Its methyl derivatives yield the corresponding carboxylic acids when oxidized by potassium permanganate.
On oxidation with chromic or nitric acids, or potassium permanganate, it yields nicotinic acid or (3-pyridine carboxylic acid, C 5 H 4 N CO 2 H; alkaline potassium ferricyanide gives nicotyrine, C10H10N2, and hydrogen peroxide oxynicotine, C10H14N20.
Phys., 1888 (6) 14, p. 435); by heating phenol carboxylic acids with baryta; and, in small quantities by the oxidation of benzene with hydrogen peroxide or nascent ozone (A.
7-dihydroxyxanthone, known as euxanthone, is prepared by heating euxanthic acid with hydrochloric acid or by heating hydroquinone carboxylic acid with 3-resorcylic acid and acetic anhydride (S.
7-trihydroxyxanthone, is found in the form of its methyl ether (gentisin) in gentian root; it is obtained synthetically by condensing phloroglucin with hydroquinone carboxylic acid.
Experience has shown that such mono-derivatives as nitro compounds, sulphonic acids, carboxylic acids, aldehydes, and ketones yield as a general rule chiefly the meta-compounds, and this is independent of the nature of the second group introduced; on the other hand, benzene haloids, amino-, homologous-, and hydroxy-benzenes yield principally a mixture of the orthoand para-compounds.
Another hexa-substituted benzene compound capable of direct synthesis is mellitic acid or benzene carboxylic acid, C6(000H)6.
Benzene and its homologues, carboxylic acids, and nitro compounds are much more stable towards oxidizing agents than.
An a-pyrrolidine carboxylic acid and its hydroxy derivatives have been detected by E.
Potassium persulphate oxidizes it in alkaline solution, the product on boiling with acids giving hydroquiirone carboxylic acid (German Patent 81,297).
Amino derivatives similarly result from thio-ureas and a-haloid ketones; the oxy derivatives from a-sulphocyanoketones by the action of caustic alkali; and the carboxylic acids from chloro-aceto-acetic ester, &c. and thioamides.
The benzothiazoles are a series of weak bases formed by condensing carboxylic acids with ortho-aminothiophenols (A.
In a similar manner, formic acid and dicyanophenylhydrazine yields a phenyl-triazole carboxylic acid, in which the phenyl group may be nitrated, the nitro group reduced to the amino group, and the product oxidized to a triazole carboxylic acid, which, by elimination of carbon dioxide, yields the free triazole: HO 2 C C=N H02C C =N, NPh-> N :CH N :CH They also result when the acidylthiosemicarbazides are strongly heated, the mercapto-triazoles so formed being converted into triazoles on oxidation with hydrogen peroxide (M.
This followed from a study of the decomposition products, there being obtained hemipinic acid (CH 3 0) 2 C 6 H 2 (000H) 2, and a substance which proved to be co - amino - ethyl - piperonyl carboxylic acid, CH 2 O 2 :C 6 H 2 [[Cooh-Ch 2 Ch 2 Nh]] 2.
Oxy-acids are carboxylic acids which also contain a hydroxyl group; similarly we may have aldehyde-acids, ketone-acids, &c. Since the more important acids are treated under their own headings, or under substances closely allied to them, we shall here confine ourselves to general relations.
Their alkyl derivatives readily oxidize to pyrazine carboxylic acids.
It is the carboxylic acid corresponding to tropine, for it yields the same products on oxidation, and by treatment with phosphorus pentachloride is converted into anhydroecgonine, C9H13N02, which, when heated to 280° C. with hydrochloric acid, splits out carbon dioxide and yields tropidine, C8H13N.
The diazo cyanides, C 6 H 5 N 2 CN, and carboxylic acids, C6H5.
Phenyl-azo-carboxylic acid, C 6 H 5 N 2 Cooh, is obtained in the form of its potassium salt when phenylsemicarbazide is oxidized with potassium permanganate in alkaline solution (J.
