Alcohols, primary examples

The above simple process cannot be applied to the preparation of the homo-logues a higher temperature is requir (di-n-amyl ether, for example, boils at 169°) and, under these conditions, alkene formation predominates, leading ultimately to carbonisation and the production of sulphur dioxide. If, however, the water is largely removed by means of a special device (see Fig. Ill, 57,1) as soon as it is formed, good 300 of ethers may be obtained from primary alcohols, for example ... 

The butanols undergo the typical reactions of the simple lower chain aUphatic alcohols. For example, passing the alcohols over various dehydration catalysts at elevated temperatures yields the corresponding butenes. The ease of dehydration increases from primary to tertiary alcohol /-butyl alcohol undergoes dehydration with dilute sulfuric acid at low temperatures in the Hquid phase whereas the other butanols require substantially more stringent conditions. 

Each R represents an organic group, such as methyl or ethyl. They need not all be the same. Ethanol is a primary alcohol and 2-butanol is a secondary alcohol. An example of a tertiary alcohol is 2-methyl-2-propanol, (CH3)3COH. 

Acids can be produced by the oxidation of aldehydes or primary alcohols. For example, the souring of wine results from the oxidation of the ethyl alcohol in wine to acetic acid ... 

The determination of enantiomeric excess (96% ee) of the Claisen rearrangement products 4a and 4b is accomplished by a Mosher 1H NMR analysis of the (R)-O-acetylmandelate esters that are derived from the primary alcohols. For example, 4a is reduced with UAIH4 (1.0 equiv/THF/0°C) followed by esterification of the resulting primary alcohol with (R)-O-acetylmandelic acid (DCC, 1.5 equiv/cat. DMAP/CH2CI2) to afford the mandelate ester in 91% yield (two steps).3... 

In 1992, Hari Prasad Rao and Ramaswamy reported on the oxyfunctionalization of alkanes with H2O2 using a vanadium silicate molecular sieve s . With this catalyst acyclic and cyclic alkanes were oxidized to a mixture of the corresponding alcohols (primary and secondary ones), aldehydes and ketones. Unfortunately, most of the early attempts were of rather limited success due to low turnover frequencies and radical producing side reactions as observed, for example, by Mansuy and coworkers in 1988. ... 

We have also carried out experiments in secondary alcohols. For example. Fig. 5 shows the spectra in primary and secondary octanol (1-octanol vs. 2-octanol). These data show that while the initial spectra are approximately the same in the two alcohols, the final spectra are considerably different. There is much less shift in the absorption spectrum in the 2-octanol, suggesting that 2-octanol is less effective at solvating the benzophenone molecule. 

Aliphatic hydroxylation. As well as unsaturated aliphatic compounds such as vinyl chloride mentioned above, which are metabolized by epoxidation, saturated aliphatic compounds also undergo oxidation. The initial products will be primary and secondary alcohols. For example, the solvent n-hexane is known to be metabolized to the secondary alcohol hexan-2-ol and then further to hexane-2,5-dione (Fig. 4.9) in occupationally exposed humans. The latter metabolite is believed to be responsible for the neuropathy caused by the solvent. Other toxicologically important examples are the nephrotoxic petrol constituents, 2,2,4- and 2,3,4-trimethylpentane, which are hydroxylated to... 

A number of contradictory views have been published concerning the structure of adsorbed alcohols and the nature of adsorption sites (for review see ref. 69). Experimental evidence from IR investigations has shown that, on alumina, alcohols form several surface complexes of very different chemical natures (e.g. refs. 31, 32, 117, 133—137) (i) alcohol molecules weakly bonded to the surface, very probably by hydrogen bonds (I) (such complexes are sometimes denoted as physically sorbed alcohols) (ii) surface alkoxides (alcoholates) (II) (iii) surface carboxy-lates (III). Less certain is the existence of species with partial double bonds or of ketone-like species. The formation of the various surface complexes is dependent on the structure of the alcohol. For examples, weakly bonded species (I) have been found with all alcohols, alkoxides (II) mostly with primary alcohols, sometimes also with secondary alcohols, but have never been reported for tertiary alcohols. 

Unlike the alcohol in Example 7.2, the alcohol in this case is primary instead of tertiary. The rate-determining step is the SN2 reaction ... 

Analytical Properties Separation of primary a-amino alcohols, for example, p-hydroxyphenethylamines and... 

Subsequently, in 1999 the same group showed that the activity of the ruthenium hydrotalcite was significantly enhanced by the introduction of cobalt(II), in addition to ruthenium(III),in the Brucite layer [115]. For example, cinnamyl alcohol underwent complete conversion in 40 min in toluene at 60 °C, in the presence of ruthenium/cobalt hydrotalcite, compared with 31% conversion under the same conditions with ruthenium hydrotalcite. A secondary aliphatic alcohol, 2-octanol, was smoothly converted into the corresponding ketone but primary aliphatic alcohols, for example, 1-octanol, exhibited extremely low activity. The authors suggested that the introduction of cobalt induced the formation of higher oxidation states of ruthenium, for example, Ru(IV) to Ru( VI), leading to a more active oxidation catalyst. However, on the basis of the reported results it is not possible to rule out low-valent ruthenium species as the active catalyst in a hydridometal pathway. The results obtained in the oxidation of representative alcohols with ruthenium hydrotalcite and ruthe-nium-cobalt-hydrotalcite are compared in Table 5. 

Sugar esters differ from ethers by being readily hydrolyzed by alkali. Methods for the esterification of polyhydroxy compounds do not generally differ from those applicable for the esterification of simple alcohols. Primary hydroxyls may in certain cases be esterified selectively, since they are more reactive than the secondary hydroxyls. Sometimes a partial esterification of the hydroxyls is desirable. The preparation of esters is clarified by examples collected in Fig. 2-21. 

In a brief communication, it was reported that quinolinium chlorochromate is a selective oxidant for primary alcohols for example, this reagent is reported to oxidize the diol (11) selectively to the aldehyde (12 equation 12). 

Aldehydes and ketones are most often produced commercially by the oxidation of alcohols. For example, oxidation of a primary alcohol yields the corresponding aldehyde ... 

Urethanes. The reagent (I) reacts with primary alcohols, for example 1-hexanol (2), to form the salt (3), which when heated at 95° for 1 hr. and then treated with water is converted into methyl-N-hexylcarbamate (4) in 55 % yield. Benzyl alcohol is converted in Ihc same way into methyl-N-bcnzylcarbamate (80% yield). 

Plant waxes are usually found on leaves or seeds. Thus, cabbage leaf wax consists of the primary alcohols C12 and Cis—C28 esterified with palmitic acid and other acids. The dominant components are stearyl and ceryl alcohol (C26H53OH). In addition to primary alcohols, esters of secondary alcohols, for example, esters of nonacosane-15-ol, are present ... 

Enzyme-mediated carbonyl reductions are not restricted to aldehydes and ketones. With some organisms, carboxy groups can be reduced to primary alcohols. The example in Scheme 53 proceeds with enantiomeric specificity, ... 

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