| 摘要 |
1394973 Acrylate esters CELANESE CORP 2 Aug 1973 [3 Aug 1972] 36700/73 Heading C2C An esterification process wherein acrylic acid is esterified with an alkanol having from 1 to 10 carbon atoms to form an ester of acrylic acid with the alkanol, there being formed oligomeric by-products comprising at least one of (III) esters of (I) and of (II) with the said alkanol, and wherein R is an alkyl, cycloalkyl or substituted alkyl group corresponding to the said alkanol and n is an integer from 1 to 10; comprises the step of converting the said oligomeric by-products to a product comprising at least one of acrylic acid, the said alkanol, and the monomeric acrylate of the said alkanol by a method which comprises heating the said oligomeric byproducts, in a liquid phase containing an effective amount of an inhibitor against vinyl-type polymerization, to a temperature of at least 180‹ C. (e.g. between 200‹ and 250‹ C. for at least 1 minute). The process may be effected batchwise or continuously, preferably the latter by (a) introducing acrylic acid and the said alkanol into a still-reactor, (b) reacting the alkanol and acrylic acid in the said reactor in the presence of an effective amount of a material which is an inhibitor against vinyl-type polymerization (e.g. hydroquinone, phenothiazine, pmethoxyphenol), (c) distilling a product vapor comprising the said acrylate ester out of the reactor while forming in the base of the reactor a residue comprising ester-type oligomers as defined above and (d) converting at least a portion of the said oligomers to a product comprising at least one of acrylic acid and the said acrylic ester by a method which comprises heating the said residue, in the liquid phase and in the presence of an effective amount of a material which is an inhibitor against vinyltype polymerization, to a reaction temperature of at least 180‹ C. and then holding said heated residue at said reaction temperature for a reaction period of at least 2 minutes, the residue optionally being recycled to the still reactor as feedstock for the preparation of additional quantities of acrylate ester. The examples prepare n-butyl and 2-ethylhexyl acrylates. |
