Appendix I - Hazards Of Functional Groups

The following information provides a basic overview of functional group hazards. This is not meant to replace material safety data sheets for specific chemicals used in your experiments. While listed alphabetically for convenience, chemicals should be segregated and stored by hazard classes per the EHS Segregation Scheme.

Alcohols - Lower aliphatic alcohols have low to moderate toxicity and vapor pressure. Health hazards primarily from ingestion and skin absorption. Fatty alcohols are nearly nontoxic. Flammability and toxicity generally decrease with increasing carbon chain length. Examples: methanol, ethanol, 1-butanol.

Aldehydes - Intermediate products in alcohol-carboxylic acid conversions. Lower molecular weight aldehydes are more toxic and highly flammable than higher ones. Aromatic aldehydes are less toxic than low molecular weight aliphatic aldehydes. Examples: formaldehyde, acetaldehyde, benzaldehyde.

Aliphatic Amines - Low to moderate toxicity with severe irritation to skin, eyes, and mucous membranes due to caustic nature. Strong ammonia odor. Lower amines are highly flammable (many with flashpoints below 0°C) and react vigorously with mineral acids. Examples: methylamine, ethyleneimine.

Aliphatic and Alicyclic Hydrocarbons - Compounds of only carbon and hydrogen including alkanes, alkenes, alkynes, and cyclic compounds. Very low toxicity; gaseous forms are simple asphyxiants. Primary hazard is flammability, which decreases with increasing carbon number. Examples: methane, butane, cyclohexene.

Alkali and Other Reactive Metals - Groups IA and IIA metals that can be water/air reactive and flammable in finely divided states. React with water to produce strong bases. Examples: sodium, potassium, magnesium.

Alkalies - Water-soluble bases, mainly hydroxides of alkali/alkaline-earth metals. Severe corrosive action on tissues, bitter taste, skin corrosion, and eye irritation. React exothermically with water and acids. Examples: sodium hydroxide, potassium hydroxide.

Aromatic Amines - Amino groups attached to aromatic rings. Less basic than aliphatic amines but present two major health hazards: moderate to severe poisoning and carcinogenicity (especially bladder cancer). Many are proven/suspected carcinogens. Combustible and may react violently with oxidizers. Examples: aniline, benzidine.

Aromatic Hydrocarbons - Benzene-ring structures. Many polyaromatics are carcinogens. Low acute toxicity but may cause narcosis at high concentrations. Benzene is the only mononuclear aromatic with possible human carcinogenicity. Examples: benzene, toluene, xylene.

Azides, Fulminates, Acetylides - Form highly explosive, shock/heat-sensitive salts with metals. Highly unstable with explosion hazards, especially Group IB and IIB metal salts. May explode from impact, heat, chemical contact, or light exposure. Examples: sodium azide, mercury fulminate.

Carboxylic Acids - Weak organic acids with moderate to low toxicity that decreases with carbon chain length. Low molecular weight acids are combustible liquids. Aromatic acids have low toxicity. Examples: acetic acid, formic acid, oxalic acid.

Epoxy Compounds - Strong irritants to skin, eyes, and respiratory tract. Lower molecular weight epoxides are more toxic. Many cause cancer in animals. Highly flammable and polymerize readily with acids/catalysts, generating dangerous heat and pressure. Examples: ethylene oxide, epichlorohydrin.

Esters - Pleasant fruity odor with generally low acute toxicity but narcotic at high concentrations. Lower aliphatic esters are flammable with some having low flash points. Aromatic esters have similar effects. Examples: ethyl acetate, methyl formate.

Ethers - Widely used solvents with high flammability and tendency to form explosive peroxides. Lower aliphatic ethers are among the most flammable organic compounds. Aromatic ethers are noncombustible. Low toxicity with anesthetic effects at high concentrations. Examples: ethyl ether, isopropyl ether.

Glycol Ethers - Also known as Cellosolves. Mild toxic effects with exposure through inhalation, ingestion, and skin absorption. Low molecular weight compounds are flammable/combustible. Examples: ethylene glycol monomethyl ether.

Haloethers - Halogen substitution makes ethers less/non-flammable and inhibits peroxide formation. Fluoroethers produce anesthesia; chloro/bromoethers can injure lungs. Many are carcinogenic. Examples: bis(chloromethyl)ether.

Halogenated Hydrocarbons - Variable flammability with low acute toxicity. Health hazards include anesthetic effects, liver/kidney damage, and carcinogenicity. May react violently with alkali metals or powerful oxidizers. Examples: carbon tetrachloride, chloroform, methylene chloride.

Hydrides - Highly reactive with water, potentially explosive with hydrogen liberation. Many ignite spontaneously in moist air and are powerful reducing agents. Volatile covalent hydrides are highly toxic; ionic hydrides are corrosive. Examples: lithium aluminum hydride, sodium hydride.

Industrial Solvents - Generally low toxicity but most are flammable/combustible with explosive vapor mixtures. Some cause flashback and form peroxides on storage. Examples: acetone, tetrahydrofuran, pyridine.

Inorganic Cyanides - Metal salts of hydrocyanic acid. Alkali metal cyanides are extremely toxic and form deadly hydrogen cyanide when contacting acids. Examples: sodium cyanide, potassium cyanide.

Ketones - Similar to aldehydes but generally lower toxicity. Some simple ketones are less toxic than higher ones. Simplest ketones are highly flammable. Examples: acetone, methyl ethyl ketone.

Mineral Acids - Variable acid strength, all corrosive. React with bases to form salts, produce hydrogen with metals, and carbon dioxide with carbonates. Noncombustible but some highly reactive. Examples: hydrochloric acid, sulfuric acid, nitric acid.

Organic Cyanides (Nitriles) - Highly reactive and toxic compounds, some as toxic as alkali metal cyanides. Lower aliphatic nitriles are flammable with explosive air mixtures. Examples: acetonitrile, acrylonitrile.

Organic Isocyanates - Highly reactive due to unsaturation. Hazardous lachrymators and irritants causing skin/mucous membrane problems. Inhalation can cause asthma-like reactions. Low fire hazard due to high flash points. Examples: methyl isocyanate.

Organic Peroxides - Low to moderate toxicity but extremely dangerous to handle. Powerful oxidizers that are highly flammable and may explode from shock, heat, or chemical contact. Active oxygen content >9% is too dangerous for handling. Examples: benzoyl peroxide, cumene hydroperoxide.

Oxidizers - Strong oxidizing agents rich in oxygen that decompose violently when heated. Explosion hazard when contacting organics, metals, or hydrides. Health hazards from corrosive action, toxicity depends on metal ions. Examples: nitrates, perchlorates, permanganates.

Peroxy Acids - Two types: peroxycarboxylic and peroxysulfonic acids. Highly unstable, decompose violently when heated, and react dangerously with organic matter. Most powerful oxidizing organic peroxides. Health hazard primarily from irritation. Examples: peroxyacetic acid.

Phenols - Hydroxyl groups attached to aromatic rings, making them weakly acidic. Show relatively greater toxicity compared to many organic compound classes. Examples: phenol, cresol, pentachlorophenol.

Phthalate Esters - Esters of phthalic acid that are noncombustible liquids. Very low acute toxicity and relatively harmless, among the least toxic organic industrial products. Some are EPA priority pollutants. Examples: dibutyl phthalate, DEHP.

Reference: Patnaik, Pradyot, A Comprehensive Guide to the Hazardous Properties of Chemical Substances, Van Nostrand Reinhold, 1992.