Alkaline potassium permanganate oxidizes it to phenyl-glyoxyl-ortho-carboxylic acid, H02C C6H4 CO.
Chromic acid in glacial acetic acid solution oxidizes it to picene-quinone, picene-quinone carboxylic acid, and finally to phthalic acid.
On oxidation .ith chromic acid it forms a quinone, C 15 H 8 0 2, and an a-diphenylene keto carboxylic acid C E I-4 3.
Duppa in 1865 examined the reaction and concluded that Geuther's sodium salt was a derivative of the ethyl ester of acetone carboxylic acid and possessed the constitution CH3COï¿½CHNaï¿½OOOC2H5.
It has a strongly acid reaction, being almost comparable with the carboxylic acids.
A little hydrochloric acid, methylene diresorcin [(HO) 2 C 6 H 3] 2 CH 2, whilst with chloral hydrate, in the presence of potassium bisulphate, it yields the lactone of tetra-oxydiphenyl methane carboxylic acid (J.
A-Aminopyridine, C5H4N NH2, is formed by heating 5-aminopyridine-2-carboxylic acid.
The oxypyridines may be prepared by distilling the corresponding oxypyridine carboxylic acids with lime, or by fusing the pyridine carboxylic acids with caustic potash.
The subjoined table shows the chief homologues of pyridine: Pyridine carboxylic acids are usually prepared by oxidizing the homologues of the base; they also result as decomposition products of various alkaloids.
Limpach, Ber., 1887, 20, P 947) Numerous carboxylic acids of quinoline are known, the most important of which are quinaldic, cinchoninic and acridinic acids.
Quinaldic acid (quinoline-a-carboxylic acid) is produced when quinaldine is oxidized by chromic acid.
One of the most important derivatives of diphenyl, from the theoretical point of view, is diphenic acid or diorthodiphenyl carboxylic acid, which can be obtained from diparadiaminodiphenyldiorthocarboxylic acid, H2N < j - < I > NH 2, or from phenanthrene, the consti Hooc Cooh tution of which it determines.
It may be obtained synthetically by Fittig and Tollens's method (above); by Friedel and Craft's process, devised in 1877, of acting with aluminium chloride on a mixture of benzene and methyl chloride; this reaction leads to the production of higher homologues which may, however, break down under the continued action of the aluminium chloride; or by heating the toluene carboxylic acids obtained by oxidizing the higher homologues of benzene.
Soc., 1888, 53, p. 1 94): C2H4Br2+2NaCH(C02R)2--->(CH 2) 2 C(CO 2 R) 2 +CH 2 (CO 2 R) 2; ethyl butane tetracarboxylate is also formed which may be converted into a tetramethylene carboxylic ester by the action of bromine on its disodium derivative (W.
C02R CH 3 CH: CBr CO 2 R+NaCH (CO 2 R) 2 --->CH 3 C. I C(C02R)2 by the action of diazomethane or diazoacetic ester on the esters of unsaturated acids, the pyrazoline carboxylic esters so formed losing nitrogen when heated and yielding acids of the cyclo- propane series (E.
Cyclo-propane carboxylic acid, C 3 H 5 CO 2 H, is prepared by heating the 1.1- dicarboxylic acid; and by the hydrolysis of its nitrile, formed by heating y-chlorbutyro-nitrile with potash (L.
It melts at 154-156° C., losing carbon dioxide and passing into cyclo-butane carboxylic acid, C 4 H 7 CO 2 H.
This basic acid yields a monobrom derivative which, by the action of aqueous potash, gives the corresponding hydroxycyclo-butane carboxylic acid, C 4 H 6 (OH) CO 2 H.
Wislicenus, Ann., 18 93, 2 75, p. 312), is also obtained by the action of sodium on the esters of pimelic acid; by the distillation of calcium succinate; and by hydrolysis of the cyclopentanone carboxylic acid, obtained by condensing adipic and oxalic esters in the presence of sodium ethylate.
3-cyclo-pentanol-3-carboxylic acidI) see W.