Monohydric Alcohols—C₇to C₁₈, Aromatic, and Other Alcohols

Abstract

This chapter reviews linear and branched C 7 to C 18 monohydric aliphatic alcohols, as well as aromatic, alicyclic, aliphatic unsaturated, and aliphatic halogenated alcohols. The CAS registry number and molecular structures have been provided for all the alcohols, except for the oxo alcohols. These alcohols are mixtures of isomeric alcohols with the same molecular formula, with the composition and CAS registry number dependent on the olefin feedstock. The physical and chemical properties for these alcohols are listed. The National Fire Protection Association (NFPA) has prepared a rating system to assess the physical and chemical hazards of chemicals with respect to flammability, health, and reactivity. In general, these alcohols are not reactive chemicals, except for the unsaturated alcohols. The most important commercial member of the heptanols is isoheptyl alcohol, which is a mixture of branched C 7 alcohols. This alcohol is used for the manufacture of esters such as phthalate plasticizers. 1‐Heptanol has little commercial value. Other C 7 alcohols are 2,3‐dimethyl‐1‐pentanol and the secondary alcohols, 2‐heptanol, 3‐heptanol, 4‐heptanol, and 2,4‐dimethyl‐3‐pentanol. 2‐Heptanol and 3‐heptanol can exist as enantiomers. The available toxicity data indicate that heptanols have a low order of acute toxicity and no occupational exposure standards exist for them. The most important commercial C 8 alcohols are 2‐ethylhexanol and a mixture of branched C 8 alcohols referred to as isooctyl alcohol. Other octanols of lesser commercial interest are 2‐octanol, 1‐octanol, 3,5‐dimethyl‐1‐hexanol, 2,2,4‐trimethyl‐1‐pentanol, and 2‐ethyl‐4‐methyl‐1‐pentanol. These alcohols are liquids at ambient temperature and used primarily in producing esters, such as plasticizers. No occupational exposure standards exist for octanols except for isooctyl alcohol. The most important commercial members of this subgroup of alcohols are the C 9 oxo alcohols, which are a mixture of predominantly C 9 branched alcohols, diisobutyl carbinol, and 2,6‐dimethyl‐4‐heptanol. Two C 9 alcohols of lesser commercial importance are 1‐nonanol and 3,5,5‐trimethyl‐1‐hexanol. All these alcohols are liquids at ambient temperatures. Acute studies in animals indicate a low order of toxicity. These alcohols are irritating to the skin, eyes, and respiratory tract. They are also aspiration hazards. No serious adverse effects from industrial exposure were reported in humans. Prolonged or excessive exposure to the alcohols can produce local irritation and narcosis. No occupational exposure standards have been established for any of the nonanols. The decanols consist of more than 20 structural isomers, including a number of enantiomers. The most important commercial members are the C 10 oxo alcohols, which exist as a mixture of branched C 10 alcohols. Many of these alcohols are liquids. Unlike the lower alcohols, decanols are less volatile and flammable. Toxicity studies indicate that these alcohols have a low order of acute toxicity, but they are irritating to both skin and eyes. No serious industrial intoxication has been reported for the decanols. No occupational exposure standards exist for the decanols. Dodecanols consist of more than 20 structural isomers, including a number of enantiomers. The two most prominent members of this group of alcohols are 1‐dodecanol and isodecyl alcohol, a mixture of predominantly C 12 branched alcohols. Toxicity studies indicate that dodecanols have a low order of acute toxicity. 1‐Dodecanol is the most studied C 12 alcohol and is a tumor promoter in mice. There have been no reports of adverse effects in humans. No occupational exposure standards have been established for any of the decanols. There are at least five aromatic alcohols of commercial interest: three primary alcohols (benzyl alcohol, 2‐phenylethanol, and p ‐tolyl alcohol) and two secondary alcohols (1‐phenylethanol and 2‐phenyl‐2‐propanol). All these alcohols are liquids at ambient temperatures. No valid NIOSH methods exist to measure these alcohols in air. The toxicities of benzyl alcohol and 2‐phenylethanol are the most studied of the aromatic alcohols. As a group, these alcohols have a low to moderate order of acute toxicity and have been both active and inactive in genotoxicity assays. No occupational exposure standards have been set for these alcohols. There are at least four alicyclic alcohols of commercial interest, two from the cyclohexyl family (cyclohexanol, methylcyclohexanols) and two from the furan family (furfuryl alcohol and tetrahydrofuran methanol). These alcohols are liquids. Cyclohexanol and furfuryl alcohol are the best studied alcohols of this group. Occupational exposure standards exist for these alcohols, except for tetrahydrofuran methanol. Unsaturated alcohols can be divided into olefinic (double bond) and acetylenic (triple bond) alcohols. Allyl alcohol is the most important olefinic alcohol as well as the most studied in this subset; propargyl alcohol and hexynol alcohol are the most commercially important acetylenic alcohols. There are also a number of other olefinic alcohols (C 5 ) and acetylenic alcohols (C 4 to C 10 ) with toxicity data. In general, these alcohols are liquids and are quite reactive. Occupational exposure standards exist for allyl alcohol and propargyl alcohol. The most important commercial members of the halogenated alcohol series are 2‐chloroethanol, or ethylene chlorohydrin, and chloropropanols, which are two isomers. These three alcohols exist as volatile liquids.