Higher Unsaturated Alcohol

A typical reaction is the formation of 2-substituted 3,6-divinyltetrahydro-pyranes (108) by the reaction of butadiene with aldehydes (97-100). In this reaction, unsaturated noncyclized alcohols 109 are also formed. The selectivity to the pyranes and alcohols can be controlled by the ratio of Pd and PPh3 in the catalyst system. When the ratio was higher than 3, pyranes were formed exclusively. On the other hand, with the lower ratio of Pd and PPh3, the unsaturated alcohols were formed as the main product. 

V.C.8.1. Alkenes and Alcohol Functions. Although TS-1 and other titanosi-licates oxidize alcohols to the corresponding aldehydes and ketones, the rates are suppressed in the presence of compounds containing C=C bonds. CH3OH, for example, is not oxidized at all during epoxidations of alkene reactants. Higher alcohols, however, are partially oxidized. The oxidation of unsaturated alcohols in the presence of TS-1 is shown in Table XVII (193). 

Phenethyl alcohol is qualitatively and quantitatively one of the most important fragrance substances that belongs to the class of araliphatic alcohols. Its lower homologue (benzyl alcohol) and higher homologue (dihydrocinnamic alcohol) also have characteristic odor properties, but are more frequently used in the form of their esters. Cinnamic alcohol, the most important unsaturated araliphatic alcohol, is valuable for both fragrances and flavors. 

Salts of the hydrogen sulphate esters of these higher alcohols are used extensively in the textile industries, those of the unsaturated alcohols possessing superior properties in certain respects. 

Fatty alcohols are obtained by direct hydrogenation of fatty acids or by hydrogenation of fatty acid esters. Typically, this is performed over copper catalysts at elevated temperature (170°C-270°C) and pressure (40-300 bar hydrogen) [26], By this route, completely saturated fatty alcohols are produced. In the past, unsaturated fatty alcohols were produced via hydrolysis of whale oil (a natural wax occurring in whale blubber) or by reduction of waxes with sodium (Bouveault-Blanc reduction). Today, they can be obtained by selective hydrogenation at even higher temperatures (250°C-280°C), but lower pressure up to 25 bar over metal oxides (zinc oxide, chromium oxide, iron oxide, or cadmium oxide) or partially deactivated copper chromite catalysts [26],... 

The reaction may proceed as homo- or cross-dehydrodimerization [105] and takes place with a wide range of substituted substrates such as higher alcohols, ethers, silanes, and partially fluorinated alcohols and ethers, but also with ketones, carboxylic acids, esters, amides, and amines [106]. Besides the formation of 1,2-diols from saturated alcohols, unsaturated substrates are also dimerized under hydrogen to form l,n-diols other than the 1,2-isomers [107]. The regio-selectivity of the diols is controlled by the formation of the most stable radical, which then dimerizes. 

The fatty acids are then separated into saturated and unsaturated forms. The fatty acids then can be hydrogenated to form fatty alcohols. The same catalyst used to reduce the unsaturation can be used to form the fatty alcohols. Similar temperatures are used with an increased hydrogen pressure (2.5 Mpa). Fatty alcohols have the same use as higher alcohols and are discussed in the higher alcohols section. 

These are saturated or unsaturated alcohols containing one hydroxyl group (primary). Ce—Ci2 alcohols are sparingly soluble in water their solubility decreases with carbon chain length. Higher alcohols are insoluble in water. All the compounds are miscible with ethanol, petroleum ether, and many other organic solvents. 

Mittasch and Schneider. The first patent for the synthesis of methanol was granted in Germany to Mittasch and Schneider in 1913 (1 ). The catalysts which they described were oxides of cerium, chromium, manganese, molybdenum, titanium, and zinc which had been "activated" by incorporating alkalies such as sodium and potassium carbonates. The products were methanol, higher alcohols and saturated and unsaturated hydrocarbons. Pressures and temperatures were 100-200 atmospheres and 300 to 400 C. These were... 

