Azelaic acid, oxidation

Cleavage of an alkenoic acid can be carried out with permanganate, a permanganate—periodate mixture, periodate or with nitric acid, dichromate, ozone, or, if the unsaturation is first converted to a dihydroxy compound, lead tetraacetate (71,73). Oxidative ozonolysis is a process for the manufacture of azelaic acid [123-99-9] and pelargonic acid (74). 

The mixed oxidation products are fed to a stiU where the pelargonic and other low boiling acids are removed as overhead while the heavy material, esters and dimer acids, are removed as residue. The side-stream contains predominately azelaic acid along with minor amounts of other dibasic acids and palmitic and stearic acids. The side-stream is then washed with hot water that dissolves the azelaic acid, and separation can then be made from the water-insoluble acids, palmitic and stearic acids. Water is removed from the aqueous solution by evaporators or through crystallization (44,45). 

A U.S. patent describes the reaction of commercial oleic acid with hydrogen peroxide in acetic acid foUowed by air oxidation using a heavy metal compound and an inorganic bromine or chlorine compound to catalyze the oxidation. ExceUent yields of dibasic acids are obtained (up to 99%) containing up to 72% azelaic acid (55). 

There has been only one major use for ozone today in the field of chemical synthesis the ozonation of oleic acid to produce azelaic acid. Oleic acid is obtained from either tallow, a by-product of meat-packing plants, or from tall oil, a byproduct of making paper from wood. Oleic acid is dissolved in about half its weight of pelargonic acid and is ozonized continuously in a reactor with approximately 2 percent ozone in oxygen it is oxidized for several hours. The pelargonic and azelaic acids are recovered by vacuum distillation. The acids are then esterified to yield a plasticizer for vinyl compounds or for the production of lubricants. Azelaic acid is also a starting material in the production of a nylon type of polymer. 

The mechanism of inhibition by the salts of the long chain fatty acids has been examined . It was concluded that, in the case of the lead salts, metallic lead was first deposited at certain points and that at these points oxygen reduction proceeded more easily, consequently the current density was kept sufficiently high to maintain ferric film formation in addition, any hydrogen peroxide present may assist in keeping the iron ions in the oxide film in the ferric condition, consequently the air-formed film is thickened until it becomes impervious to iron ions. The zinc, calcium and sodium salts are not as efficient inhibitors as the lead salts and recent work has indicated that inhibition is due to the formation of ferric azelate, which repairs weak spots in the air-formed film. This conclusion has been confirmed by the use of C labelled azelaic acid, which was found to be distributed over the surface of the mild steel in a very heterogeneous manner. ... 

Cyclooctanone has been prepared by distilling the calcium and thorium salts of azelaic acid, by heating azelaic acid with barium oxide in the presence of iron, by the action of nitrous acid on l-(aminomethyl)-cycloheptanol, by Dieckman cyclization of azelaic acid dimethyl ester and diethyl ester, and by ring expansion of cycloheptanone with diazomethane. ... 

Other polyethers which have found limited application are polyethylene oxides) and some mixed polyester-polyethers such as Peedo-120 (Union Carbide), a diester of poly (1,4-butylene oxide )diol and azelaic acid. 

The diacids for these polymers are prepared via different processes. Azelaic acid [123-99-9] for nylon-6,9 [28757-63-3] is generally produced from naturally occurring fatty acids via oxidative cleavage of a double bond in the 9-position, eg, from oleic acid [112-80-1]... 

Pyridine, 33, 79 Pyridine, 3-amino-, 30, 3 5-eth yl-2-meth y l-, 30, 41 Pyridine-N-oxide, 33, 79 4-Pyrimidol, 2,6-diamino-, 32, 45 Pyrogallol-1,3-dimethyl ether, 31, 92 Pyrolysis, of ammonium salt of azelaic acid, 34, 4... 

Two step oxidation of tall oil fatty acid using peroxyformic acid and nitric acid/sodium metavanadate were used to produce azelaic acid. 

On an industrial scale, the traditional method for cleavage of carbon-carbon double bonds is ozonolysis, used for the manufacture of azelaic acid and nonanoic acids from oleic acid, and of butane tetracarboxylic acid from tetrahydrophthalic anhydride. The process is effectively a quantitative and mild process.178 However, it is capital and energy intensive. The intermediate ozonide is worked up either reductively or oxidatively to produce the aldehyde, ketone or carboxylic acid. Hydrogen peroxide is the common oxidizing agent used in the second step.179-181 Oxygen can also be used either alone182 or in combination with zeolites.183 Reviews on ozonolysis are available and the reader is directed to reference 184 for further information. 

