If, on the other hand, nitrosodimethylaniline,
NO
|
C_6H_4
|
(CH_3)_2
is sulphonated, and the water-soluble sulphonation product heated with formaldehyde for some time, the product remains soluble in water and precipitates gelatine. No tanning effect could, however, be detected.
Arylsulphaminoarylsulphonic acids and arylsulphoxyarylsulphonic acids precipitate gelatine but are devoid of tannoid character. The latter is acquired by compounds belonging to this class containing two or more sulphamino groups, or when they, in addition to one sulphamino group, contain a sulphoxy group and another sulphonic group. According to Ger. Pat., 297,187 (Society oc Chemical Industry, Basle), such compounds are obtained when, for instance, sodium sulphanilide in alkaline solution acts upon nitrotoluenesulphochloride, and the resulting nitrotoluenesulphamino compound is subsequently reduced with acetic acid and iron. The resulting aminotoluenesulphaminobenzenesulphonic acid is finally treated with p-toluenesulphonic chloride till the latter disappears. A compound of the composition
——-NH——-SO_2——-
^ ^ ^
| | | | | |
| | | |—-NH—-| |
V V V
SO_2Na CH_2
is thereby obtained, which, when acidified, is readily capable of being used for tanning purposes.
The intermediary product of the aminotoluenesulphaminobenzenesulphonic acid obtained by this process may again be employed for the purpose of reacting with one-half molecule soda and 1 molecule nitrotoluenesulphonic chloride. The following compound is obtained—
—-NH—-SO_2—- —-NH—-SO_2—-
^ ^ ^ CH_3 ^
| | | | | | | |
| | | | | | | |
v v —-NH—-SO_2—- v v
SO_3Na CH_3 CH_3
If p-toluenesulphaminobenzenesulphonic chloride is condensed with sodium sulphanilide, a compound,
—-SO_2—-NH—- NaSO_3
^ ^ ^
| | | | | |
| | | | | |
v v —-SO_2—-NH—- v
SO_3Na