Method of producing methyl methacrylate or methacrylic acid
AssigneeMitsubishi Chemical UK Limited
InventorNeil Tindale
Life of this patent
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Abstract
There is described a method of reducing polymer tar build-up in the production of methyl methacrylate and/or methacrylic acid by the acetone cyanohydrin process. In the method a stabiliser is contacted with the amide stage reaction medium. The stabiliser includes a hydrocarbon moiety capable of donating a labile hydrogen atom to a methacrylamide derivative capable of reaction with said labile hydrogen atom under the conditions in the said medium. The method herein is especially useful for the continuous production of methyl methacrylate and/or methacrylic acid.
Claims7
A method of reducing polymer tar build-up in the production of methyl methacrylate and/or methacrylic acid by an acetone cyanohydrin (ACH) process comprising an amide stage reaction medium, wherein a stabilizer is contacted with the amide stage reaction medium, which stabilizer includes a hydrocarbon moiety capable of donating a labile hydrogen atom to a methacrylamide derivative capable of reaction with said labile hydrogen atom under the conditions in the amide stage reaction medium, wherein the stabilizer is selected from one or more of the group consisting of an isoprenoid, 9,10-dihydroanthracene;
- adamantane;
- tert-dodecyl polysulfide;
- tetralin;
- fluorene;
- decalin;
- and 5,12-dihydrotetracene;
- dihydrocoumarin;
- anthrone;
- squalene;
- hemisqualane;
- camphor;
- 4-methylnonane;
- triacontane;
- bicyclohexyl;
- petroleum diesel;
- butyl cyclohexane;
- and decane.
A method of producing methyl methacrylate or methacrylic acid comprising the steps of:
- a. contacting acetone cyanohydrin (ACH) with an excess of concentrated sulphuric acid to produce a mixture of sulphatoisobutyramide (SIBAM), hydroxyisobutyramide (HIBAM) and optionally methacrylamide;
- and
- b. thermally converting SIBAM and/or HIBAM to methacrylamide in concentrated sulphuric acid medium;
- and
- c. contacting the methacrylamide with water or with water and methanol;
- wherein a stabilizer is present during step b, which stabilizer is added as a hydrocarbon moiety capable of donating a labile hydrogen atom to a methacrylamide derivative capable of reaction with said labile hydrogen atom under the conditions in the said medium, wherein the stabilizer is selected from one or more of the group consisting of an isoprenoid, 9,10-dihydroanthracene;
- adamantane;
- tert-dodecyl polysulfide;
- tetralin;
- fluorene;
- decalin;
- and 5,12-dihydrotetracene;
- dihydrocoumarin;
- anthrone;
- squalene;
- hemisqualane;
- camphor;
- 4-methylnonane;
- triacontane;
- bicyclohexyl;
- petroleum diesel;
- butyl cyclohexane;
- and decane.
Dependencies are inferred from the claim text.