Alkaline permanganate oxidation is frequently employed. Examples are 2,6-dimethylheptanoic acid (45%) from 3,7-dimethyI-l-octene, w-ethyl-phenylacetic acid (24%) ° from m-ethylallylbenzene, and azelaic acid (36%) ° from ricinoleic acid. 

Position of Double Bond.—The position of the double bond and the full constitution of oleic acid and elaidic acid has been established by means of the products obtained by careful oxidation. It has been shown that when compounds containing a double bond are thus oxidized the effect is to split the compound at the double bond with the oxidation of each doubly linked carbon group to carboxyl. Now both oleic acid and elaidic acid on oxidation yield two acids, each containing nine carbon atoms. One is a mono-basic acid known as pelargonic acid, CsHit—COOH and the other is a di-basic acid, azelaic acid, HOOC—C7H14—COOH. The reaction is... 

The results of some oxidations with potassium permanganate differ depending on the pH of the reaction. For example, stearolic acid gives 9,10-diketostearic acid at pH 7-7.5 (achieved with carbon dioxide) and azelaic acid on treatment at pH 12 [864]. In some reactions, potassium permanganate is used as a catalyst for oxidation with other oxidants, such as sodium periodate. Thus alkenes are cleaved to carbonyl compounds or acids via vicinal diols obtained by hydroxylation with potassium permanganate, followed by cleavage by sodium periodate [763, 552]. 

Undecylenic acid (10-undecenoic acid), when treated with potassium permanganate and sodium periodate in an aqueous solution of potassium carbonate at 20 °C for 20 h, gives sebacic acid (decane dioic acid) in 73% isolated yield [763]. A similar oxidation of oleic or elaidic acid yields a mixture of pelargonic acid and azelaic acid [763] (equation 474). 

Ozone, when combined with hydrogen peroxide [101] or peroxyacetic acid [268], cleaves the triple bond to yield carboxylic acids. Stearolic acid is converted into a mixture of pelargonic acid and azelaic acid [268] (equation 474). 9-Octadecynedioic acid, on treatment with ozone in acetic acid at room temperature followed by oxidation with hydrogen peroxide, gives azelaic acid in 81% yield [101]. 

The cleavage of oleic acid to azelaic acid and pelargonic acid with ozone as oxidant is one of the important industrial applications of ozonolysis [2]. However, finding a catalytic alternative to this unsuitable and hard-to-handle oxidant is in the interests of research groups all over the world. The cleavage of internal C=C double bonds by use of a Re, Mo, or W catalyst with H2O2 as oxidant, or a Ru catalyst with peracetic acid [12], is known. 

Side-reactions lead to the formation of lighter acids. For instance, monoperoxyadipic acid can decarboxylate to yield the pentanoic acid radical, precursor of the byproduct valeric acid. The same C5 radical may react with. O2 to yield 5-oxopentanoic acid, which is then oxidized to monoperoxyglutaric acid, a precursor of glutaric acid. An analogous mechanism starting from the butanoic acid radical may yield the byproduct succinic acid. Azelaic acid may form by the coupling of radical species (e.g., between the butanoic acid radical and the pentanoic acid radical), whereas the dimerization of the pentanoic acid radical may yield the by-product sebacic acid. 

Azelaic acid can be prepared by the oxidation of castor oil with nitric acid by the oxidation of ricinoleic acid with nitric acid and with alkaline permanganate by the oxidation of methyl oleate with alkaline permanganate by the ozonization of oleic acid and decomposition of the ozonide by the ozonization of methyl ricinoleate and decomposition of the ozonide by the action of carbon dioxide upon 1,7-heptamethylene magnesium bromide by the hydrolysis of i,7-di(yanoheptane. ... 

The crude substance is dissolved in 1200 cc. of boiling water, filtered with suction, and allowed to cool. The crystals are filtered, washed with water, and dried. There is obtained 48-55 g. of product (32-36 per cent of the theoretical amoimt, based upon the amoimt of crude ricinoleic acid taken for oxidation). The melting point of the purified azelaic acid is 104-106°. 

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