Synthesis of Sym-Homopinic Acid

Abstract

The oxidation of / -pinene, a constituent of turpentine, to pinonic and pinic acids has recently been investigated by this laboratory. The alkyl esters of these acids were found to be suitable for use in the synthetic lubricant and plasticizer field (1). Pinonic acid (I), a methyl keto monobasic acid, is readily prepared from alpha-pinene by oxidation with permanganate (2) or ozone. Its structure indicates that sz/m-homopinic acid (2,2-dimethylcyclobutane-l ,3diacetic acid) (II), a Cio dibasic acid, could be prepared from pinonic acid by the use of the Willgerodt reaction (3). Guha and Ganapathi (4, 5) prepared irans-sz/m-homopinic acid from czs-diethyl norpinate by reduction to the glycol, conversion of the glycol to the dibromide, thence to the dinitrile, followed by saponification to the acid.Esters of sz/m-homopinic acid should be valuable as synthetic lubricants and plasticizers. Because of its higher molecular weight and symmetrical nature, this acid should have some advantage over pinic acid in the preparation of plasticizers and synthetic fibers.

Hydroxyalky and Olefinic Substituted gem-Dimethylcyclobutanes

“…The only reasonable explanation for variations in composition shown in Table VI is in the purity of the acid (IV) used as raw material. Recent work in this laboratory (13) has shown that yvm-homopinic acid as prepared (6,14) from «W/-pinonic acid is probably a mixture of cis and trans isomers in a ratio of about 7 to 3. Purification by crystallization changes this ratio.…”

Pinonic Acid—a Promising Chemical Raw Material

“…From 34 pounds (0.25 mole) of apinene and 80 pounds (0.505 mole) of potassium permanganate, 28 pounds of pinonic acid (61% yield) and 10.5 pounds of by-product 1-hydroxypinocamphone (II) (25% yield) have been obtained. The latter can be oxidized (30) by acid permanganate to give another 10 pounds of acid which raises the yield to 83%. Materials cost calculations for pinonic acid (Table II) are based upon experience to date.…”

“…Ruzicka (28) has prepared pinonic acid cyanohydrin (XI) in good yield and converted it to 5 -isopropyl -2 -methylheptanedioic acid (XII). Pinonic acid has been converted to rym-homopinic acid (XVII) by the Willgerodt reaction (30). By the same method, homoterpenyl methyl ketone has been converted to the valeric acid y-Iactone (VII) (13).…”

Pinonic Acid

“…1, p. 1, 1948. (11) Ford, E. W., and Cooper, L. V., India Rubber World, 125, 55-60 (1951) . (12) Hulswit, W. H" Jr., and Wiechman, H. C" U. S. Patent 2,392,-590 (1946).…”