摘要:
A process for the preparation of &bgr;,&ggr;,&dgr;-unsaturated ketones and/or &agr;,&bgr;,&ggr;,&dgr;-unsaturated ketones by the reaction of an unsaturated alcohol with an enol ether or mixture of enol ethers, with formation of ketals as a by-product, at temperatures of from 50° C. to 200° C., in the presence of an acid catalyst, whereby one or all of the reagents is/are heated to the reaction temperature of from 50° C. to 200° C. before the acid catalyst is added.
摘要:
A process for preparing trimethylhydroquinone diacetate, with subsequent hydrolysis to give trimethylhydroquinone, the process including reacting 2,2,6-trimethylcyclohexane-1,4-dione under oxidative conditions, in the presence of a sulfonating agent and a strong acid, and in the presence of an acylating agent.
摘要:
A process for the preparation of nicotinic acid by the direct oxidation of &bgr;-picoline in the gas phase, wherein water and &bgr;-picoline are fed separately to the catalyst bed and the catalyst is based on a titanium dioxide support which has been prepared by the sulfate method and has a high specific surface area and a vanadium oxide content of from 5 to 50 %.
摘要:
Process for the selective preparation of &bgr;-isophorone epoxide by epoxidation of &bgr;-isophorone with organic percarboxylic acids at a water content of less than 5 wt. %.
摘要:
A process for the production of &agr;-tocopherol acetate in a recirculating process by condensation of trimethylhydroquinone and isophytol in the presence of a catalyst system of a zinc halide and an aqueous protonic acid and, optionally, an elemental metal, in a polar solvent/water mixture extractable or miscible with water, and subsequent acylation of the resultant &agr;-tocopherol and recirculation of the catalyst system.
摘要:
The invention relates to an improved process for the production of 2,3,5-trimethylhydroquinone diesters by rearrangement of 2,6,6-trimethyl-2-cyclohexene-1,4-dione (4-oxoisophorone, ketoisophorone) in the presence of a dissolved, acidic catalyst and an acylating agent, such as for example carboxylic anhydrides or carboxylic acid halides. The 2,3,5-trimethylhydroquinone diester can optionally then be saponified to give free 2,3,5-trimethylhydroquinone (TMHQ), which is a valuable building block in the synthesis of vitamin E.
摘要:
A process for the preparation of 2,3,5-trimethyl-p-benzoquinone by oxidation of 2,3,5- or 2,3,6-trimethylphenol using oxygen or a gas mixture containing oxygen in the presence of a two-phase liquid reaction medium composed of water and a neocarboxylic acid having to 11 carbon atoms with a copper (II) halide-containing catalyst system at elevated temperature.
摘要:
A process for the production of 2,3,5-trimethylhydroquinone diesters by aromatization of 2,6,6-trimethyl-2-cyclohexene-1,4-dione (4-oxoisophorone, ketoisophorone, KIP) with an acylating agent and an acidic soluble or insoluble catalyst, which process may be operated alternatively continuously or discontinuously. The process includes the following steps: a) a carboxylic anhydride having a C1 to C4 alkyl residue is used as the acylating agent, b) after the reaction, a proportion of the resultant carboxylic acid is optionally removed by distillation, c) the reaction solution is cooled, d) the product which has crystallized out is separated and washed, and e) the filtrate is returned to step a).
摘要:
The invention relates to an improved method for the production of 2,3,5-trimethylhydroquinone by rearranging 4-oxo-isophorone (keto-isophorone, 3,5,5-trimethylcyclohex-2-en[e]-1,4-dione) to a trimethylhydroquinone diester and by its subsequent saponification. ##STR1##
摘要:
Process for the preparation of unsaturated 4,5-allene ketones by reaction of tertiary propargyl alcohols with alkenyl alkyl ethers or ketals in the presence of aliphatic sulfonic acids or sulfonic acid salts.