Oleic aldehyde

Oleic Aldehyde.—Oleic aldehyde, CjjH33.CHO, is -found in oil of orris root. It bas the following characters —... 

Orris Root Oil. Cottsiit. About 85% myristic acid the odorous pinciple irone methyl myristate, oleic aldehyde,... 

Schimmel Oo. have isolated from the oil furfurol a terpene which was not identified (specific gravity 0 861 rotation h- 10 40 ) decyl aldeyde nonyl aldehyde naphthalene (a very rare constituent of essential oils) and a ketone of the formula OjoH igO. They do not agree with Tiemann and Kruger that oleic aldehyde is present in the oil. 

Examples are given of common operations such as absorption of ammonia to make fertihzers and of carbon dioxide to make soda ash. Also of recoveiy of phosphine from offgases of phosphorous plants recoveiy of HE oxidation, halogenation, and hydrogenation of various organics hydration of olefins to alcohols oxo reaction for higher aldehydes and alcohols ozonolysis of oleic acid absorption of carbon monoxide to make sodium formate alkylation of acetic acid with isobutylene to make teti-h ty acetate, absorption of olefins to make various products HCl and HBr plus higher alcohols to make alkyl hahdes and so on. 

Fig. 15.48. Decomposition of the asymmetric primary ozonide formed in the ozonolysis of oleic acid. Two different aldehydes and two different carbonyl oxides are formed. In CH2Cl2 these molecules react with each other to form three secondary ozonides. In methanol, on the other hand, the carbonyl oxides react with the solvent to form hydroperoxides.

As indicated, a variety of aldehydes have been demonstrated in oxidized fats. Alcohols have also been identified, but the presence of ketones is not as certain. Keeney (1962) has listed the aldehydes that may be formed from breakdown of hydroperoxides of oxidized oleic, linoleic, Iinolenic, and arachidonic acids (Table 2-23). The aldehydes are powerful flavor compounds and have very low flavor thresholds for example, 2,4-decadie-nal has a flavor threshold of less than one part per billion. The presence of a double bond in an aldehyde generally lowers the flavor threshold considerably. The aldehydes can be further oxidized to carboxylic acids or other tertiary oxidation products. 

On an industrial scale, the traditional method for cleavage of carbon-carbon double bonds is ozonolysis, used for the manufacture of azelaic acid and nonanoic acids from oleic acid, and of butane tetracarboxylic acid from tetrahydrophthalic anhydride. The process is effectively a quantitative and mild process.178 However, it is capital and energy intensive. The intermediate ozonide is worked up either reductively or oxidatively to produce the aldehyde, ketone or carboxylic acid. Hydrogen peroxide is the common oxidizing agent used in the second step.179-181 Oxygen can also be used either alone182 or in combination with zeolites.183 Reviews on ozonolysis are available and the reader is directed to reference 184 for further information. 

Anisidine Value. Anisidine value is a measure of secondary oxidation or the past history of an oil. It is useful in determining the quahty of crude oils and the efficiency of processing procedures, but it is not suitable for the detection of oil oxidation or the evaluation of an oil that has been hydrogenated. AOCS Method Cd 18-90 has been standardized for anisidine value analysis (103). The analysis is based on the color reaction of anisidine and unsaturated aldehydes. An anisidine value of less than ten has been recommended for oils upon receipt and after processing (94). Inherent Oxidative Stability. The unsaturated fatty acids in all fats and oils are subject to oxidation, a chemical reaction that occurs with exposure to air. The eventual result is the development of an objectionable flavor and odor. The double bonds contained in the unsaturated fatty acids are the sites of this chemical activity. An oil s oxidation rate is roughly proportional to the degree of unsaturation for example, linolenic fatty acid (C18 3), with three double bonds, is more susceptible to oxidation than linoleic (C18 2), with only two double bonds, but it is ten times as susceptible as oleic (C18 l), with only one double bond. The relative reaction rates with oxygen for the three most prevelent unsaturated fatty acids in edible oils are ... 

Since 1951, the ozonolysis of oleic acid (I) from sperm oil has been studied in this laboratory good yields of nonyl aldehyde (II), nonanoic acid (III), and azelaic acid (V) have been obtained. 

These studies showed that azelaic half aldehyde (IV), an intermediate product, is usually obtained in some quantity by decomposition of oleic acid ozonide. Reductive decomposition of the ozonide was then tried to preserve both aldehyde groups. Sodium sulfite as the reducing agent gave the first successful result. Azelaic half aldoxime (VI) could then be easily obtained from azelaic half aldehyde (IV) and hydroxylamine. Finally, co-aminononanoic acid (VII) was obtained by neutral reduction of azelaic half aldoxime (VI). 

Hydrogenation. Carboxylic acids are reduced to aldehydes by hydrogen in the presence of (PhjPl Pd and pivalic anhydride. Alkenoic acids (oleic acid, erucic acid) give unsaturated aldehydes. Diacids are similarly reduced. 

The most important precursors for lipid oxidation are unsaturated fats and fatty acids like oleic (18 1), linoleic (18 2), linolenic (18 3) and arachidonic acid (20 4). The more unsaturated ones are more prone to oxidation. Lipid peroxidation and the subsequent reactions generate a variety of volatile compounds, many of which are odour-active, especially the aldehydes. That is why lipid oxidation is also a major mechanism for thermal aroma generation and contributes in a great measure to the flavour of fat-containing food. Lipid oxidation also takes place under storage conditions and excessive peroxidation is responsible for negative aroma changes of food like rancidity, warmed-over flavour, cardboard odour and metallic off-notes. 

Derivation By the oxidation of nonyl alcohol or nonyl aldehyde by the oxidation of oleic acid, especially by ozone. 

Saturated and unsaturated aldehydes with chain lengths C5-C11 are some of the most problematic and undesirable substances in indoor rooms. Aliphatic aldehydes are very odour-intensive, and the odour is generally described as unpleasantly rancid or greasy . With sensitive persons or in high concentrations the perception of ahphatic aldehydes can cause nausea. Odour thresholds are, for example, 57 and 13 pg m [77] for hexanal and nonanal, and the odour thresholds of the imsaturated aliphatic aldehydes are even a magnitude smaller. Emission sources in indoor rooms are essentially unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid as components of... 

Lipid-derived volatile compoimds dominate the flavor profile of pork cooked at temperatures below 100°C. The large numbers of heterocyclic compounds reported in the aroma volatiles of pork are associated with roasted meat rather than boiled meat where the temperature does not exceed 100 C (34,35). Of flie volatiles produced by lipid oxidation, aldehydes are the most significant flavor compounds (35,36). Octanal, nonanal, and 2-undecenal are oxidation products from oleic acid, and hexanal, 2-nonenal, and 2,4-decadienal are major volatile oxidation products of linoleic acid. 

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