See also:

• BENZIDINE (DIPARA-DIAMINO-DIPHENYL), NH2

BENZIDINE (DIPARA-DIAMINO-See also:

• DIPHENYL (phenyl benzene), C6H5

DIPHENYL), See also:

• NH2

NH2  • See also:

• C6H4
• C6H4(CH213r)2

C6H4 • C6H4 • See also:

• NH2

NH2, a chemical See also:

• BASE

base which may be prepared by the reduction of the corresponding dinitro-See also:

• DIPHENYL (phenyl benzene), C6H5

diphenyl, or by the reduction of azobenzene with See also:

• TIN (Lat.- stannum, whence the chemical symbol " Sn "; atomic weight =117.6, 0=16)

tin and hydrochloric See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid . In this latter See also:

• CASE
• CASE, JOHN (d. 1600)

case hydrazo-See also:

• BENZENE, C6H6

benzene C6H5NH•NH•See also:

• C6H5

C6H5 is first formed and then undergoes a See also:

• PECULIAR

peculiar re-arrangement into See also:

• BENZIDINE (DIPARA-DIAMINO-DIPHENYL), NH2

benzidine (see H . See also:

• SCHMIDT, H
• SCHMIDT, HEINRICH JULIAN (1818-1886)
• SCHMIDT, KARL VON (1817-1875)
• SCHMIDT, WILHELM ADOLF (1812-1887)

Schmidt and G . See also:

• SCHULTZ, HERMANN (1836- )

Schultz, Annalen, 1881, 207, p . 320; O . N . Witt and Hans v . See also:

• HELMONT, JEAN BAPTISTE VAN (1577—1644)

Helmont, Berichte, 1894, 27, p . 2352; P . Jacobson, Berichte, 1892, 25, p . 994) . Benzidine crystallizes in plates (from See also:

• WATER

water) which melt at 122° C., and See also:

• BOIL

boil above 36o° C., and is characterized by the See also:

• GREAT

great insolubility of its sulphate .

It is a di-acid base and forms salts with the See also:

• MINERAL

mineral acids . It is readily brominated and nitrated; when the nitration is carried out in the presence of sulphuric acid, the nitro-See also:

• GROUPS
• GROUPS, THEORY

groups take up the See also:

• META

meta position with regard to the amino-groups . Benzidine finds commercial application since its tetrazo See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound couples readily with amino-sulphonic acids, phenol carboxylic acids, and phenol and naphthol-sulphonic acids to produce substantive See also:

• COTTON
• COTTON (Fr. coton; from Arab. qutun)
• COTTON, CHARLES (163o–1687)
• COTTON, GEORGE EDWARD LYNCH (1813–1866)
• COTTON, JOHN (1585–1652)
• COTTON, SIR ROBERT BRUCE

cotton dyes (see See also:

• DYEING (0. Eng. dedgian, dealt ; Mid. Eng. deyen)

DYEING) . Among such dyestuffs are chrysamine or flavophenine, obtained from salicylic acid and diazotized benzidine, and See also:

• CONGO

congo red obtained from See also:

• SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium naphthionate and diazotized benzidine . On the constitution of benzidine see G . Schultz (Annalen, 1874, 174, p . 227) . The See also:

• BEN (from Old Eng. bennan, within)

Ben€idine and Semidine See also:

• CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

Change.—Aromatic hydrazo compounds which contain See also:

• FREE

free See also:

• PARA
• PARA (officially BELEM; sometimes BELEM DO PARA)

para positions are readily converted by the See also:

• ACTION

action of acids, acid chlorides and anhydrides into diphenyl derivatives; thus, as mentioned above, hydrazobenzene is converted into benzidine, a small quantity of diphenylin being formed at the same See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time . The two products are separated by the different solubilities of their sulphates . This reaction is known as the benzidine transformation . If, however, one of the para positions in the hydrazo compound is substituted, then either diphenyl derivatives or See also:

• AZO (c. 1150-1230)

azo compounds are formed, or what is known as the semidine change takes See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place (P . Jacobson, Berichte, 1892, 25, p .

992; 1893, 26, p . 681; 1896, 29, p . 268o; Annalen, 1895, 287, p . 97; 1898, 303, p . 290) . A para mono substituted hydrazo compound in the presence of a hydrochloric acid See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of stannous chloride gives either a para diphenyl derivative (the substituent See also:

• GROUP

group being eliminated), an ortho-semidine, a para-semidine, or a diphenyl base, whilst a decomposition with the formation of See also:

• AMINES

amines may also take place . The nature of the substituent exerts a specific See also:

• INFLUENCE (Late Lat. influentia, from influere, to flow in)

influence on the reaction; thus with See also:

• CHLORINE (symbol Cl, atomic weight 35`46 (0=16)

chlorine or See also:

• BROMINE (symbol Br, atomic weight 79-96)

bromine, ortho-semidines and the diphenyl bases are the See also:

• CHIEF (from Fr. chef, head, Lat. caput)

chief products; the dimethylamino, -N(See also:

• CH3

CH3)2, and acetamino, -NHCOCH3, groups give the diphenyl base and the para-semidine respectively . With a methyl group, the chief product is an ortho-semidine, whilst with a carboxyl group, the diphenyl derivative is the chief product . The ortho- and para- semidines can be readily distinguished by their behaviour with different reagents; thus with nitrous acid the ortho-semidines give azimido compounds, whilst the para-semidines give complex diazo derivatives; with formic or acetic acids the ortho-semidines give anhydro compounds of a basic See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character, the para-semidines give acyl products possessing no basic character . The See also:

• CARBON (symbol C, atomic weight 12)

carbon disulphide and salicylic aldehyde products have also been used as means of distinction, as has also the formation of the stilbazonium bases obtained by condensing ortho-semidines with benzil (0 . N . Witt, Berichte, 1892, 25, p .

1017) . Structurally we have: NH2 -NH•NH—( > —j NH2<)—< >NH2 and NH2 < >—<—% Hydrazohenzene . Benzidine . Diphenylin . NH2 R< >—NH•NH—< > —> < )—NH—<----> or RK > —NH— NH_, R Ortho-semidine . Para-semidine . NH2 or( >—< )NIH2 .