CHAPTER 12: Unit 1. Definition

Opening Essay

One of the more familiar chemical compounds on Earth is ethyl alcohol (ethanol). As the intoxicant in alcoholic beverages, ethanol is often simply called alcohol. If ethanol is diluted, as it is in wine, beer, or mixed drinks with about 1 oz of liquor, and if it is consumed in small quantities, it is relatively safe. In excess—four or more drinks in a few hours—it causes intoxication, which is characterized by a loss of coordination, nausea and vomiting, and memory blackouts.

Excessive ingestion of ethanol over a long period of time leads to cirrhosis of the liver, alteration of brain cell function, nerve damage, and strong physiological addiction. Alcoholism—an addiction to ethanol—is the most serious drug problem in the United States. Heavy drinking shortens a person’s life span by contributing to diseases of the liver, the cardiovascular system, and virtually every other organ of the body.

In small quantities—one or two drinks a day—ethanol might promote health. In addition to the possible benefits of modest amounts of ethanol, a chemical in red wines, resveratrol, is thought to lower the risk of heart disease. Resveratrol, found in red grapes, is an antioxidant. It inhibits the oxidation of cholesterol and subsequent clogging of the arteries. One need not drink wine to get the benefits of resveratrol, however. It can be obtained by eating the grapes or drinking red grape juice.

Ethanol and resveratrol, a phenol, are representatives of two of the families of oxygen-containing compounds that we consider in this chapter. Two other classes, aldehydes and ketones, are formed by the oxidation of alcohols. Ethers, another class, are made by the dehydration of alcohols.

Here are the structures of two very common alcohols that re used in everyday life.

Definition:  A) Alcohols are organic compounds that contain as -OH group to a saturated carbon atom. The general formula for an alcohol is R-OH, where R is an alkyl group.

Multiple -OH group can be attached to a straight chain compound or a straight chain connected to benzene ring. When two -OH groups are attached toa compound it is called -diol.

B.) Phenols: Phenols have the general formula Ar-OH, where Ar represents an aromatic ( Aryl group) derived from an aromatic compound. Phenols are named as derivatives of the parent compound phenol, using the conventions for an aromatic hydrocarbon nomenclature.

Heterocyclic compound: There is a special class of compound where a hetero atom ( N, O ) are part of the ring ( either aliphatic or aromatic) and they are called heterocyclic compounds.Here are some examples of heterocyclic compounds. Chemistry of heterocyclic compounds are beyond the scope of this course.

C.) Ethers: The general formula for ether is R-O-R’, where R and R’ are alkyl, cycloalkyl or aryl groups. In an IUPAC system, ethers are named as alkoxy derivative of alkanes. Common names are obtained by giving the R group names in alphabetical order and adding the word ether.

Thiols and Disulfides:Thiols are sulfur analog of alcohols. They have the general formula R-SH. The -SH group is called the sulfhydryl group. They are also popularly called mercaptan.  Oxidation of thiols form disulfides, which have the general formula R-S-S-R. The most distinctive physical property of thiols is their foul odor.Thioethers: Thioethers are sulfur analog of ethers. They have the general formula R-S-R.