It is also formed by heating benzoic anhydride with glycocoll (Th.
Pechmann, Ber., 18 9 5, 28, p. 857); by distilling anisic acid (paramethoxy benzoic acid) with baryta or by boiling phenyl diazonium chloride with methyl alcohol.
The classical investigation of Liebig and Friedrich Wihler on the radical of benzoic acid (" Uber das Radikal der Benzoesaure," Ann.
An, matter), formed the basis of benzaldehyde, benzoic acid, benzoyl chloride, benzoyl bromide and benzoyl sulphide, benzamide and benzoic ether.
However, in 1833, Berzelius reverted to his earlier opinion that oxygenated radicals were incompatible with his electrochemical theory; he regarded benzoyl as an oxide of the radical C 14 H 1Q, which he named " picramyl " (from 7rucp6s, bitter, and &uvyalk, almond), the peroxide being anhydrous benzoic acid; and he dismissed the views of Gay Lussac and Dumas that ethylene was the radical of ether, alcohol and ethyl chloride, setting up in their place the idea that ether was a suboxide of ethyl, (C2H5)20, which was analogous to K 2 0, while alcohol was an oxide of a radical C 2 H 6; thus annihilating any relation between these two compounds.
This compound is readily oxidized to benzoic acid, C 6 H 5 000H, the aromatic residue being unattacked; nitric and sulphuric acids produce nitro-toluenes, C6H4 CH3 N02j and toluene sulphonic acids, C 6 H 4 CH 3 SO 3 H; chlorination may result in the formation of derivatives substituted either in the aromatic nucleus or in the side chain; the former substitution occurs most readily, chlor-toluenes, C 6 H 4 CH 3 Cl, being formed, while the latter, which needs an elevation in temperature or other auxiliary, yields benzyl chloride, C 6 H 5 CH 2 C1, and benzal chloride, C 6 11 5 CHC1 2.
OH, in which we will assume the hydroxyl group to occupy position I, is converted into brombenzene, which is then converted into benzoic acid, C 6 1-1 5 -COOH.
OH COOH, may be prepared; and the two other known oxybenzoic acids (ortho- and para-) may be converted into benzoic acid.
Of other syntheses of true benzene derivatives, mention may be made of the formation of orcinol or [3 s]-dioxytoluene from dehydracetic acid; and the formation of esters of oxytoluic acid (5-methyl3-oxy-benzoic acid), C6 H3 CH3.
It is well known that di-orthosubstituted benzoic acids are esterified with difficulty.
Benzoic acid is pseudo-tetragonal, the principal axis being remarkably long; there is no cleavage at right angles to this axis.
These are also pseudotetragonal; the (1.3.6) acid has nearly the same values of x and l,t as benzoic acid, but w is increased; compared with m-nitrobenzoic acid, x and 1,1.
Japaconitine, obtained from the Japanese aconites, known locally as "kuza-uzu," hydrolyses to japbenzaconine, which further breaks down to benzoic acid and japaconine.
2-dioxy-3-benzoic acid, C 6 113(OH)2000H.
Liebig in 1829 showed that it differed from benzoic acid, and in 1839 determined its constitution, while in 1853 V.
It crystallizes in rhombic prisms which are readily soluble in hot water, melt at 187° C. and decompose at about 240° C. It is readily hydrolysed by hot caustic alkalis to benzoic acid and glycocoll.
Mitscherlich prepared it in 1834 by distilling benzoic acid with lime; and in 1845 Hofmann discovered it in coal-tar.
Manganese dioxide and sulphuric acid oxidize it to benzoic and o-phthalic acid; potassium chlorate and sulphuric acid breaks the ring; and ozone oxidizes it to the highly explosive white solid named ozo-benzene, C 6 H 6 O 6.
Styrolene is oxidized by nitric or chromic acids to benzoic acid; reduction gives ethylbenzene; hydrochloric and hydrobromic acids yield a-haloid ethylbenzenes, e.g.
