Citronella citronellal

AI3-00203 Citronella Citronellal Citronellel 2,3-Dihydrocitral 3,7-Dimethyl-6-octenal 3,7-Dimethyl-6-octen-1-al D-Rhodinal EINECS 203-376-6 FEMA No, 2307 HSDB 594 NSC 46106 6-Octenal, 3,7-dimethyl- Rhodinal. Used in soap perfumery, manufacture of hydroxycitronellal, an insect repellant. Oil bpi = 47° d = 0.848-0,866 [a)S 11.50°. Lancaster Synthesis Co. Penta Mfg. PMC. 

Citronellal occurs naturally as the principal component of citronella oil and is used as an insect repellent... 

Harries and Comberg have also supplied much evidence, which, taken with the above-mentioned researches, places the chemical isomerism of citronellol and rhodinol practically beyond dispute. By ozonisation experiments decomposition products were obtained, which proved that natural citronellal, obtained from citronella oil, is a mixture of about... 

H. J. Prins has now isolated the two isomeric citronellals from Java citronella oil (see under citronellal). 

Citronellal which was originally termed citronellone, is one of the characteristic constituents of citronella oil, in which it occurs to a considerable extent. It can be prepared by shaking the essential oil with a hot solution of sodium bisulphite, and decomposing the resulting bisulphite compound by means of sodium carbonate and distilling the citronellal in a current of steam. Citronellal is optically active, and it is probable that the specimens isolated from natural sources are mixtures of the two optically active isomers, so that the actual theoretical rotation is not known with certainty. 

Citronellal prepared from Java citronella oil is laevo-rotatory to the extent of about - 3°. 

Until rather recently, our choice among chemicals repellant to insects was very limited (9), and some of the available remedies seem to have been almost equally repellent to their human users. The most familiar of them undoubtedly is the classical oil of citronella, a mixture of plant terpenes which consists principally of geraniol, citronellol, and citronellal. It is a remarkable coincidence that at least one insect species, an ant discussed by Dr. Happ, also makes use of some of these same terpenes as repellents against other insects. It biosynthesizes them de novo rather than simply taking them from plant sources. Many other examples of insect repellency have been observed (9), and Roth and Eisner (28) list over 30 compounds which have been identified as defense substances of anthropods. 

Citric acid activity (CAA) test, 15 405 Citric acid cycle, 6 632-633 Citrine, color, 7 337 Citrogypsum, 4 593 Citronella, 24 504 Citronellal, 3 232 24 532-533 hydration to hydroxycitronellal,... 

More recendy the cis and trans isomers of the mosquito repellent CIC-4, a mixture of citronella isomers, have been separated by preparative hplc and bioassayed for effectiveness (23). Chiral-phase capillary gas chromatography and mosquito repellent activity of some oxazolidine derivatives of (+)-and (— )-citronellal have been studied to find structure—activity relationships (24). Several 2-alkyl- -acetyloxalidines have been synthesized and tested against mosquitoes, with further efforts using nmr to determine the rotational isomers of the more active N-acetyl-2,2-dimethyloxazolidine (25). 

Synthesis of (+)- and ( )-Citronellol from the Citronellal Fraction of Essential Oils. (+)-Citronellal is obtained by distillation of Java citronella oil and is hydrogenated to (+)-citronellol in the presence of a catalyst (e.g., Raney nickel). Similarly, (zb)-citronellol is prepared from the ( )-citronellal fraction of Eucalyptus citriodora oil. 

Id 13.1°, occurs in essential oils in its (+) and (-) forms, often together with the racemate. (+)-Citronellal [2385-77-5] occurs in citronella oil at a concentration... 

Isolation from Essential Oils. (+)-Citronellal is obtained from citronella oils by fractional distillation. ( )-Citronellal is isolated from Eucalyptus citriodora oil when necessary, it is purified by using an addition compound, e.g., the bisulfite derivative. 

