Geranial citral

In Part A geraniol is oxidized to geranial (citral) by Swern s modification of the Moffat oxidation. 1 The stereoisomerlc purity of the product is at least 98%. This procedure is readily conducted on a large-scale and requires only 4 hours time including distillation of oxalyl chloride. The oxidation of geraniol to pure (E)-geranial may also be accomplished by... 

A great profusion of oxygen-containing isoprenoid compounds are known. Of particular importance in the acyclic series are the alcohols geraniol, nerol, and linalool, and the aldehydes geranial (citral a), neral (citral b), and citronellal ... 

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]... 

E)-Citral (geranial, citral a) and (Z)-citral (neral, citral b) Lemon-like Lemons... 

Both recycled and non-recycled essential oils met the standards for specific gravity, angular rotation and refractive index of the Food Chemicals Codex [22] and United States Pharmacopeia [23] for cold-pressed lemon peel oil. Results of gas chromatography analysis show the same compounds and levels in both systems, specially for the oxygenated compounds as citral (neral and geranial). Therefore, recycling the aqueous discharges to the extractor does not cause undesirable modifications. 

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]. However, lemongrass oil has declined in commercial importance due to the competitive synthesis of citral and isolation of natural citral from Litsea cubeba oil. Today, some lOOt/yr are still... 

Citral is the naturally occurring mixture of the aldehydes geranial 19 and neral 20 (Structure 4.6). Citronellal 21 is another acyclic aldehyde within this grouping. Variation of the 2,6-dimethyloctane skeleton is easily noticeable. 

Citral from ALDRICH was a mixture the E-isomer (geranial) and the Z-isomer (neral), the initial ratio E/Z = 0.51 remained almost constant during hydrogenation, therefore we only referred to the concentration of citral. 

Capric Bomeol Citral geranial Citronellyl Carvone trans- Limonene A-3-Carene ... 

Fig. 8 Monoterpene ketones carvone, geranial, neral, and citronellal together geranial and neral make up citral...

Stahl et al. (4 ) presented solubility data for limonene and caryophyllene with carbon dioxide Gerard ( 3) included carvone. Temperatures in the range of 279 to 377 K, and pressures in the range of 1.5 to 11 MPa were covered. Robey and Sunder (5) provided solubility and relative volatility data for carbon dioxide with concentrated lemon oil and with limonene and citral (geranial/ neral) from 323 to 353 K and 9.4 to 10.6 MPa. 

Figure 5 shows the thermally induced hydrolytic degradation of citral (geranial and neral) into 2-methyl-2-hepten-6-one and acetaldehyde. It is similar to the reaction mechanism as proposed by Josephson and Lindsay (22, 23). The relatively higher amount of 2-methyl-2-hepten-6-one and the concomitant lower amount of geranial and neral in steam distilled oil confirmed again a previous report (24). 

Figure 5. Thermally induced hydrolytic degradation of citral (geranial and citral) into 2-methyl-2-hepten-6-one and acetaldehyde.

Geranial is also called -citral and neral is called -citral. The general name citral is quoted as a constituent of many essential oils such as lemongrass. CitraT is actually a mixture of these c/s and trans isomers. The methyl group, CH3, is always joined by a C C bond to the molecule although, for simplicity, the bond often appears to go to the H atom or the middle of the group. 

Geranial (a-citral trans-3,7-dimethyl-2,6-octadienal) Found in essential oils of lemongrass, lemon, lime, melissa and verbena. Light, sharp, fresh lemon odour. 

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