A Green Synthesis of Camphor - Fluttrbox
Camphor synthesis of camphor by retro-synthesis - Answers
An alternative proposal for the biosynthesis of the bornane series of bicyclic monoterpenes forms the basis of a new synthesis of camphor from p-menth-8-en-2-one (dihydrocarvone).
Synthesis of Camphor by the Oxidation of Borneol
a conclusion confirmed by its synthesis (see below). The Bredt formula is also supported by the synthesis of r-camphoric acid by G. Komppa ( 1901, 34, p. 2 47 2; 1903, 36, P. 433 2). In this synthesis ethyl oxalate is, condensed with ($-dimethyl glutaric ester, and the resulting diketoapocamphoric ester (I) is then methylated to diketocamphoric ester (2). The keto groups in (2) are converted in CH 2 groups as follows :- Sodium amalgam converts this ester into dioxycamphoric ester (3), which with hydriodic acid and phosphorus yields r-dihydrocamphoric acid. At 125Â° C. this compound combines with hydrobromic acid to form fi-bromcamphoric acid, which on reduction with zinc and acetic acid yields r-camphoric acid (4): ROzC CH C(CH3) 2 ' CH C02R, R02C CH C(CH3)2' C(CHa)' C02R CO CO CO CO (I) (2) H02C CH' C(CH3)2' C(CH2) ' C02H ? R02C CH' C(CHa)2' C (CH3) C02R CH2 CHz HC(OH) CH(OH) (4) (3) This series of reactions leads to a complete synthesis of camphor, since A. Haller ( 1896, 122, p. 446) has shown that camphoric anhydride (I) on reduction yields campholid (2), which by the action of potassium cyanide and subsequent hydrolysis of the nitrite formed is converted into homocamphoric acid (3), the calcium salt of which yields camphor (4) on distillation CsH1 4 "0->CSH1a? CO 2 / O-*CsH1a? COlH OzH?C81114(1 ? (x) (3) (4) Thus camphor and its oxidation products are to be represented as CH2-CH C12 (a) CH2' CH CO 2 H C02H C02H I C (CH3) 2 Pr) I I C(CH2)2 I C(CH3)2 CH2'C(CH3) CO (p), CH 2. C(CH3) C02H, CH2. C(CH3) C02H Camphor, Camphoric acid, Camphoronic acid.
Synthetically, camphor has been obtained by the dry distillation of the lead1) or calcium-) salts of homocamphoric (Haller's hydroxycamphocarboxylic acid). However, this synthesis was only a partial one, since the homocamphoric acid was obtained from a derivative of camphor. The complete synthesis of camphor was later successfully accomplished by Komppa3) who likewise succeeded in effecting the synthesis of camphoric acid.