Sources of Alcohols

At one time, the major source of methanol was as a byproduct in the production of charcoal from wood—hence, the name wood alcohol Now, most of the more than 10 billion lb of methanol used annually in the United States is synthetic, prepared by reduction of carbon monoxide with hydrogen. Carbon monoxide is normally made from methane. 

The major uses of methanol are in the preparation of formaldehyde and tert-hwiy methyl ether (known commercially as MTBE). Formaldehyde is a starting material for various resins and plastics, including the first completely synthetic plastic Bakelite. MTBE is an effective gasoline additive, but problems with it leaking from underground tanks and contaminating groundwater make it unsuitable for continued use. 

Some of the substances used to denature ethanol include methanol, benzene, pyridine, castor oil, and gasoline. 

Recall from Section 2.19 that reduction corresponds to a decrease in the number of bonds between carbon and oxygen or an increase in the number of bonds between carbon and hydrogen (or both). 

Methanol is a colorless liquid, boiling at 65°C, and is miscible with water in all proportions. It is poisonous drinking as little as 30 mL has been fatal. Smaller amounts can produce blindness. 

The major use of methanol is in the preparation of formaldehyde as a starting material for various resins and plastics. 

Synthetic ethanol and isopropyl alcohol are derived from petroleum by hydration of 

2-Phenylethanol is part of the fragrant oil of many flowers including rose and hyacinth. 

3-Hydroxy-4-phenylbutan-2-one is a fragrant component of wisteria flowers. 

Carbon monoxide is obtained from coal, and hydrogen is one of the products formed when natural gas is converted to ethylene and propene (Section 5.1). 

Almost half of this methanol is converted to formaldehyde as a starting material for various resins and plastics. Methanol is also used as a solvent, as an antifreeze, and as a convenient clean-burning liquid fuel. This last property makes it a candidate as a fuel for automobiles— methanol is already used to power Indianapolis-class race cars— but extensive emissions tests remain to be done before it can be approved as a gasoline substitute. Methanol is a colorless liquid, boiling at 65°C, and is miscible with water in all proportions. It is poisonous drinking as little as 30 mL has been fatal. Ingestion of sublethal amounts can lead to blindness. 

When vegetable matter ferments, its carbohydrates are converted to ethanol and carbon dioxide by enzymes present in yeast. Fermentation of barley produces beer grapes give wine. The maximum ethanol content is on the order of 15%, because higher concentrations inactivate the enzymes, halting fermentation. Since ethanol boils at 78°C 

Synthetic ethanol is derived from petrolenm by hydration of ethylene. In the United States, some 700 million lb of synthetic ethanol is prodnced aimnaUy. It is relatively inexpensive and usefnl for industrial applications. To make it unlit for drinking, it is denatured by adding any of a number of noxious materials, a process that exempts it from the high taxes most governments impose on ethanol used in beverages. 

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The dihydroxyacetone side chain is conveniently protected by forming 17a,20 20,21-bismethylenedioxy compounds (BMD) (92). Formation of llf -ethers as by-products from 11 -hydroxycompounds (91) can be limited by using formalin with a low methanol content, or better with paraformaldehyde as a source of alcohol-free formaldehyde. ... 

The source of alcohol 50 is most probably acid-catalysed hydrolysis of 49 to the nitrosocarbonylbenzene intermediates 51, which, like acid chlorides, react with water to give benzoic acids 52 (Scheme 1 pathway (i)).159 Acylnitroso intermediates 51 were trapped as the Diels Alder adducts 53 in reactions in CH3CN/H20 and in the presence of cyclopentadiene. In CH3CN/10% H280, 53 was enriched in lsO... 

Methanol or methyl alcohol can become an alcoholic s main source of alcohol because it is cheaper. Methanol is frequently used as an additive for industrial ethanol to circumvent taxes. Methanol may be purposely adulterated to make it less palatable, but it is used nevertheless Methanol ingestion can be fatal due to its CNS depressant effects. In addition it is toxic because it is a substrate for alcohol dehydrogenase forming formic acid and formaldehyde which... 

