Abstract: L-ascorbic acid is produced by allowing an acid to act on 2-keto-L-gulonic acid in a mixture solvent of an inert organic solvent and an aliphatic ketone in the presence of water and a surfactant.The method produces L-ascorbic acid in a high yield 90% or more and is an industrially advantageous method.

Abstract: The present specification relates to an industrially advantageous process for producing vitamin A derivatives which are useful as medicaments, feed additives, food additives and the like. The process provides vitamin A derivatives, particularly all-trans vitamin A derivatives in high yield and purity.

Abstract: There are disclosed a compound of the general formula (I): ##STR1## wherein the group R--CO-- is an acyl group and its production. There is also disclosed a process for producing optically active (.+-.)-(3a.alpha., 4.alpha., 6a.alpha.)-tetrahydro-4-acetoxy-1,3-dibenzyl-1H-thieno[3,4-d]imidazol-2(3H )-one by using the compound (I). The compound (I) can be used as an intermediate for producing D-biotin which is useful as medicaments and feed additives for animals.

Abstract: 6-O-(2-keto-L-gulonoyl)-L-ascorbate substantially free from 2-keto-L-gulonic acid is produced by allowing an acid to act on 2-keto-L-gulonic acid in an inert organic solvent and recovering 6-O-(2-keto-L-gulonoyl)-L-ascorbate from the reaction mixture.6-O-(2-keto-L-gulonoyl)-L-ascorbate is more fat-soluble than L-ascorbic acid and is expected of the use as a prodrug for L-ascorbic acid that can be absorbed from the intestinal tract.

Abstract: A novel 2-lower alkyl-4-amino-5-substituted iminopyrimidine compound represented by the formula: ##STR1## wherein R is a lower alkyl, and Y is hydroxyl or amino which may be protected or a salt thereof is obtainable by allowing a formylpyrimidine compound represented by the formula: ##STR2## wherein R is a lower alkyl to react with a compound represented by the formula H.sub.2 N--Y, wherein Y is hydroxyl or amino which may be protected, or a salts thereof. The iminopyrimidine compound gives the known pyrimidine compound represented by the formula: ##STR3## wherein R is as defined above in high yield. Therefor, the process is very useful as an industrial production method.

Abstract: A compound of the formula: ##STR1## wherein R is 2-methylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, n-pentyl, an alkyl group of 6 or 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms, or a pharmaceutically acceptable salt thereof and processes for preparing the same are provided. The compound can orally be applied as antibiotics having improved absorbability.

Abstract: A novel aminothiazoleacetic acid derivative which is an advantageous synthetic intermediate for .beta.-lactam antibiotics, and its production method and use. Starting with diketene, the production method comprises the following squence of steps. ##STR1## (In the above formulas, R is lower alkyl or phenyl; R.sub.1 and R.sub.2 each are hydrogen or lower alkyl; X and X' each are halogen; W is S or SO.sub.

Abstract: Crystallized cephalosporin salts, particularly crystalline addition salt of pivaloyloxymethyl 7.beta.-[2-(2-aminothiazol-4-yl)acetamido]-3-[[[1-(2-dimethylaminoethyl)-1 H-tetrazol-5-yl]thio]methyl]ceph-3-em-4-carboxylate with hydrochloric acid, tartaric acid or citric acid, which is very stable and is readily adsorbable through intestinal tract, with little individual differences, when the salt is applied orally.