Citronella, Ceylon Cymbopogon nar-dus (L.) W. Wats. Citronellal (3-6), geraniol (15-23), citroneUol (3-9)... 

Citronella, Java Cymbopogon win-terianus Jowitt. Citronellal (30-45), geraniol (20-25), citroneUol (9-15)... 

Citronellol Manufacture. Citronellol is found widely in nature and in both optically isomeric forms. Prior to the development of synthetic citronellol, this alcohol was obtained from certain oils of the Rosaceae family or by hydrogenation of citronellal isolated from citronella oil. Citronellol has a floral odor resembling that of roses. 

The method for preparing (-)-menthol (73) from (+)-citronellal (68), which can be fractionally distilled from citronella oil, is cydization by the ene-reaction. The reaction can he done thermally or using alumina and silica catalysts (145—147). 

Citronellal Manufacture. Natural sources of citronellal are citronella oil and Eucalyptus citridora. In 1995 the price of citronella oil from Java and China was 18.90/kg and the price of citronellal in 25-lb cans was 15.40— 23.10/kg (69). 

The determination of aldehydes and ketones is of importance in the analysis of those essential oils characterised especially by aldehydic or ketoruc principles, e g.,the citral contained in lemon and lemongrass oils, citronellal in citronella Oil and some eucalyptus oils, benzaldehyde in bitter almond oil, salicylaldehyde in meadow-sweet oil, anisaldehyde in aniseed and fennel oils, cuminaldehyde m cumin oil, cinnamaldehyde in cinnamon oil, carvone in caraway oil, pulegone in pennyroyal oil and methyl nonyl ketone in rue oil The determination of the aldehydes and ketones presents, however, difficulties and the above methods are moderately exact in only a few cases, especially when the content of aldehydes or ketones is considerable The bisulphite method is applicable particularly to the determination of cinnamaldehyde and benzaldehyde in cinnamon oil and bitter almond oil, and, up to a certain pomt, to that of citral in lemongrass Oil. The sulphite method gives good results in the same cases and for the determination of carvone and pulegone... 

The choice of which way round to do the Wittig may appear arbitrary but it isn t. Pempo and his group7 chose citronellal 47 and citronellol 48, two related natural terpenes from citronella oil, as starting materials with the right stereochemistry at the one chiral centre. If you imagine a Wittig reaction between the phosphonium salt 49 and some suitable aldehyde, you will see that the central part of the molecule would be right. 

Citronellal (3,7-dimethyl-6-octenal) Found in essential oils of citronella, eucalyptus citrioda and melissa. Citrus, strong smell very characteristic of citronella. (Fig. 3.8)... 

Limonene (3) a//3-Pinene (4, 5) Linalool (6) Menthol (7) Geraniol (8) Sweet orange (R) Pine wood ((+)-aa, (-)-ff) Ho (R), rosewood ( ) Japanese mint (-) Palmarosa Citronellol (9) Citronellal (10) 1,8-Cineole (1) Citral (11) Eugenol (2) Geranium (S) Eucalyptus (E citriodora, ), citronella (R) Eucalyptus (E globulus) Lemongrass, Litsea cubeba Glove... 

Citronella Cymbopogon winterianus (fi)-Citronellal, geraniol, (fl)-citronellol 95... 

Cymbopogon nardus Rendle (Citronella Leaves SD 0.5 geraniol, citronellal 33,76... 

Derivation From citronellal (Java citronella or Eucalyptus citriodora). 

Synthesis from Citronellal. Citronellal can be hydrogenated to citronellol by the use of special catalysts and/or special hydrogenation techniques, e.g. [47]. The citronellal which is used as starting material may originate from synthetic production or from isolation of essential oils. Citronellal from citronella oil yields (+(-citronellol the corresponding material from citronellal from Eucalyptus citriodora oil is racemic. Pure (+(-citronellol is also obtained from (+)-citronellal which is produced as an intermediate of (-(-menthol (see p. 55-58). By this asymmetric technology, pure (-(-citronellal and therefore pure (-(-citronellol is also available. 

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