An important oxidation synthesis of aromatic acids is from hydrocarbons with aliphatic side chains; thus toluene, or methylbenzene, yields benzoic acid, the xylenes, or dimethyl-benzene, yield methyl-benzoic acids and phthalic acids.
A similar change, in one direction only, characterizes benzoic acid and salicylic acid.
Thus, with the tolylphenylketoximes, one yields the anilide of toluic acid and the other the toluidide of benzoic acid, the former necessitating the presence of the phenyl and hydroxyl radicals in the syn position and the latter the tolyl and hydroxyl radicals in the syn position, thus: CH3 C6H4 C C6H5
It is reduced by nascent hydrogen to the secondary alcohol C6H5.CH.OH.CH3 phenyl-methyl-carbinol, and on oxidation forms benzoic acid.
P. Luff obtained apoaconitine, aconine and benzoic acid by hydrolysis; while, in 1892, C. Ehrenberg and A.
The odour of Siam benzoin is partly due to the presence of vanillin, and the substance contains as much as 38% of benzoic acid but no cinnamic acid.
It contains about 20% of cinnamic acid in addition to 18 or even more of benzoic. (3) Palembang benzoin, an inferior variety, said to be obtained from Styrax benzoin in Sumatra, consists of greyish translucent resinous masses, containing small white opaque tears.
Its medicinal uses depend on the contained benzoic acid.
Dorp (Ber.,1874,7,P.578) obtained orthobenzoyl benzoic acid by heating phthalic anhydride with benzene in the presence of aluminium chloride.
Dioxyand tetraoxy-anthraquinones are obtained when meta-oxyand dimeta-dioxy-benzoic acids are heated with concentrated sulphuric acid.
When fused with caustic potash, it gives benzoic acid.
To obtain it perfectly pure the crude alcohol is combined with oxalic, benzoic or acetic acid, and the resulting ester separated, purified, and finally decomposed with potash.
The product on acidification gives a compound C15H1205 ï¿½ H20 which is probably an oxy-methoxy-benzoyl benzoic acid.
BENZOIC ACID, C 7 H 6 0 2 or C 6 H S 000H, the simplest representative of the aromatic acids.
For this purpose the urine is concentrated and the hippuric acid precipitated by the addition of hydrochloric acid; it is then filtered and boiled for some time with concentrated hydrochloric acid, when it is hydrolysed into benzoic and amido-acetic acid.
Benzoic acid crystallizes in glistening leaflets (from water) which melt at 121.4° C. and boil at 249.2° C. (H.
The salts of benzoic acid are known as the benzoates and are mostly soluble in water.
They are readily decomposed by mineral acids with the production of benzoic acid, and on addition of ferric chloride to their neutral solutions give a reddish-brown precipitate of ferric benzoate.
Benzoic anhydride, (C 6 H 5 C0) 2 0, is prepared by the action of benzoyl chloride on sodium benzoate, or by heating benzoyl chloride with anhydrous oxalic acid (R.
Benzoyl chloride, C 6 H S 0001, is formed by distilling a mixture of phosphorus pentachloride and benzoic acid; by the action of chlorine on benzaldehyde, or by passing a stream of hydrochloric acid gas over a mixture of benzoic acid and phosphorus pentoxide heated to 200°C. (C. Friedel, Ben.
Ethyl benzoate, C 6 H S 000C 2 H 5, is best prepared by boiling benzoic acid and alcohol with a small quantity of sulphuric acid for some hours (E.
It crystallizes (from water) in glistening leaflets which melt at 130° C. and boil at 288° C. Its silver salt behaves as if it were the salt of an imido benzoic acid, since it yields benzimido ethyl ether C 6 H 5 C(:NH) OC 2 H 5 with ethyl iodide (J.
Chlor-, brom-, iodoand fluor-benzoic acids are known and can be obtained by oxidizing the corresponding halogen toluenes, or from the amido acids, or by substitution.