Neopentanoic acid

I eopentanoic (Pivalic) Acid. Neopentanoic acid [75-98-9] is prepared using the Koch technology in which isobutylene reacts with carbon monoxide in the presence of strong acids such as H2SO4, HF, and BF H20 (119—122). General reaction conditions are 2—10 MPa (about 20—100 atm) of CO and 40-150°C. 

Table 1. Physical Properties of Commercially Available Neopentanoic Acid ...

Chemical Properties. Neopentanoic acid [75-98-9] undergoes reactions typical of carboxyUc acids. Reactions often proceed less readily than with straight-chain acids because of the steric hindrance around the carbonyl group. However, this steric hindrance at the a-carbon results ia derivatives that are typically more resistant to hydrolysis and oxidation. 

Acid Chloride Formation. Neopentanoic acid can be converted to neopentanoyl chloride [3282-30-2] by reaction with thionyl chloride (2), phosgene (3), phosphoms pentachloride, phosphoms trichloride, or by the reaction with henzotrichloride ia the presence of Eriedel-Crafts catalysts (4). A laboratory procedure usiag tetramethyl-a-halogenoenamines at room temperature has also been reported (5). 

Reduction. 2,2-Dimeth5lpropanal [630-19-3] can be prepared by the reduction of neopentanoic acid usiag various catalysts, such as iroa (14), tin or zirconium oxides (15,16), iron—chromium (17), and other reagents (18,19). The reduction of neopentanoic acid to 2,2-dimeth5lpropaaol [75-84-3]... 

Other Rea.ctlons, The anhydride of neopentanoic acid, neopentanoyl anhydride [1538-75-6] can be made by the reaction of neopentanoic acid with acetic anhydride (25). The reaction of neopentanoic acid with acetone using various catalysts, such as titanium dioxide (26) or 2irconium oxide (27), gives 3,3-dimethyl-2-butanone [75-97-8] commonly referred to as pinacolone. Other routes to pinacolone include the reaction of pivaloyl chloride [3282-30-2] with Grignard reagents (28) and the condensation of neopentanoic acid with acetic acid using a rare-earth oxide catalyst (29). Amides of neopentanoic acid can be prepared direcdy from the acid, from the acid chloride, or from esters, using primary or secondary amines. 

Neopentanoic acid has also been produced commercially from diisobutylene [18923-87-0], in which the first step in the reaction sequence is a cracking or depolymeri2ation of the olefin to give isobutylene. 

Work on the process for the production of these acids has continued in recent years. One patent discloses the use of 2eohte catalysts (34) for the synthesis of neopentanoic acid from isobutylene. The use of a copper catalyst in a strong acid, such as sulfuric acid, operating at lower pressures, has also been claimed (35). 

Economic Aspects and Shipment. Production worldwide of neopentanoic acid is estimated at 15 thousand metric tons per year. Both Shell (36) and Exxon (37) have aimounced expansions in capacity. Neopentanoic acid is shipped in heated tank cars, heated tank tmcks, and dmms. 

Health and Safety Factors. Neopentanoic acid possesses low toxicity, either by ingestion (oral LD q in rats is 2.0 g/kg) or by skin absorption (dermal LD q in rabbits is 3.16 g/kg). The principal ha2ards associated with neopentanoic acid at ambient temperatures are from eye and skin irritation. At elevated temperatures, where concentrations of the vapor are significant, irritation of the respiratory tract can also occur. Contact with the material should be avoided. 

Eye contact should be followed by flushing the eyes with large amounts of water. If irritation persists, medical attention should be obtained. Skin contact should be followed by flushing with water, using soap if available. Neopentanoic acid is combustible and will bum. Eire should be extinguished with foam, dry chemical, or water spray. 

Polymers ndResins. / fZ-Butyl peroxyneopentanoate and other peroxyesters of neopentanoic acid can be used as free-radical initiators for the polymeri2ation of vinyl chloride [75-01-4] (38) or of ethylene [74-85-1]. These peresters have also been used in the preparation of ethylene—vinyl acetate copolymers [24937-78-8] (39), modified polyester granules (40), graft polymers of arninoalkyl acrylates with vinyl chloride resins (41), and copolymers of A/-vinyl-pyrrohdinone [88-12-0] and vinyl acetate [108-05-4] (42). They can also be used as curing agents for unsaturated polyesters (43). 

Pha.rma.ceutica.ls. Neopentanoic acid derivatives are widely used in the preparation of pharmaceuticals, eg, as a means of introducing the tert-huty group into a molecule. More frequendy, however, derivatives have been prepared that exploit the enhanced hydrolytic stabiUty of the neopentanoate group. Eor example, when salmon calcitonin is treated with N-hydroxysuccinimide pivalate [42014-50-6], the resulting derivative retains the biological activity of the precursor, but gives an extended duration of activity (51). 

Cosmetics. Esters of neopentanoic acid are used as perfumes or perfume precursors (8,67), as Hquid binders (68), and in em ollient and moisturi2ing compositions (69). 

Fuels, Lubricants, and Transmission Fluids. Polyol esters of neopentanoic acid have been used as high vacuum pumping hquids that are stable in chemically aggressive environments (70). Esters such as 6- -ani1inophenoxy)hexy1 pivalate are used as antioxidants for synthetic ester lubricants (71). PivaUc anhydride [1538-75-6] has been claimed as an antiknock additive for gasoline (72). 

Chemical Properties. Like neopentanoic acid, neodecanoic acid, C2QH2QO2, undergoes reactions typical of carboxyHc acids. For example, neodecanoic acid is used to prepare acid chlorides, amides (76), and esters (7,11,77,78), and, like neopentanoic acid, is reduced to give alcohols and alkanes (21,24). One area of reaction chemistry that is different from the acids is the preparation of metal salts. Both neopentanoic acid and neodecanoic acid, like all carboxyHc acids, can form metal salts. However, in commercial appHcations, metal salt formation is much more important for neodecanoic acid than it is for neopentanoic acid. 

The addition of carhon monoxide to isobutylene under high pressures and in the presence of an acid produces a carhon monoxide-olefin complex, an acyl carhocation. Hydrolysis of the complex at lower pressures yields neopentanoic acid ... 

Neopentanoic acid (trimethylacetic acid) is an intermediate and an ester-ifying agent used when a stable neo structure is needed. 

Neon—helium continuous lasers, 17 372 Neonicotinoid insecticides, 14 346 Neopentanal trifluoroborane, 4 144t Neopentanoic acid, 5 60-65 physical properties, 5 60t production from butylenes, 4 427 Neopentyl glycol, 12 670-672... 

Carhonyintion - Neopentanoic acid Resins - Paints (pure isobutylene)... 

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