摘要:
A process for preparing 9-(Z)-retinoic acid from mother liquors from the industrial preparation of C.sub.15 -triarylphosphonium salts of the general formula I ##STR1## where R.sup.1 to R.sup.3 are each aryl and X.sup..crclbar. is halogen or (HSO.sub.4).sup..crclbar., in an organic solvent, which comprisesA. increasing the proportion of 9-(Z)-C.sub.15 -triarylphosphonium salt in the C.sub.15 -triarylphosphonium salts isolated from the mother liquor by treatment with isopropanol at elevated temperature, cooling and separating off the all-(E)-C.sub.15 -triarylphosphonium salt which has crystallized out,B. subjecting the resulting C.sub.15 -triarylphosphonium salt to a Wittig reaction with an alkyl .beta.-formylcrotonate of the general formula ##STR2## and C. hydrolyzing the resulting oily retinoic ester mixture in a C.sub.3 -C.sub.9 -alkanol, preferably in a propanol or butanol, precipitating the resulting 9-(Z)-retinoic acid where appropriate by adding methanol as crystals, with all-(E)-retinoic acid and other retinoic acid isomers remaining in the alkanolic solution.
摘要:
13-(Z)-Retinoic acid is prepared bya) reacting 5-hydroxy-4-methyl-2(5H)-furanone with a [3-methyl-5-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4-pentadienyl]triarylphosphonium salt andb) subsequently partially isomerizing the resulting mixture of 13-(Z)- and 11,13-di-(Z)-retinoic acid,where the reaction in step a) is carried out in the presence of lithium hydroxide as alkali metal hydroxide and in dimethylformamide as solvent at from +10.degree. to -9.degree. C. and/or the isomerization in step b) is carried out by irradiating the mixture of isomers obtained in a) in an organic solvent in the presence of a photosensitizer with light in the wavelength range from 200 to 600 nm.
摘要:
A process for preparing folic acid, which comprises reacting a tetraalkoxypropanol of the general formula I, in which the substituents R are C1-C4-alkyl, with triaminopyrimidone of the formula II and p-aminobenzoyl-L-glutamic acid of the formula III
摘要:
.beta.-Carotene products with a high proportion of the 9(Z) isomer are prepared starting from mother liquors from the industrial preparation of .beta.-ionylideneethyltriarylphosphonium salts (C.sub.15 -triarylphosphonium salts) by Wittig reaction of a C.sub.15 -triarylphosphonium salt which has been enriched in the 9Z isomer directly with .beta.-apo-12'-carotenal or else with 2,7-dimethyl-2,4,6-octatrienedial and subsequently with the C.sub.15 -triarylphosphonium salt and subsequent thermal isomerization.
摘要:
A process for preparing 4-hydroxy-1,2,2-trimethylcyclopentyl methyl ketones of the general formula I, in particular of the (1R,4S)-4-hydroxy-1,2,2-trimethylcyclopentyl methyl ketone of the formula Ia ##STR1## which is required for preparing the red dye capsorubin which is in demand, starts from 2,2,6-trimethylcyclohexanones of the general formula II ##STR2## where R is hydrogen or a protective group, via the novel intermediates of the general formulae V and VI ##STR3## by diastereoselective epoxidation and reaction of the resulting 7-oxabicyclo[4.1.0]heptanes of the general formula VIII ##STR4## with Lewis acids and, where appropriate, removal of the protective group. Also claimed are the novel intermediates of the formula V and their (1S) and (1R) isomers and those of the formula VIII as well as their (1R,3S,6S), (1S,3S,6R) and (1R,3R,6S) isomers.
摘要:
5-Hydroxy-4-methyl-2(5H)-furanone is prepared by cyclization of alkyl .beta.-formylcrotonates by heating with dilute aqueous hydrochloric acid or, advantageously, in the presence of dilute aqueous hydrochloric acid and catalytic amounts of methanol as solubilizer, subsequent workup of the reaction mixture by distillation and, where appropriate, isomerization of the 5-methoxy- or 5-ethoxy-4-methyl-2(5H)-furanone, which is formed as byproduct, by heating with dilute hydrochloric acid.
摘要:
Improved process for the preparation of astaxanthin by Wittig reaction of 2 mol of 3-methyl-5-(2,6,6-trimethyl-3-oxo-4-hydroxy-1-cyclohexenyl)-2,4-pentadienyltriarylphosphonium salts with one mol of 2,7-dimethyl-2,4,6-octatrienedial avoiding the use of halohydrocarbons as solvents.