Allo-ocimene

By heat, ocimene is converted into allo-ocimene, which is probably a stereoisomeric compound. 

Consider now the 1,1,6,6-tetramethylated derivative of (Z)-l,3,5-hexatriene (83), a species more properly named (Z)-2,6-dimethyl-2,4,6-octatriene and occasionally and trivially called ds-allo-ocimene . To estimate its enthalpy of formation, let us use simple olefin additivity along with ... 

All-in dyeing method, 9 177 Allinger force fields, 26 744, 745 All-in paste, 9 216 Allocation methods, in life cycle assessment, 24 815 Allomone, 24 473 Allo-ocimene, 24 490, 495 oxidation of, 24 491 Allo-ocimene diepoxide, 24 491 Allo-ocimene epoxide, 24 491 Allo-ocimenols, isomeric, 24 490 All-organic transistors, 22 222-223 D-Allose, 4 698... 

After-reactions such as Hock-Cleavage or dehydration may become predominant at room or higher temperatures. While, for example, hydroperoxide 278 is cleaved to two molecules of cyclohexanone (280) only in the presence of acid,206 photosensitized oxygenation of allo-ocimene (281),220 homoverbenene (286),198 sorbic acid methyl ester... 

Monoterpenes are formed from two attached isoprene 3 units 2,6-dimethyloc-tane as the simplest skeleton. Thus, they can be acyclic or linear like -myrcene 4, ( )-/l-ocimene 5, (Z)-/l-ocimene 6, and allo-ocimene 7 (Structure 4.3). Or they can be cyclic, meaning ring-forming, such as in the simplest form like p-menthane 8 or p-cymene 9. Monocyclic 8, 9, bicyclic (5-3-carene 10 and tricyclic tricyclene 11 type monoterpenes are found in essential oils [1-4, 6-14, 16-23,38,39, 42, 47, 48]. 

Observing a process, scientists and engineers frequently record several variables. For example, (ref. 20) presents concentrations of all species for the thermal isomerization of a-pinene at different time points. These species are ct-pinene (yj), dipentene ( 2) allo-ocimene ( 3), pyronene (y ) and a dimer product (y5). The data are reproduced in Table 1.3. In (ref. 20) a reaction scheme has also been proposed to describe the kinetics of the process. Several years later Box at al. (ref. 21) tried to estimate the rate coefficients of this kinetic model by their multiresponse estimation procedure that will be discussed in Section 3.6. They run into difficulty and realized that the data in Table 1.3 are not independent. There are two kinds of dependencies that may trouble parameter estimation ... 

The common terpene names of a few acyclic hydrocarbons indicate the need for more precise names. For example, the name geraniolene, because of the "ol, suggests the presence of an OH group and some relation to the geraniols. From the name dihydromyrcene and a knowledge of the structure of myrcene, one cannot be sure where the two hydrogens have been added. The prefix alio- in allo-ocimene implies the more stable isomer, but knowledge of the structure of ocimene is insufficient to enable one to draw the correct formula for allo-ocimene. 

Rule 3. If two double bonds are present, the ending of the name will be diene if three double bonds are present, the ending will be triene. These endings replace the ending ane in the name of the saturated fundamental chain for euphony, the letter fta sometimes precedes these endings — for example, the name octane for the eight-carbon fundamental chain becomes octadiene for dihydromyrcene (No. 3, Chart 3) and octa triene for allo-ocimene (No. 5, Chart 3). 

Rule 5. The systematic names for acyclic compounds are single words and not two-part names — for example, the isomeric geraniolenes (Nos. 1A and IB, Chart 3) are dimethylheptadienes allo-ocimene is 2,6-dimethyl-2,4,6-octatriene. 

The common terpene names for acyclic terpene hydrocarbons are not sufficiently precise to indicate their structures or relationships among derivatives. It is recommended therefore that use of these names be discouraged, although the names allo-ocimene and myrcene will still be convenient for limited usage for commercial products. 

The volatiles showed variation in different environments. The composition of the oil from the fresh aerial parts of A. graveolensvai. secalinum (at the flowering stage) obtained from three locations in Egypt revealed that the main components were a- and /3-pinene, myrcene, limonene, cis-jl- ocimene, y-terpinene, cis-allo-ocimene, frans-farnesene, humulene, apiol, /3-selinene, senkyunolide and neocnidilide (Saleh et al., 1985). The chief component in the essential oils from fruits, and to a lesser extent in the leaves and stems, was limonene, whereas the roots and tubers had more frans-ocimene, 3-methyl-... 

