Oil Lemon-grass

The former is the more probable constitution. Citral as found in commerce, is probably almost invariably a mixture of the two isomers, which are very similar in their general characters. It occurs to a considerable extent in various essential oils, being the principal constituent of lemon-grass oil, and of the oil of Backhmisia citriodora, and occurring to the extent of about 4 to (i irer cent, in lemon oil, which owes its characteristic flavour to this aldehyde. 

The purest specimens which have been prepared of natural citral, either from lemon-grass oil, lemon oil, or the oil of Tetranthem citrata, have the following characters —... 

Methyl-heptenone, CgH, 0, occurs in various essential oils, especially lemon-grass oil, in which it is associated with, and difi cult to separate from, the aldehyde citral. 

A process tor the manufacture of artificial essence of violets consisting in causing lemon-grass oil, alcohol, acetone, and concentrated solutions of salts of hypochlorous acid to react on one another at the boiling temperature. 

The determination of citral in lemon-grass oil by the neutral sulphite absorption process ves results some 4 per cent, lower than those obtained by the bisulphite method, but the latter is that usually adopted in commerce, though, as alreadv stated, the former is official in the new Britiih Pharmacopmia. 

Citral Lemon grass oil, mandarin oil Chelidonic acid Asparagus, Celandine, anemone... 

Natural citral is nearly always a mixture of the two isomers. It occurs in lemon-grass oil (up to 85%), in Litsea cubeba oil (up to 75%), and in small amounts in... 

Natural aroma chemicals Isolation and purification via physical processes Citral from lemon grass oil, eugenol from cloves, menthol from Mentha species... 

One of the principal components of lemon grass oil is limonene, C10H16. When limonene is treated with excess hydrogen and a platinum catalyst, the product is an alkane of formula CioH2o- What can you conclude about the stmcture of limonene ... 

Several of the carotenoids are now commercially synthesized and used as food colors. A possible method of synthesis is described by Borenstein and Bunnell (1967). Beta-ionone is obtained from lemon grass oil and converted into a C14 aldehyde. The C14 aldehyde is changed to a C16 aldehyde, then to a C19 aldehyde. Two moles of the C19 aldehyde are condensed with acetylene dimagnesium bromide and, after a series of reactions, yield p-carotene. 

Citral A (Geranial) Citral B(Neral) = trans- cis-3,7-Dimethyl-2,6-octadienal) (monoterpene) Myrcia acris (bay oil) (Myrtaceae), Citrus Andropogon citratus (lemon grass oil) (Poaceae), Rosa spp. (rose oil) (Rosaceae), Citrus lirrwn (lemon peel), C. sinensis (orange) (Rutaceae) [flower], Verbena triphylla (verbena) (Verbenaceae) [antiseptic]... 

Geraniol is a constituent of rose and geranium oils and citral is in lemon and orange oils and lemon-grass oil. When citral condenses with acetone, with loss of water, a product known as pseudo-ionone is obtained. 

Lemon grass oil Rose oil Andropogon citratus.. Rose ... 

Citral, a fragrant terpene aldehyde made up of two isoprene units, is the main component of the steam-volatile fraction of lemon grass oil and is used in a commercial synthesis of vitamin A. 

Onawunmi GO. In vitro studies on the antibacterial activity of phenoxyethanol in combination with lemon grass oil. Pharmazie 1988 43 42 4. 

Fig. 3 The separation of lemon grass oil by temperature programming and by flow programming.

The lipidic vitamins (ref.84) include vitamin A (32), a substance intrinsic to the physiology of vision, vitamin E (83), a natural protective antioxidant, and vitamins K, (84) with Kj (85), antihemorrhagic compounds, each of which is derivable from an initial natural product intermediate. Although traditionally a -ionone obtained from citral (a major constituent of lemon grass oil) was used for the synthesis of vitamin A, a synthetic source has now replaced this in a process which also gives /g-carotene. In one method the Cl4 aldehyde in that process is reacted with a C6 eneyne component and selective hydrogenation followed by dehydration and isomerisation affords the final product (ref.85). 

Citral is a mixture of the cis- and trans-isomer aldehydes geranial and neral, which are very important as widespread components in various flavours. The origin assignment to the main natural sources, Litsea cubeba oil and lemon grass oil, respectively, can easily be performed, because lemon grass (Cymbopogon citratus) is a C4-plant, providing 8 C-values of about -12%c, whereas 8 C-values around -26%o are expected... 

The two oils were formerly the main source of natural citral, obtained as a ca. 4 1 mixture of geranial and neral by distillation [463, 466a, 466b]. However, lemon-grass oil has declined in commercial importance due to the competitive synthesis of citral and isolation of natural citral from Litsea cubeba oil. Today, a few 100 t/ yr are still produced. In addition to being processed into citral, it is used to some extent for perfuming soap and household products. 

Lemon grass A tropical grass (Cymbopogon citratue) which yields lemon grass oil. 

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