OXIDATION OF ISOBUTYLENE  (Methacrolein and Methacrylic Acid)

Much like the oxidation of propylene, which produces acrolein and acrylic acid, the direct oxidation of isobutylene produces methacrolein and methacrylic acid. The catalyzed oxidation reaction occurs in two steps due to the different oxidation characteristics of isobutylene (an olefin) and methacrolein (an unsaturated aldehyde). In the first step, isobutylene is oxidized to methacrolein over a molybdenum oxide-based catalyst in a temperature range of 350–400°C. Pressures are a little above atmospheric:

In the second step, methacrolein is oxidized to methacrylic acid at a relatively lower temperature range of 250–350°C. A molybdenumsupported compound with specific promoters catalyzes the oxidation.

Methacrylic acid is esterified with methanol to produce methyl methacrylate monomer. Methacrylic acid and methacrylates are also produced by the hydrocyanation of acetone followed by hydrolysis and esterification .

Ammoxidation of isobutylene to produce methacrylonitrile is a similar reaction to ammoxidation of propylene to acrylonitrile. However, the yield is low.

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