ALLO-OCIMENE TENPIN HYDRATE TENPENE ETHENS PINE OIL MALEIC RESINS OIL ADDITIVES [Pg.1286]

Cyclization of allo-ocimene, using alkali metal amines, may give cycloheptadienes or acyclic dienes depending upon the conditions used 1,2,4-trimethylcyclohepta-1,3-diene may be obtained exclusively with sodium-piperidine, and 2,6-dimethylocta-2,4-diene (predominantly trans) is the major product using sodium-morpholine.129 The Prins formaldehyde reaction on myrcene (12), on the chelo-tropic adduct (42), and on the Diels-Alder adduct (43), has been investigated 130... 

C N.m.r. chemical shifts and spin-relaxation times have been reported for /3-cyclocitral.246 Mass spectral data have been recorded for a -pyronene (147), which fragments similarly to allo-ocimene through common ions.247 Brief acid-catalysed treatment of a-pyronene (147) gives predominantly the diene... 

In the course of an examination of the autoxidation of terpene hydrocarbons, Bardyshev and Shavyrin have found, predictably, that those containing conjugated double bonds e.g. allo-ocimene, myrcene) are oxidized most rapidly, those with isolated double bonds or cyclopropane rings more slowly e.g. limon-ene, carene), and those with a single double bond slowest e.g. pinene). The effect of light, heat, and inhibitors was studied. ... 

Dimethyloctanes.— The full account of the synthetic work on achillene (see Vol. 1, p. 9) includes a technique for improvement of the yield of natural cfs-achillene (12) by irradiation of the trans-compound (11), in the presence of benzophenone, the equilibrium mixture containing 45 % ds-achillene. Thermal isomerization of cis-j8-ocimene (13) [= (16)] yields 6-cis-allo-ocimene (14) without any trans-isomer (15) this is presumably because the preferred conformer (16) has the bulky isobutenyl group in a pseudo-equatorial position (the 6-trans-... 

Hydride shifts in the allo-ocimene series account for the thermal interconversions (below 300 °C) of the trienes (23) and (24) and also the cis-trans isomerism (24) — (25), probably via (26), whereas at higher temperatures (25) yields... 

Epoxidations, carbene additions, etc. of 2,3-epoxycitral have been studied.209 A very detailed investigation of the dye-sensitized photoxidation of a-nerol (92) showed the formation of the diols (93) and (94) with no cyclized products.210 Allo-ocimene and myrcene on autoxidation in DMF or DMSO give an odd variety... 

The quantitative conversion of dipentene and 3-pinene to form polymers stirred interest in (1) the pyrolysis of a-pinene to dipentene and allo-ocimene (34) and (2) the synthesis of B-pinene from a-pinene (35). However, due to the availability of citrus limonene as a supplemental source for dipentene, the pyrolysis scheme is no longer economically attractive. 

The structure of the major FeCla-catalysed ene adduct of chloral to (15,55)-(-)-/3-pinene (Vol. 8, p. 54) is (209). Preferred ene reaction of PhS02NS0 with 8-pinene has been used for the almost quantitative separation of a- and /8-pinene another application of this reaction allows the conversion of a-pinene into jS-pinene via a triple allylic transposition sequence of ene-reaction, reduction, reductive silylation, and hydrolysis/ Ene reactions of jS-pinene under pressure have been observed (74—100% yields) at room temperature thus limiting, for example, retro-ene side-reactions. The full papers on a-pinene/allo-ocimene pyrolysis (c/. Vol. 7, p. 12) and on the thermal rearrangement of (208 X = H or Me) have been published (Vol. 4, pp. 61, 62) (208 X = H) is reported to yield only (210) in contrast to unpublished observations of Prater who has reported the rearrangement of (210) to (208 X = H) and the formation of p-menthadiene derivatives from (208 X = H or 0-)6 ... 

Additive Allo- ocimene Myrcene Limo- nene Styrene LPS3... 

Some other common monoterpenoid hydrocarbons are shown in Figure 3.4. Citronellene is also known as dihydromyrcene. It does not occur in nature but is prepared by pyrolytic cracking of pinane. Hydration of the trisubstituted bond of citronellene produces dihydro-myrcenol which is used to provide fresh notes in perfumery. Further details of both of these processes are given in Chapter 9. a-Ocimene occurs in various essential oils such as those of basil, catnip and magnolia, while the P-isomer occurs in the leaf oils of lemon, orange and grapefruit and also in narcissus flowers. Allo-ocimene occurs in the leaves of sequoia trees and is the thermodynamically most stable of the three ocimenes since the double bonds are all in conjugation and as heavily substituted as possible. Double bonds can be isomerised under... 

Sasaki et al. have continued their work on 1,4-cycloadditions to monoterpenoids with a study of the reaction between propiolonitrile and allo-ocimene. In the presence of aluminium chloride, Diels-AIder addition of maleic anhydride to ocimene involves a second ring-closure, leading to the indane (Ih). "" Direct... 

---