Geranyl acetate

Some of the other eucalyptus oils of commercial importance iaclude the Chinese eucalyptus, a camphor/ciaeole-type oil E. citriodora Hook, a citroaeUal-type oil E. staigeriana F.v. Muel., a citral-type oil and E. macarthuri H. Deane Maiden, a geranyl acetate-type oil. 

Acid-catalyzed esterification of nerol and geraniol with acid anhydrides produces the corresponding esters. The acetates and isobutyrates are also avaUable commercial products. U.S. production of neryl acetate [141-12-8] in 1993 was 18 t at a price of 11.56/kg and that of geranyl acetate [105-37-3] was 132 t at a price of 9.86/kg (67). 

Geranyl acetate (a diene) takes up 2 moles of hydrogen unselectively in 48 hours to give the saturated acetate, 3,7-dimethyloctyl acetate, bp 109-110712 mm, 1.4261. (Geraniol itself has an allylic hydroxyl and appears to suffer decarbonylation under these reaction conditions.)... 

The oil ooDtaiiiB about d per cent, ot geranyl acetate, pineue, cymene, Iree gerauiol. eucalyptol, traces of pbunol fcarvaerol ), and au aldehyde whieh is probably cuminic aldehyde. 

In the manufacture of geranyl acetate on a commercial scale it would not pay to make it absolutely pure, so that samples as met with in the ordinary way are not quite pure geranyl acetate. The acetylisation process, by which esters are made, is not always a quantitative one, and in some cases it is impossible to acetylate an alcohol to its full theoretical extent. Commercial samples, however, contain 95 per cent, or more of true ester, and should have the following characters —... 

Allylic acetates of either geranyl acetate or neryl acetate reacted with the sodium salt of methyl phenylsulfonyl acetate in the presence of tetrakis(triphenylphosphine palladium) affording the corresponding olefin, with a retained geometry at the primary carbon... 

For substituted allylic systems, both a- and y-substitution can occur. Reaction conditions can influence the a- versus "/-selectivity. For example, the reaction of geranyl acetate with several butylcopper reagents was explored. Essentially complete a- or y-selectivity could be achieved by modification of conditions.28 In ether both CuCN and Cul led to preferential "/-substitution, whereas a-substitution was favored for all anions in THF. 

Kanasawud and Crouzet have studied the mechanism for formation of volatile compounds by thermal degradation of p-carotene and lycopene in aqueous medium (Kanasawud and Crouzet 1990a,b). Such a model system is considered by the authors to be representative of the conditions found during the treatment of vegetable products. In the case of lycopene, two of the compounds identified, 2-methyl-2-hepten-6-one and citral, have already been found in the volatile fraction of tomato and tomato products. New compounds have been identified 5-hexen-2-one, hexane-2,5-dione, and 6-methyl-3,5-heptadien-2-one, possibly formed from transient pseudoionone and geranyl acetate. According to the kinetics of their formation, the authors concluded that most of these products are formed mainly from all-(E) -lycopene and not (Z)-isomers of lycopene, which are also found as minor products in the reaction mixture. 

The epoxidation of nonconjugated olefins is slow123,124 and shows reduced enantioselectivity as compared with the epoxidation of conjugated olefins. For example, enantioselectivities from the epoxidation of (Z)-l-cyclohexyl-1-propene, 3,3-dimethyl-l-butene, and geranyl acetate are 82% (with (34)), 70% (with (34)),123 and 53% (6,7-epoxide, with (26)),124 respectively, and yields of the epoxides are modest. 

Surprisingly, linalyl acetate (R = OAc) fails to undergo reduction under these conditions instead, it rapidly decomposes through cyclization and polymerization pathways.205 The same reaction conditions transform geranyl p-tolyl sulfone (R = S02C6H4Me-/ ) into a mixture of 7% reduced and 93% cyclized products within 20 hours, whereas geranyl acetate (R = OAc) gives only a 20% yield of cyclized and no reduced product (Eq. 95) 205... 

Initial studies on the application of these catalysts to allylic substitution reactions showed that the arenethiolate moiety functions as an excellent nontransferable group, and that the regioselectivity can be completely reversed by suitable changes in the reaction parameters [33]. If the reaction between geranyl acetate and n-BuM gl was carried out inTHFat—30°C with fast addition of the Grignard reagent to the reaction mixture, complete a selectivity was obtained. Raising the tempera-... 

Terpenoid DBPs were investigated by Joll et al. [124] and Qi et al. [125]. The main ozonation product of 2-methylisobomeol was camphor, which was further oxidized to formaldehyde, acetaldehyde, propanal, buntanal, glyoxal, and methyl glyoxal [125]. Chlorination of p-carotene, retinol, p-ionone, and geranyl acetate resulted in the formation of THMs [124]. 

Oxidation of 1,5-dienes to c -tetiahydrofurandiols was accomplished with RuO /aq. Na(10 )/acetone-EtOAc thus 2,5-dimethyl-1,5-hexadiene gave tetrahydrofurandiol, geranyl acetate yielded cw-tetrahydrofurandiol, and trans, tra 5-2,6-dimethyl-2,6-octadiene-l,8-diol diacetate (1) gave tetrahydrofuran ketol diacetate (2) (Fig. 3.12 cf. mech. Ch. 1) [174],... 

The isoprenoid polyenes famesyl acetate, geranyl acetate and squalene underwent oxidative poly cyclisation to bis-, tris- and penta-tetrahydrofurans with RuO /aq. Na(IO )/CH3CN-EtOAc [185]-[188]. This oxidative polycyclisation of squalene with RuO was shown to lead to the cis-threo-cis-threo-trans-threo-trans-threo-trans penta-tetrahydrofuranyl diol product, this configuration being determined by 2D-NMR (Fig. 3.14) [185]-[188] cf mech. Fig. 1.8 [185]. 

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