摘要:
A crystalline L-alpha-aspartyl-L-phenyl-alanine methyl ester product is disclosed. The product is obtained by crystallizing the ester from an aqueous solution, by cooling. The initial concentration of ester in the aqueous solution used provides at least 10 grams of precipitated solid phase per liter of solution. The solution is cooled through conductive heat transfer without effecting forced flow to form a sherbet-like pseudo solid phase.
摘要:
A method for dissolving crystalline L-alpha-aspartyl-L-phenyl-alanine methyl ester product is disclosed. The product is obtained by crystallizing the ester from an aqueous solution, by cooling. The initial concentration of ester in the aqueous solution used provides at least 10 grams of precipitated solid phase per liter of solution. The solution is cooled through conductive heat transfer without effecting forced flow to form a sherbet-like pseudo solid phase.
摘要:
In crystallizing .alpha.-APM from a water solution or a mixed solvent solution of water and a lower alcohol in a crystallizer, the pressure in the crystallizer is held at not higher than atmospheric pressure, a water or water/alcohol mixed solution of .alpha.-APM is fed into the crystallizer with stirring so that the solvent is vaporized, and the crystallization solution is cooled and crystallized by the latent heat of vaporization or is heated so as to prevent supercooling.
摘要:
A method of preparing .varies.-L-aspartyl-L-phenylalanine methyl ester hydrochloride (.varies.-APM.HCL) from a reaction mixture of N-formyl-L-aspartic acid anhydride and L-phenylalanine methyl ester (PM), wherein .alpha.-APM.HCl is produced without isolating an intermediate by solid-liquid separation during the course of the reaction process.
摘要:
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.
摘要:
An acid addition salt of .alpha.-APM is dissolved or suspended in an aqueous medium at 50.degree. C. or lower at a pH of 3 or less and a concentration of the salt of 3 wt.% or more (solution A). A liquid having a pH of 3 or more and containing or not containing .alpha.-APM is prepared (solution B) and gradually mixed with solution A with stirring. The temperature of the liquid mixture is kept to be 40.degree. C. or lower and the pH value of the mixture is kept at 3 or more, optionally adding a base thereto, whereby crystals of .alpha.-APM are precipitated out.
摘要:
A process for crystallizing L-alpha-aspartyl-L-phenylalanine methyl ester from its aqueous solution by cooling, which comprises adjusting the initial concentration of the ester so that the amount of a precipitated solid phase to be formed after cooling becomes about 10 grams or more per liter of the solvent, cooling the solution through conductive heat transfer through a cooled surface to form an apparently sherbet-like pseudosolid phase without causing forced flow by mechanical stirring or the like, and optionally further cooling the system after formation of the pseudosolid phase, is disclosed along with various apparatuses which may be used to carry out the invention.
摘要:
An autonomous continuous analysis method and apparatus using Dip and Read type analytical implements. A series of operations of taking out analytical implements, dipping them in the sample solution, optical measurement, calculation, and disposal of the used sample solution are performed automatically.The dip stage, in particular, is automated by use of an analytical-implement automatic supply device and an analytical implement automatic handling device which, holding an analytical implement, dips it in the sample solution, and sets it ona reaction turntable. A number of analytical implements are put in a storage section comprising a bottom section provided with an analytical implement groove and at least one inside surface which is parallel with the groove, are taken out one by one by the relative movement of the groove and in normal and reverse direction and by stopping in a specified position after confirming by a detector that an implement has been caught in the groove.
摘要:
A process for producing N-formyl-aspartylphenylalanine or its methyl ester, wherein aspartic acid is reacted with formic acid and acetic anhydride in approximately stoichiometric quantities in the presence or absence of a catalyst and phenylalanine or its methyl ester is directly added to the dehydration mixture. This process has a higher yield of the desired N-formyl-dipeptide and minimizes the amount of by-products and unreacted starting materials.
摘要:
A method for optical resolution of a DL-amino acid comprising reacting the DL-amino acid with an optically active N-acyl aspartic acid in a solvent or mixture of solvents, and separating the resulting two diasteromeric salts by way of the difference between their solubilities in the solvent or mixture of solvents. The difference in solubility may be enhanced by cooling, concentration, addition of a solubility-decreasing organic solvent, pH adjustment or salting out.