Hexenyl acetate

To 2 mmol of freshly prepared ethereal LiCu(C.H3), are added 154 mg (1 mmol) of ( — )-m-5-melhyl-2-cyclo-hexenyl acetate (3a). [a]25 —2.7 (c = 3, CHC1,), in a centrifuge tube at 0°C. The mixture is kept at 0 °C for 8 h after which 1 mL of water is added. Methane is evolved and a reddish precipitate forms. After centrifuging, the supernatant liquid is decanted and concentrated, and the product trims-4 is isolated by preparative GC. Isolated yields range from 30% and 40%. However, it was reported in a similar reaction that the yields range from 90% and 95% 5. Analysis by capillary GC shows the product to be 99.5% trans-4 and 0.5% t -4. Capillary GC of the starting 3a shows the acetate 3a to be homogeneous except for a trace ( — 1.0%) of the trans-isomers. 

T)-2-octenyl acetate was identified from the volatiles produced by the adult female predatory bug, Geocorispunctipes that attracted male bugs. This compound comprised a significant portion of female volatiles. Other components in the extracts from adults of both sexes included (T )-2-hexenyl acetate, ( )-2-octenal and several saturated hydrocarbons but were not part of the attractant. Homogenized adults also yielded (T )-2-hexenal and (T)-4-oxo-2-hexenal whereas cast skins from late instar nymphs contained (T)-2-octenal, (T)-4-oxo-2-octenal, (T)-2-octenoic acid, and other saturated hydrocarbons. ... 

Grosjean, E., D. Grosjean, and J. H. Seinfeld, Gas-Phase Reaction of Ozone with tra/rx-2-Hexenal, tra/rx-2-Hexenyl Acetate, Eth-ylvinyl Ketone, and 6-Methyl-5-hepten-2-one, Int. J. Chem. Kinet., 28, 373-382 (1996). 

An understanding of olefin chemoselectivity in CM is also crucial when homologating 1,3-dienes, which represent a particularly challenging substrate class. In 2005, Grubbs and co-workers demonstrated that, by employing either an electronic or steric barrier to reaction, one of the olefins in a conjugated diene could be deactivated relative to the other for CM. For example, in the reaction of ethyl sorbate with 5-hexenyl acetate in the presence of 5 (I0mol%),... 

Trade Names. Inonyl acetate (Quest), Isononyl acetate (H R), Vanoris (IFF). trafis-2-Hexenyl acetate [2497-18-9]... 

The sensitivity of the antennal olfactory receptor system differs even between Colorado beetle populations (see Figure 5). The beetles of the field population in Wageningen are relatively more sensitive for cis-3-hexenyl acetate when tested than those of the laboratory stock culture. Beetles of the Utah population are relatively less sensitive for trans-2-hexen-1-ol and trans-2-hexenal than the individuals of the field population in Wageningen, and those insects obtained from the laboratory stock culture. The functional significance of these differences for the geographic variation in host plant range of this insect species needs further elucidation (21,22). 

Figure 3. Components trapped from the air over cut potato leaves. Carbon traps were extracted with 60 fxL of CSt IftL was used for CC (detector FID). GC conditions WCOT Carbowax 20M column, 50 m long temperature programmed 70-150 °C. Key a, trans-2-hexenal b, cis-3-hexenyl acetate c, cis-3-hexen-l-ol and d, tians-2-hexen-l-ol (14).

Figure 5. Mean EAG responses of three male and three female Colorado beetles from different populations to tta.ns-2-hexen-l-ol (t-2-H-l-ol), cis-3-hexen-l-ol (c-3-H-l-ol), ds-3-hexenyl acetate (c-3-H-ace), and tra.ns-2-hexeruil (t-2-H-al) at two dilutions in paraffin oil, 10 and 10 (v/v). Key A, laboratory stock culture B, field population Wageningen C, field population Utah vertical lines indicate 95% confidence intervals and, significant a/ P < O.OI (Mann-lVhitney V test).

Female antennae detected small amounts of ( )- -farnesene, (Z, )-a-farne-sene, methyl salicylate and germacrene D, while other more abundant compounds, such as (3Z)-hexenyl acetate and ( )- -ocimene, gave no significant antennal response [378]. 

The first study on the volatile composition of bacuri revealed linalool, 2-hep-tanone, and czs-3-hexenyl acetate as the most important flavour compounds [2]. Volatiles were isolated by a steam distillation-extraction of pulp. 

The main volatile components isolated from bacuri shells using various isolation methods, such as steam distillation and supercritical CO2 extractions were (Z)-linalool oxide, ( )-linalool oxide, 2-pentanone, 2-nonanone, ds-hexenyl acetate, methyl dodecacanoate, and several hydrocarbons, including bisabolene [46]. 

Large-scale synthesis of (Z)-3-hexenyl acetate in hexane with lipase, (Z)-3-hexenol and acetic acid was described by several authors [40-42]. (Z)-3-Hex-enyl acetate has a fruity odour and shows a significant green note flavour. It can be produced using lipase from Candida antarctica immobilised on an acrylic resin [40, 41] or using immobilised lipase from Mucor miehei [42]. The conversion was reported to be about 90%. 

Fig. 2.4. Chromatographic profiles of volatiles emitted by four plant species at different time periods after an attack by Spodoptem littoralis larvae. The labeled peaks are 1, (Z)-3-hexenal 2, ( )-2-hexenal 3, (Z)-3-hexenol 4, (Z)-3-hexenyl acetate 5, linalool 6, ( )-4,8-dimethyl-1,3,7-nonatriene 7, indole 8, ( )-/ -caryophyllene 9, ( ,)-o -bergamotene 10, ( >/3-farnesene 11, ( , )-of-farnesene 12, nerolidol 13, ( , )-4,8,12-trimethyl-1,3,7,11-tridecatetraene 14, of-pinene 15, /3-pinene 16, -myrcene 17, D-limonene 18, ( )-/3-ocimene 19, -sesquiphellandrene 20, germacrene D. Two internal standards, -octane and nonyl acetate, are labeled with IS1 and IS2, respectively.

It is now possible to understand the curious phenomenon whereby the reaction of palladium acetate with I in vacuo first rapidly produces a metal precipitate and then slows at about 20% conversion and finally stops with much of the palladium (II) unreacted. These stages in the reaction correspond to oxidation first by Pd3(OAc)6 and then by IVa with ultimate formation of the inert species Va. A complex mixture of hexenyl acetates is formed in the oxidation of which the major constituent l-hexen-2-yl acetate (VI) is 0.68 mole fraction of the whole mixture. Overall the mixture is closely similar to that obtained in the catalytic reactions of 02 described later, suggesting that the same active palladium-containing species is involved. Much of I is isomerized to a 5 1 mixture of trans- and ds-2-hexene (85% at 6 hrs) with only 3% each of the 3-hexene isomers. This aspect of the selectivity problem in which only one shift of the double bond takes place is also reproduced in the catalytic reaction, but oxygen suppresses the rate of isomerization relative to oxidation. 

Z)-3-Hexenyl acetate [2H3]acetate Guth and Grosch, 1993c... 

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