摘要:
The invention relates to the production and purification of salts of 6,8-bis(amidiniumthio) octanoic acid, its enantiomers (+)-6,8-bis(amidiniumthio)octanoic acid and (-)-6,8-bis (amidiniumthio)octanoic acid and of the esters of these compounds as well as to their use to produce dihydrolipoic acid and .alpha.-lipoic acid.
摘要:
A process is described for the simultaneous production of 1,2- and 1,3-propanediol from glycerol. The process involves the reaction stages (a) dehydration of glycerol by feeding a gaseous glycerol-water mixture with 10 to 40 wt % glycerol at 250.degree. to 340.degree. C. over a solid catalyst with an H.sub.0 value (Hammett acidity function) of less than 2, preferably between -3 and -8.2, (b) hydration of the acrolein contained in the reaction mixture of stage (a), and (c) catalytic hydrogenation of the reaction mixture, containing 3-hydroxypropionaldehyde and hydroxyacetone, of stage (b). Two valuable products, namely 1,2- and 1,3-propanediol, can be obtained simultaneously and in high total yield from glycerol in a simple process.
摘要:
The invention relates to the preparation of optically active salts of the general formula ##STR1## from which the corresponding optically active 3-chloro-2-hydroxypropyltrimethyl ammonium chloride can be obtained by treatment with mineral acid.The L(-) form of this compound is a valuable component for the synthesis of L(-) carnitine.
摘要:
To produce thiosemicarbazide hydrazine is reacted with hydrogen cyanide and sulfur to form hydrazine thiocyanate, and this is then converted into the thiosemicarbazide at an elevated temperature. Advantageously, the reaction is carried out in a polar solvent.
摘要:
The invention relates to the production and purification of salts of 6,8-bis (amidiniumthio)octanoic acid, its enantiomers (+)-6,8-bis(amidiniumthio)octanoic acid and (-)-6,8-bis (amidiniumthio)octanoic acid and of the esters of these compounds as well as to their use to produce dihydrolipoic acid and .alpha.-lipoic acid.
摘要:
A process for the production of acrolein by dehydration of glycerol in the liquid phase or in the gaseous phase, in each case on acidic solid catalysts, is described. Compared with previously known processes, the space-time yield and catalyst service life may be surprisingly increased with higher selectivity by treating a glycerol-water mixture with a glycerol content of 10 to 40 wt. % at 180.degree. to 340.degree. C. (liquid phase) or at 250.degree. to 340.degree. C. (gaseous phase) on a solid catalyst with an H.sub.o value (Hammett acidity function) of less than +2, preferably less than -3.
摘要:
Synthesis of L-carnitine by chemical optical resolution of D,L-carnitine nitrile salts, where the D,L-carnitine nitrile salt is reacted with optically active N-acetylproline as the resolving agent in order to form the diastereomer salts after conversion to the hydroxide form, one of the two diastereomer salts is separated by fractional crystallization and the fraction containing mainly L-carnitine nitrile salt is treated with an optically inactive strong acid in order to split off the optically active N-acetylproline and then the resolving agent is separated and the resulting L-carnitine nitrile salt is saponified to L-carnitine. N-acetyl-L-proline is used as the resolving agent and the diastereomer (LL) salt is obtained in crystalline form in a high optical purity by fractional crystallization and the L-carnitine nitrile salt obtained after splitting off and separating N-acetyl-L-proline is used directly for saponification without further crystallization.
摘要:
2-Amino-5-mercapto-1,3,4-thiadiazoles can be produced in very high yields from thiosemicarbazides and carbon disulfide in aqueous phase by working in the presence of the corresponding ammonium salt of bis-2,5-mercapto-1,3,4-thiadiazole at a temperature above 40.degree. C. Preferably the process is carried out in the presence of the mother liquor from a previous reaction.
摘要:
There is provided a process for the production of .beta.-mercaptopropionic acid and its esters and nitriles by reacting the corresponding acrylic acid derivatives with trithiocarbonates in aqueous solution.