| Popis: |
Glycols such as neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, and hydroxypivalyl hydroxypivalate are used in the synthesis of polyesters and urethane foams. Commercial preparation of neopentyl glycol can be via an alkali-catalyzed condensation of isobutyraldehyde with 2 moles of formaldehyde (crossed Cannizzaro reaction). A number of derivatives of neopentyl glycol have been prepared; some show promise for commercial applications. 2,2,4-Trimethyl-1,3-pentanediol can be produced by hydrogenation of the aldehyde trimer resulting from the aldol condensation of isobutyraldehyde. The manufacture of 1,4-cyclohexanedimethanol can be accomplished by the catalytic reduction under pressure of dimethyl terephthalate in a methanol solution. Hydroxypivalyl hydroxypivalate may be produced by the esterification of hydoxypivalic acid with neopentyl glycol or by the intermolecular oxidation–reduction (Tishchenko reaction) of hydroxypivaldehyde using an aluminum alkoxide catalyst. Polyester resins are useful for preparation of coatings exhibiting a combination of hydrolytic stability, excellent weather resistance, and good flexibility. Keywords: Neopentyl glycol; Trimethylpentandiol; Cyclohexanedimethane; Hydroxypivaloly hydroxy pivalate; Resins; Foams; Marine coatings; Flame retardants |