The equation shows that alcohol in the form of ethanol reacts with an orange solution of potassium dichromate to produce a green solution of chromic sulfate. The source of alcohol is the suspect s breath. More alcohol produces a greater color change. The breath analyzer measures this color change and coverts this measurement into an amount of alcohol in the blood. 

The production of cheap dessert wines during the depression years also had another unfortunate result dessert wines were the cheapest source of alcohol. The skid-row alcoholic used wine as his source of alcohol and became known as a wino. ... 

We have already mentioned that one of the factors that makes acyclic ftemiacetals unstable is the unfavourable decrease in entropy when two molecules of starting material (aldehyde or ketone plus alcohol) become one of product. The same is true for acetal formation, when three molecules of starting material (aldehyde or ketone plus 2 x alcohol) become two of product (acetal plus H2O). We can improve matters if we tie the two alcohol molecules together in a diol and make a cyclic acetal we discuss cyclic acetals in the next section. Alternatively, we can use an orthoester as a source of alcohol. Orthoesters can be viewed as the acetals of esters or as the triesters of the unknown orthoacids —the hydrates of carboxylic acids. They are hydrolysed by water, catalysed by acid, to ester + 2 x alcohol. 

Natural sources of sugar available to primitive people were fruit and honey, both of which can be made into wine with a maximum alcohol content of about 12 percent. Starch is also a potential source of alcohol, but it must be converted to sugar by enzymes before yeast can digest it. There are enzymes in saliva that can accomplish this, and one of the earliest kinds of hecr was made by Indians in tropical America who learned to chew corn to a pulp, spit it into clay pots, mix it with water, and let it ferment. Sprouting grains also produce usable enzymeS in standard beermaking, sprouted barley (malt) is used to convert the starcli of... 

A source of alcohol and alcoholic beverages. The starch of grains, potatoes, etc., is first hydrolyzed by natural sprouting, as in the preparation of barley malt, or by the addition of malt to it. The hydrolytic products, glucose and maltose, are then fermented by the addition of yeast, containing the enzymes, maltase, and zymase, and alcohol is thus produced. This has been fully discussed in the chapter on alcoholic fermentation, (p. 95). 

We have seen (Sec. 18.5) that in the carboxylic acids obtained from fats we have available long straight-chain units for. .se in organic synthesis. Reduction of these acids to alcohols (either directly or as esters) is a fundamental step in the utilization of these raw materials, since from the alcohols, as we know, a host of other compounds can be prepared (Sec. 16.10). Although only acids of even carbon number are available, it is possible, of course, to increase the chain length and thus prepare compounds of odd carbon number. (For an alternative source of alcohols both of even and odd carbon number, see Sec. 32.6.)... 

Today, the decision for a suitable source of alcohol for low-alcoholic beverages is often based more on tax savings and cost efficiency of the source of alcohol than on the raw material nature of the alcohol base. 

If molasses or beet mots arc used a , the source of alcohol, maltiiii, is iinnecessary, a solution of the niatciial is pH pared to conlaiii a suitabh- pro])ortiou of sny.at fermented... 

Cereals and potatoes are, however, a staple article of food, and unless cultivation is enormously increased, this source of alcohol production will remain too expensive for the production of industrial spirit. 

Cleanliness is necessary, not only because dirt is not a source of alcohol, but because it is sure to carry large numbers of bacteria and molds, which interfere with the production of a good malt. 

The concentrated alcohol-water vapor of 80-95 percent is then condensed to liquid in the condenser by cooling it. Roughly 2/3 to 3/4 of the final liquid is returned to the rectifying section of the still as "reflux" (a liquid of high alcohol concentration). It provides a highly volatile source of alcohol vapor to facilitate a high final-product concentration and to condense out some of the remaining water vapor. This reflux is necessary to obtain a concentrated alcohol product. 

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