Fischer and Tropsch. The next patent was issued to Fischer and Tropsch and was granted in 1922 (2), 9 years after the Mittasch-Schneider patent. The catalysts which were claimed by Fischer and Tropsch were elemental nickel, silver, copper and iron and most specifically iron plus cesium and rubidium-hydroxides. The products of the Fischer-Tropsch catalysts at that time were methanol, higher alcohols, other oxygenated products but no hydrocarbons either saturated or unsaturated. The name that was assigned to this product was "synthol. Fischer and Tropsch used a slightly higher temperature (420 C) and pressure (134 atm.) than Mittasch and Schneider employed. 

Sperm oil occurs in the blubber and in the head cavities of the sperm whale (this cavity helps the whale keep part of his head above water to breathe). The oil contains a solid fraction (spermaceti, cetin, cetylpalmitate) which can be cristallised.The liquid fraction mainly contains oleyloleate and higher mono-unsaturated fatty acid monesters of unsaturated fatty alcohol. 

The commercial exploitation of sperm oil has led to the depletion of whale populations and is banned in some countries. Attention has, therefore, turned to the jojoba plant whose oil also consists of wax esters. Most fatty chemicals obtained from natural sources have chain lengths of Cig-Cig. The limited availability of compounds with 12-14 carbon atoms, which are important in surfactants, was one of the driving forces behind the development of petrochemical processes for the production of fatty alcohols. Higher alcohols, such as C20-C22 alcohols, can be produced from rapeseed oils rich in erucic acid and fish oils. Unsaturated fatty alcohols may be manufactured in the presence of selective catalysts. 

The alcohols above ethyl in the series are generally spoken of as higher alcohols. An extensive literature on their presence in brandy has developed because of their importance to the organoleptic character of brandy. Much less information is available for wines. The chief higher alcohols found are isoamyl (3-methyl-l-butanol), active amyl ((—)-2-methyl-l-butanol), -propyl (1-propanol), isobutyl (2-methyl-l-propa-nol), n-butyl (1-butanol), and (—) sec-butyl (2-butanol). Others doubtless occur and will be identified as better methods for their separation are developed. Buscarfins (1941) fractionated (under vacuum) a fusel oil from wine pomace and identified amyl, propyl, isobutyl, butyl, and isopropyl (2-propanol)alcohols as esters and higher alcohols up to decyl. No hi er secondary alcohols were found. The residue consisted of esters, fatty acids, furfural, cylic bases, and hydrocarbons. Only acids with an even number of carbon atoms were demonstrated. The unsaturated acids oleic and linoleic were present in small amounts, presumably from the seeds. Ethyl esters were more important in amount than amyl esters. There was 3% furfural, 5.5% fatty acids (free and esterified), 30.9% alcohols (free and esterified), and 1.6% hydrocarbons (terpene). Dupont and Dulou (1935) demonstrated sec-butyl alcohol in a technical propyl alcohol that had been produced from fusel oil. 

Among the higher aldehydes ( )-2-tridecenal is responsible for the bug-like odor note in coriander seed oil (Coriandrum sativum L.) (545). In addition, ( )-2-dodecenal and ( )-2-decenal, together with the saturated members with 9 to 12 carbon atoms, were found in the same essential oil (626). It should be pointed out that the oil of coriander leaves, widely employed as a flavoring commodity in certain Eastern dishes consists of nearly 90% of aliphatic aldehydes (370). As is well known, quite a number of simple long-chain unsaturated aldehydes, alcohols and esters act as pheromones in various insects (41). 

Unsaturated azlactones ordinarily do not react readily with hot alcohols. However, if either an acid > or a base is added to the ethanol, the oxazolone ring is opened rapidly with the formation of an a-acyl-aminoacrylic ester. With sodium hydroxide or alkoxide the reaction is complete in three to five minutes at room temperature. > With sodium carbonate as catalyst a short period of refluxing is required. Azlactones also react rajadly with higher alcohols in the presence of the sodium alkoxide. ... 

The alicyclic secondary alcohol, cycZohexanol, may be dehydrated by concentrated sulphuric acid or by 85 per cent, phosphoric acid to cyciohexene. It has a higher boiling point (82-83°) than amylene and therefore possesses some advantage over the latter in.the study of the reactions of unsaturated hydrocarbons. 

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