摘要:
Allyl alcohols are isomerized in aqueous solution in the presence of protonic acids, with the pH of the reaction mixture being adjusted to the range from 2 to 5 with an acid concentration below 0.16 mol per liter of the reaction mixture or with a buffer which comprises the protonic acid.
摘要:
A process is described for the continuous preparation of dimethylvinylcarbinol (DMVC) by continuously reacting prenol with the aqueous solution of a protic acid in the still or in the lower part of a rectification column while distilling off the DMVC formed in the form of an azeotropic mixture with water, which comprises a) during the reaction ensuring that as far as possible no liquid two-phase mixture forms in the reaction mixture, b) distilling off the DMVC which forms at a reflux ratio of at least 2, as a result of which there is virtually no more prenol present in the distillate from the column, and c) setting the reaction volume and/or the amount of prenol added per hour and/or the concentration of protons in the reaction mixture in such a manner that the quotient, defined as residence time concentration coefficient, of the reaction volume and the volume of prenol added per hour multiplied by the concentration of protons in the reaction mixture has a value between 0.001 h·mol/l and 1 h·mol/l. In this connection, the formation of a liquid two-phase mixture in the reaction mixture is prevented, in addition to avoiding too large a prenol excess, by continuously taking from the reaction mixture a partial stream, passing it over a phase separation vessel, completely or at least largely removing there the small quantities, formed in the course of the reaction, of organic by-products which are insoluble or only partially soluble in water, and returning the aqueous phase to the reaction volume.
摘要:
A process is proposed for preparing C5 acetate for Vitamin A synthesis by hydroformylation of 3,4-diacetoxybut-1-ene (3,4-DABE), according to which a 3,4-DABE is used which is obtained by acetoxylation of 1,3-butadiene with acetic acid and air in the presence of a catalyst and removing by distillation the 3,4-DABE formed in this case as by-product.
摘要:
A process is described for preparing tetrahydrogeranylacetone in which pseudoionone, geranylacetone and/or dihydrogeranylacetone in a liquid phase, in which particles of a catalyst which is capable of preferentially hydrogenating carbon-carbon double bonds over carbon-oxygen double bonds are suspended, is conducted through a device which inhibits the transport of the catalyst particles in the presence of a hydrogen-containing gas.
摘要翻译:描述了一种制备四氢ger anyl anyl A A is ger ger ger through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through 在含氢气体的存在下抑制催化剂颗粒的输送的装置。
摘要:
Distillative separation of liquid mixtures of one or more water-insoluble substances which have boiling points higher than that of water and one or more substances which have boiling points lower than that of water or which form azeotropes having boiling points lower than that of water, wherein the mixture to be distilled is mixed with a quantity of water such that the boiling point of the water under the pressure applied limits the bottom temperature of the mixture of substances to be separated.
摘要:
The production of 3-methylpentane-1,5-diol by hydroformylation of 2-methylbut-1-en-4-ol with carbon monoxide and hydrogen at elevated temperature and superatmospheric pressure in the presence of a rhodium carbonyl complex which has been modified by a tertiary organic phosphine followed by hydrogenation of the 2-hydroxy-4-methyltetrahydropyran at elevated temperature and superatmospheric pressure in the presence of a hydrogenation catalyst.
摘要:
A dividing-wall column having a dividing wall which is essentially disposed along the long direction of the column is proposed, which divides the column interior into a feed part, a take off part, an upper shared column part and a lower shared column part, with feed in whole or in part in the vaporous state of a mixture to be separated between the upper region of the feed part and the lower region of the feed part and/or side stream take off in whole or in part in the vaporous state between the upper region of the take off part and the lower region of the take off part, where if feed is in whole or in part in the vaporous state the cross-sectional area of the upper region of the feed part is increased by plane-parallel displacement of the dividing wall toward the upper region of the take off part, and/or if the side stream take off is in whole or in part in the vaporous state, the cross-sectional area of the lower region of the take off part is increased by displacement of the dividing wall toward the lower region of the feed part, in such a manner that the F factor is substantially the same in all column regions.
摘要:
A process is described for preparing tetrahydrogeranylacetone in which pseudoionone, geranylacetone and/or dihydrogeranylacetone in a liquid phase, in which particles of a catalyst which is capable of preferentially hydrogenating carbon-carbon double bonds over carbon-oxygen double bonds are suspended, is conducted through a device which inhibits the transport of the catalyst particles in the presence of a hydrogen-containing gas.
摘要翻译:描述了一种制备四氢ger anyl anyl A A is ger ger ger through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through through 在含氢气体的存在下抑制催化剂颗粒的输送的装置。
摘要:
The fixed-bed catalyst comprises palladium and selenium or tellurium or a mixture of selenium and tellurium on a silicon dioxide support and has a BET surface area of from 80 to 380 m2/g and a pore volume of from 0.6 to 0.95 cm3/g in the pore diameter range from 3 nm to 300 &mgr;m, with from 80 to 95% of the pore volume being in the pore diameter range from 10 to 100 nm. It is prepared by impregnating a silicon dioxide support with a solution of a palladium compound and a selenium compound or tellurium compound or a mixture of a selenium compound and a tellurium compound, drying it and reducing it in the presence of hydrogen. The catalyst is used, in particular, for isomerizing 3-buten-1-ol compounds.
摘要:
The preparation of 3-alkoxycarbonyl propenals and 3-dialkoxymethyl propenals of the general formulae Ia and Ib respectively: ##STR1## (R.sup.1 =C.sub.1 -C.sub.3 -alkyl group; R.sup.2 and R.sup.3 =hydrogen, methyl, or ethyl; and R.sup.4 and R.sup.5 =C.sub.1 -C.sub.4 -alkyl groups, which may be joined to form a 5-membered or 6-membered ring), is effected by reacting a corresponding alcohol of the general formula IIa or IIb ##STR2## with oxygen or an oxygen-containing gas in the gas phase in the presence of a metal from Group IB of the Periodic Table or a compound of one such metal acting as catalyst.The target products serve as intermediates for the synthesis of carotenoids.