6,7,16-Trihydroxyhexadecanoic acid

Aleuritic acid [/2S-erytAro-9,10,16-trihydroxyhexadecanoic acid] [533-87-9] M 304.4, m 100-101 . Crystd from aqueous EtOH. Hydrazide cryst from EtOH has m 139-140°. 

Shellac [124,125] is a natural resin used in very old times for varnishes and moulding compounds. The resin secreted by the lac insect, Kerriar paca, is collected by scraping the shellac-encrusted trees found in southern parts of Asia. It consists of a complex mixture of cross-linked polyesters derived from hydroxy acids, principally aleuritic acid (9,10,16-trihydroxyhexadecanoic acid). From a structural point of view, it appears that this material can be used as a crosslinking agent and/or as a monomer for developing dentrite-like polymers. The question is whether it is possible to produce this material from shellac by controlled hydrolysis. 

Polyesters are also produced naturally in some animals. In particular, shellac is a natural product that was for many years of major commercial importance as a moulding resin (e.g. for phonograph records) and a varnish. It is a constituent of lac, which is secreted by the lac insect of S. E. Asia and exuded by it onto trees. Shellac, which is obtained by purification from lac, is a complex polyester which can be hydrolysed to polyhydroxylic acids such as 9,10,16-trihydroxyhexadecanoic acid [97],... 

Shellac, which was used by Edison for molding his first photograph records and is still used as an alcoholic solution (spirit varnish) for coating wood, is a cross-linked polymer consisting largely of derivatives of aleuritic acid (9,10,16-trihydroxyhexadecanoic acid). Shellac is excreted by small coccid insects Coccus lacca), which feed on the twigs of trees in Southeast Asia. Over 2 million insects must be dissolved in ethanol to produce 1 kg of shellac. 

Synonyms DL-erytf7ro-9,10,16,-trihydroxyhexadecanoic acid 9,10,16-trihydroxypalmitic acid 8,9,15-trihydroxypenta-decane-1-carboxylic acid. 

Ci6H2g02, Mt 252.40, is not reported as being found in nature, in contrast to (Z)-7-hexadecen-16-olide, which occurs in ambrette seed oil (see p. 182) and which is also referred to as ambrettolide. It is a colorless to slightly yellow liquid, re 0 0.949 -0.957, re 0 1.477-1.482, with an intense and powerful musk odor. It is prepared by treating aleuritic acid (9,10,16-trihydroxyhexadecanoic acid) with trimethyl... 

Aleuritic acid [RX-erj Aro-9,10,16-trihydroxyhexadecanoic acid] [533-87-9] M 304.4, m 100-101 , pKsst 4.9. Crystallise this / S-acid from aqueous EtOH. It is soluble in MeOH, and forms a less soluble crystalline sodium salt. The methyl ester m 72-73°, b 235°/0.2mm, is best prepared by reaction with diazomethane and forms fine feathery needles it is soluble in MeOH, EtOH, CHCI3, Mc2CO, slightly soluble in CgH6 and insoluble in petroleum ether. The ethyl ester [6003-09-4] m 59°, crystallises in needles from EtOH. The hydrazide [6003-10-7] crystallises from EtOH and has m 139-140°. 

CAS 533-87-9 EINECS/ELINCS 208-578-8 Synonyms a-Aleuritic acid Aleuritic acid, tech. DL-Erythro-9,10,16-trihydroxyhexadecanoic acid Hexadecanoic acid, 9,10,16-trihydroxy- Hexadecanoic acid, 9,10,16-trihydroxy-, (R,S)-( )-... 

Synthetic aleuritic acid 9,10,16-Trihydroxyhexadecanoic acid 9,10,16-Trihydroxypalmitic acid 8,9,15-Trihydroxypentadecane-1 -carboxylic acid... 

DL-Erythro-9,10,16-trihydroxyhexadecanoic acid. See Aleuritic acid Erythrulose... 

Two or more hydroxy functions can be present in the principal chain, for example, in 9,10-di-hydroxyoctadecanoic acid and in ustilic acid (2,15,16-trihydroxyhexadecanoic acid) (Figure 12). 

A large number of hydroxy fatty acids occur in seed oils [71,856], and the best known of these is probably ricinoleic or 12-hydroxy-c/s-9-octadecenoic acid, which is the principle constituent of castor oil. Polyhydroxy fatty acids are present in plant cutins, while aleurltic or 9,10,16-trihydroxyhexadecanoic acid is one of the main components of shellac. Vernolic or 12,13-epoxy-c/s-9-octadecenoic acid is one of a number of epoxy fatty acids to have been detected in seed oils. 

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