82results about "Preparation from ketenes/polyketenes" patented technology

A process for producing a compound which is (3R)-hydroxybutyl(3R)-hydroxybutyrate of formula (I) which process comprises submitting, to enantioselective reduction, a compound of the following formula (II), (III) or (IV).

A process for producing a compound which is (3R)-hydroxybutyl (3R)-hydroxybutyrate of formula (I) which process comprises submitting, to enantioselective reduction, a compound of the following formula (II), (III) or (IV).

This invention provides an integrated multistep economical process for the production of vinyl acetate monomer (VAM) from acetic acid in the vapor phase. First, acetic acid is selectively hydrogenated over a hydrogenating catalyst composition to form acetaldehyde. Acetaldehyde so formed can be converted to ethylidene diacetate via reaction with acetic anhydride. In a subsequent step so formed ethylidene diacetate is thermally decomposed to form VAM and acetic acid. Alternatively, acetaldehyde formed in the first step can selectively be reacted with ketene to form VAM. In an embodiment of this invention reaction of acetic acid and hydrogen over platinum and iron supported on silica selectively produces acetaldehyde in a vapor phase at a temperature of about 300° C., which is selectively hydrogenated over platinum supported catalyst to form ethanol and dehydrated over NAFION catalyst to form ethylene at a temperature of about 185° C., which is mixed with molecular oxygen, acetic acid and reacted over a palladium / gold / potassium catalyst supported on titania to form VAM at a temperature of about 150° C. to 170° C.

The invention provides a preparation method of methyl acetoacetate. The preparation method sequentially comprises the following steps of: (1) fully dissolving methanol and a catalyst, then adding the mixture into an esterification reaction kettle, heating up, and dropwise adding ketene dimer; (2) after completing dropwise addition, insulating, and cooling to produce crude methyl acetoacetate; (3) rectifying the crude product to obtain the finished methyl acetoacetate. The preparation method is characterized in that the catalyst in the step (1) is an amine type ionic liquid catalyst which is selected from one or more of n-butylamine nitrate, n-butylamine acetate, ethylamine nitrate, ethylamine acetate, propylamine nitrate and propylamine acetate. According to the preparation method of methyl acetoacetate, the amine type ionic liquid catalyst is researched and is good in stability, the stability of methyl acetoacetate is enhanced under the action of the catalyst, the rectification yield of a product can be improved, the technological operations are simple, the raw material consumption is reduced, and the catalyst has obvious advantages and a positive effect.

The invention discloses a method for preparing methyl acetoacetate. The method comprises the following steps: adding a catalyst once, continuously adding ketene dimer and a methanol solution through a raw material feeding hole, continuously adding an extraction agent through an extraction agent feeding hole, simultaneously adding two materials into a reaction-extraction rectifying tower, and starting heating; carrying out total reflux so as to obtain the methanol solution through the tower top of the reaction-extraction rectifying tower and obtain a mixed liquid of the methyl acetoacetate, the catalyst and the extraction agent through the tower bottom of the reaction-extraction rectifying tower, and enabling the mixed liquid to flow into a decompression extraction tower from a tower-bottom discharging hole, so as to obtain a target product, namely the methyl acetoacetate from the tower top of the decompression extraction tower. Due to the arrangement of the reaction-extraction rectifying tower and the decompression extraction tower, the methyl acetoacetate is prepared by virtue of a reaction-rectification and extraction-separation integrated reaction, the materials are fed once, and the catalyst and the extraction agent can be recycled, so that the operation is simple, the cost is lowered, the purity and rate of the prepared methyl acetoacetate are high, and the energy consumption is reduced.