The primary characteristic of the carbonyl compounds is polarity. Polarity of a compound also has an effect on how easily the human body can excrete toxic material that enters the body. Because the body is composed of primarily water, which is polar, polar compounds are more easily excreted through the body waste process than are nonpolar compounds. Formaldehyde exists normally as a gas that is readily polymerized with a strong pungent odor; however, it is also found as an aqueous solution from 37% to 50% concentrations. It is sometimes found with 15% methyl alcohol mixed in. Formaldehyde is toxic by inhalation with a TLV of 1 ppm in air. It is a strong irritant and a known carcinogen. Other aldehyde compounds include acetaldehyde and crotonaldehyde.
Ester is a hydrocarbon derivative family. They are flammable and toxic, and may undergo polymerization. Esters are members of the carbonyl family and are polar. They are used in the manufacturer of plastics. They are made from combining an organic acid and an alcohol with water as a by-product (Figure 3.116). Naming is based upon the acid and alcohol that
Figure 3.116 Esters are made from combining an organic acid and an alcohol with water as a by-product.
is used, so you will not find the name ester in the compounds. Saturated esters are not generally classified as hazardous materials. Their uses include food additives, and saturated esters have a sweet odor and are used as candy flavorings. Unsaturated esters are extremely dangerous. They are flammable and very toxic and undergo explosive polymerization. They can also self-polymerize in storage. They are used widely in the production of plastics.
Because ester is not in the name of the compounds, be on the lookout for names such as acrylate and acetate. You might see vinyl acrylate or methyl acetate for example. When you see acrylate and acetate, you are dealing with esters and the hazards mentioned above apply to all of them.
Vinyl acetate (CH3C02CH=CH2) is a colorless liquid used as the precursor to polyvinyl acetate, an important industrial polymer. It is flammable, mildly toxic and reactive.
Methyl acrylate (C4H502) is a colorless liquid with a characteristic acrid odor. It is mainly used to produce acrylate fiber, which is used to weave synthetic carpets. It is also a reagent of various pharmaceutical intermediates. It is highly flammable.
Organic acid is a hydrocarbon derivative family. It is toxic and corrosive. Corrosively is a form of toxicity to the tissues that the acid contacts. However, the organic acids have other toxic effects.
Formic acid is corrosive to skin and tissue. It has a TLV of 5 ppm in air and an IDLH of 30 ppm.
Acetic acid is toxic by ingestion and inhalation. It is a strong irritant to skin and tissues. The TLV is 10 ppm in air, and the IDLH is 1,000 ppm. Propionic acid is a strong irritant, with a TLV of 10 ppm in air. Butyric acid is a strong irritant to skin and tissues.
The degree of toxicity varies with the different organic acid compounds. Review reference sources and MSDS sheets to determine the exact hazards of specific acids.