General Description
TRIMETHYLACETIC ACID(75-98-9) is a colored crystalline solid of low toxicity that is soluble in water, ethyl alcohol and diethyl ether.
Reactivity Profile
TRIMETHYLACETIC ACID is a carboxylic acid. Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water. Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in TRIMETHYLACETIC ACID to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.
Air & Water Reactions
With mixing, water soluble.
Health Hazard
CALL FOR MEDICAL AID. SOLID: Irritating to eyes and skin. Harmful if swallowed. IF IN EYES OR ON SKIN, flush with running water for at least 15 minutes; hold eyelids open if necessary. Wash skin with soap and water. Remove and isolate contaminated clothing and shoes at the site. If SWALLOWED and victim is UNCONSCIOUS OR HAVING CONVULSIONS, do nothing except keep victim warm. Because of low volatility, it is relatively harmless when inhaled at normal ambient temperature (around 20°C). It is slightly toxic by ingestion or skin absorption. The vapor is irritating at elevated temperatures. Can cause considerable discomfort by oral routes; may cause reversible or irreversible changes to exposed tissue, not permanent injury or death.
Fire Hazard
COMBUSTIBLE. Produces vapors irritating to eyes and skin. Decomposes to produce acrid smoke and fumes.
Chemical Properties
white crystalline low melting mass
Uses
Pivalic Acid is a metabolite of oral cephem (β-lactam) antibiotics such as S-1108, containing pivaloyl moieties.
Definition
ChEBI: Pivalic acid is a branched, short-chain fatty acid composed of propanoic acid having two methyl substituents at the 2-position. It is a branched-chain saturated fatty acid, a methyl-branched fatty acid and a short-chain fatty acid. It is a conjugate acid of a pivalate.
Preparation
Pivalic acid is prepared through the bromoform reaction on pinacolone, or from tert-butyl chloride, magnesium and carbon dioxide; a recent improvement involves the reaction of tert-butyl chloride, lithium and magnesium-2-ethoxyethanate[1].
Synthesis Reference(s)
Journal of the American Chemical Society, 98, p. 1275, 1976
DOI: 10.1021/ja00421a046Organic Syntheses, Coll. Vol. 1, p. 524, 1941
reaction suitability
reaction type: C-H Activation
Purification Methods
Fractionally distil the acid under reduced pressure, then fractionally crystallise it from its melt. Recrystallise it from *benzene. [Beilstein 2 IV 908.]
References
[1] Hamilton, G.S. and Ladd, C.L. (2015). Pivalic Acid. In Encyclopedia of Reagents for Organic Synthesis. https://doi.org/
10.1002/047084289X.rp176.pub2
