Patent GB-813172-A (GB)
Title: Improvements in or relating to method of oxidizing and cleaving organic compounds toform acidic products
IPC: C07C51/31
Filed: 1955-05-23
Abstract: A carboxylic acid is obtained from an organic compound, as defined below, which is capable of being oxidized and possibly cleaved by nitric acid or an oxidizing oxide of nitrogen, by first treating the organic compound with nitric acid or an oxidizing oxide of nitrogen, to form a nitrogen-containing organic compound, then reacting the resulting nitrogen - containing organic compound with an alkali to form an alkali metal derivative thereof and then treating said alkali metal derivative with an oxidizing agent under acidic conditions. The organic compound which is capable of being oxidized and possibly cleaved by nitric acid or an oxidizing oxide of nitrogen is defined as (1) an olefinic compound in which at least one of the olefinic carbon atoms carries a hydrogen atom; (2) an aliphatic or cycloaliphatic compound having a pair of adjacent carbon atoms one of which carries a hydroxy group or a ketonic oxygen group and the other of which carries at least two hydrogen atoms; (3) a saturated aliphatic or cycloaliphatic compound having adjacent carbon atoms one of which carries zero to three hydrogen atoms and the other of which carries two or three hydrogen atoms, said other carbon atom carrying three hydrogen atoms when the said one carbon atom carries less than two hydrogen atoms; and (4) an alkyl-substituted or a cycloalkyl-substituted aromatic compound or an alkyl-substituted heterocyclic compound. The oxidizing agent in the second oxidation step may be chromic acid, hot sulphuric acid, nitric acid or an oxidizing oxide of nitrogen, also an alkali metal permanganate or hot alkali metal hypochlorite may be used provided the alkali treated nitrogen-containing material is acidified prior to the introduction of such oxidizing agent.  The nitrogen-containing organic compound is preferably reacted with an excess of alkali and the alkali metal derivative is preferably treated with an excess of the oxidizing agent in the second stage.  The second stage oxidation may be carried out in the presence of an oxidation catalyst consisting of a salt of Mn, V, Cu or Co.  The process is preferably carried out by mixing together the organic compound and nitric acid or an oxidizing oxide of nitrogen, heating the mixture to 30 DEG  to 250 DEG  C. for up to 20 hours, desirably separating the nitrogen-containing material produced and then mixing with an excess of alkali, e.g. sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, or sodium alcoholate, heating the mixture to 30 DEG  to 130 DEG  C. for up to 20 hours and then re-oxidizing with a suitable oxidizing agent.  The initial nitric acid oxidation step and the treatment with alkali may be carried out batchwise or continuously and solvents or diluents may be present.  Examples are given for the oxidation of commercial oleic acid, linseed oil acids and the low-melting isomer of 9, 10-dihydroxystearic acid respectively to form mono- and di-basic acids, of 12-hydroxystearic acid to form dibasic acids and short-chained monobasic acids, of camphor to form white solids of acid number 490 and 450, of 9, 10-dihydroxystearic acid to form a short-chain acid fraction and higher fatty acids including stearic and palmitic acids, of commercial stearic acid to form various acid products including dibasic acids and a short-chain fatty acid fraction boiling in the range of propionic to heptanoic acids, of tetradecane to form dibasic acids (acid number 642) and short-chain fatty acids boiling in the range of butyric to octanoic acids, of ethyl benzene, using nitrogen dioxide as oxidizing agent in the first stage to form acid products having acid numbers of 330 and 426.9, of p-xylene to form a polybasic acid of acid number 527 and an acid fraction of acid number 500, of beta-picoline to form nicotinic acid which is first isolated in the form of its cupric salt, of p-xylene to form acid fractions believed to be impure toluic acid and terephthalic acid and acid products having acid numbers of 431 and 390, of paraffin wax to form products of acid numbers 286, 131.3 and 355, of commercial oleic acid to give various acid products, including short-chained mono-basic acids, while stearic and palmitic acids and other saturated acids are also recovered, and of cyclohexane to form adipic acid.  In each case (except where stated) nitric acid is used as the oxidizing agent in the first and second oxidation stages and all or part of the product from the first oxidation stage is treated with sodium hydroxide solution before the second oxidation stage.  Examples are also given in which commercial oleic acid is treated with a mixture of nitric acid and nitric oxides in the first oxidation stage and in which camphor is treated in the presence of acetic acid at 80-90 DEG  C. with nitrogen oxides (formed in a previous oxidation of camphor with hot nitric acid) in the first oxidation stage, nitric acid being used in each case in the second stage for the oxidation of the sodium hydroxide treated initial oxidation product.  Other starting materials specified are elaidic acid, erucic acid, undecylenic acid, 10,11 - dihydroxystearic acid, terpene 1,2-glycols, substituted 1, 2-hydroxy compounds, e.g. 9,10 - dihydroxystearonitrile, 9,10 - dihydroxystearamide, and N-benzoyl 9,10-dihydroxystearamine, 9-hydroxystearic acid, 10-hydroxystearic acid, terpene alcohols, 12-hydroxystearamide, 12-hydroxystearyl chloride, 12-ketostearic acid, 12-ketostearamide, 12-ketostearonitrile, iso-oleic acid, ricinoleic acid, linoleic acid, linolenic acid, fish oil acids, elaeostearic acid, rosin acids, glyceryl oleate, oleyl chloride, oleic nitrile, cyclohexene, mono- and poly-olefinic terpenes, polyolefinic compounds containing nitrile, amide or halide groups, kerosene, mineral lubricating oil, shale oil, hydrogenated coal tar, butyric, valeric, caproic, heptoic, caprylic, nonylic, capric, undecylic, lauric, tridecylic, myristic, pentadecylic, palmitic and margaric acids, toluene, xylenes, methyl quinolines, a -, b - and g -picolines, and beta-ethyl pyridine.  When the oxidation products include monobasic and dibasic acids, these may be separated by extraction with an alkane or by the addition of appropriate metal hydroxides, bicarbonates or carbonates or by making the solution neutral or alkaline and then adding appropriate metal salts, e.g. salts of calcium, barium, magnesium, lead or aluminium, to form insoluble salts of the dibasic acids. The process may be used to effect separation of unsaturated acids from saturated acids, e.g. commercial oleic acid may be submitted to oxidation under mild conditions in accordance with the invention to yield a mixture of dibasic acids, shortchain acids such as nonylic acid and palmitic and stearic acids, the dibasic acids and short-chain acids being then separated from the stearic and palmitic acids by distillation, crystallization, extraction, or a combination thereof.  The process may also be used to effect separation of long-chain unsaturated acids from long-chain saturated acids, the latter being relatively inert and for the separation of hydroxy or ketonic aliphatic acids from other saturated aliphatic acids, e.g. commercial 12-hydroxystearic acid containing stearic and palmitic acids may be treated to form a mixture containing stearic or palmitic acids, short-chain monobasic acids, e.g. caproic acid, and dibasic acids, from which the long-chain acids may be separated by conventional means.  The Specification also includes comparative examples in which commercial oleic acid, 9,10-dihydroxystearic acid, 12-hydroxystearic acid, and camphor respectively are oxidized with hot nitric acid in one stage to form acidic products.