119 E.] 



PARAHYDROXYBENZOIC ALDEHYDE 



217 



& Co., Germ. Pat. 87972 of 1895; 

 Ber. 29, Ref. 747 : see also Germ. Pat. 

 80oi of 1896; Ber. 29, Ref. 1195). 

 The same polymeric anhydro-derivative 

 is obtained by the electrolysis of nitro- 

 benzene in the presence of hydrochloric 

 acid and formic aldehyde (Lob, Zeit. 

 Elektroch. 1898, 4, 428). 



From benzene through p-phenylene- 

 diamine (see under quinol [71 ; T]). 

 The latter combines with alloxan [Vol. 

 II] to form a product which, on heating 

 with sulphuric acid, gives p-aminoben- 

 zoic aldehyde, which can be treated as 

 above under B (Pellizari, Gazz. 17, 412 ; 

 Bohringer & Sohne, Germ. Pat. 108026 

 of 1898; Ch. Centr. 1900, 1, 1114). 



From toluene through p-nitrotoluene 

 and p-nitrobenzyl chloride (Wachen- 

 dorff, Ann. 185, 271), or through 

 benzyl chloride and nitration of the 

 latter (Beilstein and Geitner, Ann. 139, 

 337 > Strakosch, Ber. 6, 1056). The 

 nitrobenzyl chloride on oxidation with 

 lead nitrate and dilute nitric acid gives 

 p-nitrobenzoic aldehyde (Fischer and 

 Greiff, Ber. 13, 670), which can be 

 treated as above under B. 



Or p-nitrotoluene can be oxidised by 

 a mixture of sulphuric and chromic 

 acids in presence of acetic acid and 

 anhydride, when p-nitrobenzaldehyde 

 diacetate is formed, and this gives the 

 aldehyde on hydrolysis(Farbenfab. vorm. 

 F. Bayer & Co., Germ. Pat. 121788 of 

 1899; Ch. Centr. 1901, 2, 70). 



Or p-nitrobenzyl chloride can be 

 combined with aniline or its sulphonic 

 acid (Strakosch, Ber. 6, 1056 ; Paal 

 and Sprenger, Ber. 30, 69), and the 

 p-nitrobenzyl compounds oxidised to 

 benzylidene-compounds by acid and 

 dichromate, or with alkaline or neutral 

 oxidising mixtures (Meister, Lucius, 

 and Briining, Germ. Pats. 91503 of 

 1896; Ch. Centr. 1897, 1, 1007 ; 92084 

 of 1896; Ch. Centr. 1897, 2, 456; 

 93539 of 1897; Ch. Centr. 1897, 2, 

 1063; 97847 of 1896; Ch. Centr. 

 1898, 2, 696; 97948 of 1897; Ch. 

 Centr. 1898, 2, 742; 103859 of 1898; 

 Ch. Centr. 1899, 2, 949 ; 109608 of 

 1897; Ch. Centr. 1900, 2, 408; and 

 110173 of 1898; Ch. Centr. 1900, 2, 

 460). The p-nitrobenzylideneaniline or 



sulphonic acid obtained by this process 

 gives p-nitrobenzoic aldehyde (with the 

 base or its sulphonic acid) on hydrolysis 

 with dilute mineral acid (see also under 

 ben zoic aldehyde [114 ; A]). 



Or p-nitrobenzylideneaniline or its 

 sulphonic acid can be reduced to the 

 p-aminobenzylidene compound by alka- 

 line sulphides : the latter on hydrolysis 

 gives p-aminobenzoic aldehyde, which 

 can be converted into the hydroxy-alde- 

 hyde by the diazo-method as above under 

 B (Meister, Lucius, and Briining, Germ. 

 Pat. 99542 of 18975 Ch. Centr. 1899, 

 1, 238; Germ. Pat. 100968 of 1897; 

 Ibid. 958 : also Journ. Soc. Ch. Ind. 17, 

 658; 18, 363 and 488 for Eng. 

 Patents). 



Or p-nitrobenzyl chloride can be con- 

 verted into p-nitrobenzyl alcohol (or its 

 phenolsulphonic ether), which gives p- 

 aminobenzoic aldehyde on heating with 

 alkaline sulphides (Meister, Lucius, .and 

 Briining, Germ. Pat. 106509 of 1898; 

 Ch. Centr. 1900, 1, 1084). 



p-Nitrobenzyl chloride on combina- 

 tion with hydroxylamine gives fi-Q- 

 nitrobenzylhydroxylamine, which forms 

 a nitroso-derivative by the action of 

 nitrous acid. The nitroso-compound 

 decomposes on solution in acetic (with 

 nitric) acid with the formation of bis- 

 nitrosyl-p-nitrobenzyl, (NO 2 . C 7 H 6 ) 2 

 (NO) 2 (Behrend and Konig, Ann. 263, 

 216). Or the bisnitrosyl-compound can 

 be obtained by the action of bromine 

 water on p-nitrobenzylhydroxylamine 

 hydrochloride (Kjellin and Kuylen- 

 stjerna, Ber. 30, 1897). The bis- 

 nitrosyl-compound is decomposed by 

 caustic potash solution with the forma- 

 tion of p-nitrobenzaldoxime (a and /3) 

 (Behrend and Konig, loc. cit. 347). 

 Nitrobenzaldoxime is also formed from 

 nitrobenzylhydroxylamine as one pro- 

 duct of the action of bromine (Kjellin 

 and Kuylenstjerna, loc. cit.). The 

 nitrobenzaldoxime can be converted into 

 the amino-oxime, the ammo-aldehyde, 

 and the hydroxy-aldehyde as above 

 under B. (For convertibility of a- and 

 /3-oximes see Behrend, Ber. 24, 3088.) 



According to Geigy & Co. (Germ. 

 Pat, 86874 of 1 895 ; Ber. 29, Ref. 530) 

 p-nitrotoluene gives p-aminobenzoic 



