Acyclic monoterpene alcohols

While earlier it was generally thought that the acyclic monoterpene alcohols 242-245 are derived from the host tree s oleoresin component, myreene [453], more recent results clearly show that at least in some species they are produced denovo [454-456]. 

Acyclic monoterpene alcohols are present in many essential oils and can be isolated by distillation, although nowadays, they are often synthesized from other sources. Geraniol and linalool (Fig. 7) are the most important monoterpene alcohols and together with nerol are the primary products in terpene biosynthesis [44]. a-Terpineol is a frequently used cyclic monoterpene alcohol in the fragrancing industry because of its typical lilac odor and is also partly responsible for the typical... 

Monoterpenoids are responsible for fragrances and flavors of many plants and thus their products are used in perfumery and as spices. To date over 1,500 monoterpenoids are known, and these constitute acyclic, monocyclic, and bicyclic monoterpenoids (32), which occur in nature as hydrocarbons, alcohols, aldehydes, and carboxylic acids and their esters. Several acyclic monoterpenoid hydrocarbons are known, and these include trienes such as 3-myrcene (Cl), a-myrcene (C2), (Z)-a-ocimene (C3), ( )-a-ocimene (C4), (Z)-3-ocimene (C5), and ( )-P-ocimene (C6). 3-Myrcene and 3-ocimene are constituents of basil (Oci-mum basilicum, Labiatae) and bay (Pimenta acris, Myrtaceae), pettitgrain (Citrus vulgaris, Rutaceae) leaves, strobiles of hops (Humulus lupulus, Cannabaceae), and several other essential oils. Unsaturated acyclic monoterpene alcohol constituents of plants and their derived aldehydes play a signihcant role in the perfume industry. Some common acyclic monoterpene alcohols and aldehydes include geraniol (C7), linalool (C8) (a... 

Boidron (71) showed that there was a decrease in the concentration of acyclic monoterpene alcohols and oxides in grape juice which was fortified with these compounds and then inoculated with B. cinerea. After 25 days of fungal growth none of the added monoterpenes could be detected in the juice. Two proposals were put forward to account for these observations - (a) B. cinerea metabolized acyclic monoterpenes to oxides and a-terpineol, then degraded these postulated metabolites or (b) a chemical oxidation paralleled the attack by the fungus (71). 

CHronellols (3,7-dimethyloct-6- and -7-en-l-ol). CioHjoO, Mr 156.27, formula, see citronellals. Acyclic monoterpene alcohols, of which the /8-forms of both enantiomers occur in nature (3/ )(+)-/S- and (35)(-)-/S-C., bp. 224-224.5 °C, [a]o 5 (neat). Both have strong, rose-like odors. 

C iqH I gO, Mr 154.24, liquid with a pleasant, flower-like odor. Unsaturated, acyclic monoterpene alcohols [(2 )-form G. (2Z)-form nerol], G., bp. 230°C nerol, bp. 224-225 °C. G. and nerol undergo slowly changes on exposure to atmospheric oxygen. Geranyl pyrophosphate is an important intermediate in the biosynthesis of terpenes and steroids. 

Myosin see Muscle proteins Myrcene a triply unsaturated acyclic monoterpene hydrocarbon. M is a pleasant smelling liquid, M, 136.24, b.p.,2 55-56°C, p 0.8013, n 1.470. It is a component of many essential oils, and it is prepared for the perfumery industry by pyrolysis of p-pinene (from oil of turpentine). M. is al used commercially for the preparation of isomeric acyclic monoterpene alcohols and their acetates... 

Madyastha, K.M. and N.S.R. Krishna Murthy, 1988a. Regiospeci c hydroxylation of acyclic monoterpene alcohols hy Aspergillus niger. < 29 579-580. 

In order to obtain lactones from natural alkenols, we investigated the cyclocarbonylation of monoterpenic alcohols. The catalytic precursor is [PdCl2L2] in the presence of a slight excess of tin chloride and phosphine ligands. Dihydromyrcenol, a representative acyclic terpene containing a termi-... 

Acyclic monoterpenes geraniol in essential oils, perfume products and luxury foods, production from other terpene products, e.g. beta-pinene acyclic, double unsaturated alcohol, several possible reactions, occurrence as esters, typicjd rose odor... 

Molecular structures of monoterpenoids are present as three major types acyclic, monocyclic and bicyclic. Oxygenated derivatives of acyclic monoterpenes are more widespread in nature than acyclic monoterpenes themselves. Such derivatives are the monoterpene alcohols citronellol and geraniol, or the monoterpene aldehydes citronellal and geranial. Mononocyclic monoterpene hydrocarbons are exemplified by limonene, which is a major component of orange and lemon peel oils, and p-phellandrene, which is emitted by conifer trees under biotic stress. These compounds are relatively common in nature. Bicyclic monoterpenes are represented by the aforementioned a-pinene, one of the most abundant and important monoterpenes. 

Monoterpenes occur in plants in various structural forms some are cyclic while the others are acyclic. They also contain various types of functional group, and depending on their functional groups they can be classified as simple hydrocarbons, alcohols, ketones, aldehydes, acids or phenols. Some examples are cited below. 

The monoterpenes are subdivided into three groups acyclic, monocyclic and bicyclic (there is only one tricyclic terpene tricyclene). Each group contains hydrocarbon terpenes, terpene alcohols, terpene aldehydes, ketones, oxides etc... 

Isoprene (2-methylbnta-l,3-diene), a branched diunsaturated Cj hydrocarbon, is the bnilding block of a large family of open-chain and cyclic isoprenoids and terpenoids (Fig. 4.8). Essential oils of higher plants are enriched in monoterpenes (Cj ) with two isoprene nnits. Farnesol, an unsaturated alcohol, is an example of a sesquiterpene with three isoprene units. The acyclic diterpene phytol is probably the most abnndant isoprenoid on Earth. It occnrs esterified to chlorophyll a and some bacteriochlorophylls and is. 

Monoterpenes (Cio) are the simplest members of the terpene series. They result from the condensation of two isoprene units and may be acyclic, monocyclic, bicyclic or tricyclic. The monoterpenes can have another functional moiety like alcohol (geraniol, linalool, menthol, bomeol), aldehyde (geranial, cihonellal), ketone (menthone, carvone, thujone), ester (bomyl acetate, linalyl acetate), ether (1,8-cineol) and phenol (thymol, carvacol). In the case of optically active molecules, the proportions of the enantiomers vary largely from one species to another. 

---