Natural alcohols

ALCOHOLS,HIGHERALIPHATIC - SURVEY AND NATURAL ALCOHOLS MANUFACTURE] (Vol 4)... 

Survey and natural alcohols manufacture, Synthetic processes,... 

Eats and oils from a number of animal and vegetable sources are the feedstocks for the manufacture of natural higher alcohols. These materials consist of triglycerides glycerol esterified with three moles of a fatty acid. The alcohol is manufactured by reduction of the fatty acid functional group. A small amount of natural alcohol is also obtained commercially by saponification of natural wax esters of the higher alcohols, such as wool grease. 

Up till about three years ago, there appeared to be little reason to doubt that rhodinol was in fact an impure form of citronellol, the reduction product of citroneUal being dextro-citronellol, whilst the natural alcohol, which the French chemists had termed rhodinol was considered to be laevo-citronellol. 

It can be obtained artificially by treating sabinene or thujene with dilute sulphuric acid, when the resulting alcohol is optically inactive. The natural alcohol, isolated from juniper berry oil, has the following characters —... 

This helps explain why a wine should be left to stand some of the natural alcohols in the wine are oxidized by oxygen dissolved from the air to form carboxylic acids. These acids then react with the natural alcohols to generate a wide range of esters, which connoisseurs of wines will recognize as a superior taste and bouquet . 

Oleochemical alcohols, sometimes known as natural alcohols, are also identified by the carbon range C12-C14 lauric, Ci6-Ci8 tallow, regardless of the origin of the raw material. C1(-i-C18 alcohols were predominantly produced in the past from tallow, hence their name, although today they are also widely produced from palm oil. Lauric range alcohols are produced from either coconut oil or from palm kernel oil. 

The Oxo alcohols contain one more carbon atom chan the original olefin used. They differ in two respects from the natural alcohols. First the Oxo alcohols contain either even or odd numbers of carbon atoms, the natural alcohols only even. Second, the Oxo alcohols all have some branched molecules—originally about 40% but with recent process improvements, as low as 5%. See Figure 15—4.)... 

The chiral alcohol, 2-methyl-4-octanol, was identified as an aggregation pheromone from airborne volatiles produced by male and females of the sugarcane weevil Sphenophorus levis. Enantiomeric resolution by GC with a chiral column showed that the natural alcohol possessed the S configuration. The alcohol elicited aggregation behavior among adults. ... 

Fig. 23.1 Microbial routes from natural raw materials to and between natural flavour compounds (solid arrows). Natural raw materials are depicted within the ellipse. Raw material fractions are derived from their natural sources by conventional means, such as extraction and hydrolysis (dotted arrows). De novo indicates flavour compounds which arise from microbial cultures by de novo biosynthesis (e.g. on glucose or other carbon sources) and not by biotransformation of an externally added precursor. It should be noted that there are many more flavour compounds accessible by biocatalysis using free enzymes which are not described in this chapter, especially flavour esters by esterification of natural alcohols (e.g. aliphatic or terpene alcohols) with natural acids by free lipases. For the sake of completeness, the C6 aldehydes are also shown although only the formation of the corresponding alcohols involves microbial cells as catalysts. The list of flavour compounds shown is not intended to be all-embracing but focuses on the examples discussed in this chapter... 

These natural acids synthesised from natural alcohols have market prices of less than 100 per kilogram and are of great importance to the flavour industry either because of their intense smell and sour taste or as substrates for enzymatic... 

Scheme 23.1 a Short-chain flavour acid production from natural alcohols by acetic acid bacteria b Jasmonic acid and methyl jasmonate production with Diploida gossypina... 

Scheme 23.2 Production of aliphatic flavour aldehydes from natural alcohols using alcohol oxidase activity of Pichia pastoris cells...

Nevertheless, for the production of the flavour-active aromatic alcohol derivatives, such as the corresponding aldehydes and acids, metabolic engineering approaches have to compete with conventional oxidative biocatalysis starting from the natural alcohol as a substrate. For instance, the whole-cell oxidation system based on Pichia pastor is AOX already described in Sect. 23.4.1.2 can also be used to convert benzyl alcohol to benzaldehyde in aqueous media although product inhibition restricted the final product concentration to about 5 g L h indicating the need for aqueous-organic two-phase reaction media [51]. Phenylacetalde-... 

A process based on the use of an immobilized C. antarctica lipase (Novozym 435) has been developed in order to perform direct esterification of natural alcohols with carboxylic acids in a solvent-free system. Based on the system represented in Figure 11.2, the process had to overcome the problem of recycling the nitrogen, once the reaction was over. 

The mingling of inferior wines with superior, or with brandy, is not the sophistication for which the chemical professor is so much required to confer a boon upon the public, as in detecting extraneous substances of no vioous obaracter at all. To brandy intermixed with wine, and which never blends with it as the natural alcohol ofthe wine does, are owing, in many cases, the liver complaints of the wine drinkers in England—-a disease rare in wine countries. 

---