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Butyl Group

Butyl Alcohols

Four butyl alcohols exist, each formed by the addition of a hydroxyl group (OH) to one of the four butyl isomers discussed above. Their names and structures are as follows: n-butyl alcohol (or 1-butanol) CH3CH2CH2CH2OH; iso-butyl alcohol (or 2-methyl-1-propanol) (CH3)2CH CH2OH; sec-butyl alcohol (or 2-butanol) CH3CHOHCH2 CH3; tert-butyl alcohol (or 2-methyl-2-propanol) (CH3)3 COH.

The boiling points of the butyl alcohols decrease regularly in moving down the above list, from 244°F (118°C) for n-butyl alcohol to 226°F (108°C) for isobutyl alcohol to 212°F (100°C) for sec-butyl alcohol to 180°F (82°C) for tert-butyl alcohol. A similar pattern exists for solubility of the alcohols, increasing from 8 g per 100 g of water for n-butyl alcohol to 10 g per 100 g of water and 12.5 g per 100 g of water for the next two forms to complete miscibility for tert-butyl alcohol.

The four butyl alcohols undergo very different reactions in many instances. As an example, n-butyl and isobutyl alcohol can be oxidized rather easily to yield aldehydes. Oxidation of sec-butyl alcohol, however, results in the formation of a ketone. Oxidation of tert-butyl alcohol occurs only under the most extreme conditions, resulting in the complete oxidation of the compound to carbon dioxide and water.

Of the four butyl alcohols, n-butyl alcohol is in the greatest demand commercially. It is used as a solvent for fats, waxes, gums, shellac, varnish, and other materials in many industrial processes. It is also used as the starting point in the preparation of other butyl compounds. All of the butyl alcohols are of some interest in the synthetic flavoring industry since they can react with organic acids to make pleasant smelling esters. For example, n-butyl butanoate has the odor of pineapple; 2-methylpropyl propanoate smells like rum; 2-methylpropyl methanoate, like apple; n-butyl methanoate, like banana; and n-butyl ehtanoate, like strawberry.

The accompanying table summarizes some butyl compounds and their most important uses.

Resources

Books

Budavari, Susan, ed. The Merck Index. 11th ed. Rahway, NJ: Merck and Company, 1989. pp. 236-242.

Carey, Francis A. Organic Chemistry. New York: McGraw-Hill, 2002.

Hawley, Gessner G., ed. The Condensed Chemical Dictionary. 9th edition. New York: Van Nostrand Reinhold, 1977, pp. 133-142.

Loudon, G. Mark. Organic Chemistry. Oxford: Oxford University Press, 2002.

KEY TERMS

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Aldehydes

—A class of organic chemical compounds that contain a -CHO group.

Alkyl group

—A paraffinic hydrocarbon group that may be obtained from an alkane by removing a hydrogen atom from the latter.

Antioxidant

—Any substance that prevents oxidation from occurring.

Copolymer

—A compound with high molecular weight formed in the reaction between two different raw materials.

Esters

—A family of organic compounds formed in the reaction between an alcohol and an organic acid.

Food additive

—A substance added to prepared foods to keep them from spoiling, add flavor or odor, increase their nutritional value, or make some other commercially desirable change in the food.

Herbicide

—A chemical that kills entire plants, often selectively.

Inhibitor

—Any substance that prevents some form of chemical reaction from taking place.

Isomers

—Two molecules in which the number of atoms and the types of atoms are identical, but their arrangement in space is different, resulting in different chemical and physical properties.

Ketones

—A family of organic compounds characterized by the presence of the C=O group appearing anywhere except at the end of the molecule.

Polymerization

—A chemical reaction in which small molecules react with each other over and over many times, forming very large product molecules.

Silicone

—A large group of organic compounds whose molecules consist of organic groups attached to silicon atoms.

Additional topics

Science EncyclopediaScience & Philosophy: Boolean algebra to Calcium PropionateButyl Group - Butyl compounds, Butyl alcohols