摘要:
Methanol can be substantially removed from dimethyl carbonate (DMC)/methanol mixtures by absorption on ion exchange resins. The enriched DMC is obtained as filtrate. The absorption is carried out at from -50.degree. C. to +100.degree. C. and 0.1-10 bar.
摘要:
Dialkyl carbonates can be prepared by the reaction of carbon monoxide with alkyl nitrites in a continuous gas phase reaction, using a platinum metal catalyst on an amorphous alumosilicate having a content of 30-80 atom% Al, based on the sum of Al and Si, as a support, which catalyst may optionally comprise additional material of a compound of antimony, bismuth, aluminium, copper, vanadium, niobium, tantalum, tin, iron, cobalt, nickel or a mixture of a plurality of these, and hydrogen halide being added in the course of the reaction intermittently or continuously. In this reaction, the dialkyl carbonates are formed with almost quantitative selectivity; the corresponding dialkyl oxalates cannot be detected in most cases.
摘要:
It has been found that cyclopentene and hydrogen bromide can be continuously reacted in a simple manner to give cyclopentyl bromide in good yields and good selectivities if the reaction is carried out in the presence of a heterogeneous catalyst. The reaction can be carried out continuously and unreacted cyclopentene and possibly other constituents can be recirculated to the reaction.
摘要:
Dialkyl carbonates can be prepared by reacting carbon monoxide with alkyl nitrites in a continuous gas phase reaction in the presence of a heterogeneous platinum metal catalyst, the activity of this catalyst being maintained by the addition of small amounts of halogen. The dialkyl carbonates are thus formed with almost quantitative selectivity and no deactivation of the catalyst occurs.
摘要:
C.sub.1 -C.sub.6 -Alkyl nitrites can be prepared by reacting nitrogen dioxide with C.sub.1 -C.sub.6 -alcohols, by, in a counterflow-operated column, feeding the alcohol or an alcohol/water mixture into the upper part of the column and the nitrogen dioxide or a nitrogen dioxide/inert gas mixture into the lower part of the column. The resulting alkyl nitrite is removed from the column as the top product and the co-formed nitric acid is removed from the column as the bottom product.
摘要:
A first alkanol having 1 to 3 C atoms or a mixture of this first alkanol with water or water itself can be separated off from oxygen-containing organic compounds having 3 to 7 C atoms from the group comprising second alkanols and dialkyl carbonates, which always have at least 2 C atoms more than the first alkanol, by permeation on membranes if a membrane obtained by plasma polymerization is employed.
摘要:
Dimethyl carbonate is obtained with a high selectivity and great constancy over time by reacting carbon monoxide with methyl nitrite in a continuous gas phase reaction in the presence of a heterogeneous catalyst prepared by the application to a suitable support of one or more palladium compounds of the formula[Pd(N(R.sup.1, R.sup.2, R.sup.3)).sub.n ]X.sup.1.sub.2 (I) ,wherein R.sup.1, R.sup.2, R.sup.3, X.sup.1 and n are as defined in the disclosure, optionally in combination with one or more promoters from the group consisting of the elements Fe, Co, Ni, V, Nb, Mo, Ta, Ti, Cu and Cr, the rare earths and/or compounds thereof, and/or with one or more promoters from the group consisting of alkali metal and alkaline earth metal halides.
摘要:
Heterosubstituted acetals of the formula ##STR1## can be obtained by reacting vinyl compounds of the formulaCH.sub.2 .dbd.CH-A.sup.1 (II)with alkyl nitrites of the formulaR.sup.1 --ONO (III.)The reaction is performed in the presence of palladium in metallic or bonded form and in alcohols or ethers as reaction medium at from 0.degree. to 120.degree. C.
摘要:
Substituted cyclohexanones of the formula ##STR1## where R.sup.1 to R.sup.5 are as defined in the description, can be obtained by catalytic hydrogenation of phenols of the formula ##STR2## where R.sup.1 to R.sup.5 are as defined in the description.The reaction is carried out at from 20.degree. to 250.degree. C., from 1 to 200 bar and in an ether as solvent. If desired, an alkaline alkali metal, alkaline earth metal or ammonium compound is used as additive.
摘要:
Alkyl carbazates of the formula R.sup.1 --O--CO--NH--NH.sub.2 (I) are prepared in an advantageous manner by reacting an alkyl carbazate of the formula R.sup.2 --O--CO--NH--NH.sub.2 (II) with alcohols of the formula R.sup.1 --OH (III) in the presence of a catalyst, where the symbols used in the formulae are as defined in the description.