Year: 1894

page_text: Date of Application, 23rd July, 1894
Complete Specification Left, 22nd Apr., 1895-Accepted, 24th May, 1895
I, OLIVER IMRAY, of No. 28, Southampton Buildings, Chancery Lane in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows :-
The a-naphtholdisulphonic acids 1. 4. 6 and 1. 4. 7 have hitherto been obtainable
only by boiling the corresponding naphthylamine disulphonic acids, Dahl's II
and III acids.
My foreign correspondents have found a new method of manufacturing these
acids which depends upon the sulphonation of a-naphtholcarbonate to tetrasulphonic
acids and upon the decomposition of the acids formed. This process on account of
its simplicity is to be regarded as a technical improvement.
The sulphonation of the carbonate to tetrasulphonic acids is effected by fuming
sulphuric acid at the ordinary temperature.
For this purpose 50 kilos. a-naphtholcarbonate are thoroughly stirred
into 250 kilos. fuming sulphuric acid containing 20% SO3; the carbonate dissolves
slowly and at first forms a nearly liquid melt, which, however, in the course of
about 12 hours, solidifies to a hard paste. This is a sign that the sulphonation has
reached the desired stage.
The
The melt is now poured into about 400 kilos. of ice-water, and the acid solution
thus diluted is heated to 60° to 70° C. until the effervescence ceases.
decomposition of the tetrasulphonic acid into carbonic acid and the naphthol
disulphonic acids 1. 4. 6 and 1. 4. 7 is thus completed.
The disulphonic acids are converted into the sodium salts by known methods,
and these are separated by the addition of salt to the solution.
The less soluble salt of the 1. 4. 7 acid is precipitated, that of the 1. 4. 6 acid
remains in solution, and this solution can be used directly for the manufacture of
colouring matters.
The 1. 4. 7 naphtholdisulphonic acid gives, on melting with caustic alkalies a
dioxynaphthaline sulphonic acid probably the, 1. 7 4. acid; by heating with dilute
acids under pressure one of the sulpho groups is eliminated, and the 1. 7 naphthol-
sulphonic acid results.
Doted this 3rd day of Into 1894-
ABEL & IMRAY,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Manufacture of the 1. 4. 6 and 1. 4. 7 a-Naphtholdisulphonic
Acids.
"
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:—
The a-naphtholdisulphonic acids 1. 4. 6 and 1. 4. 7 have hitherto been obtainable
only by boiling the corresponding naphthylamine disulphonic acids, Dahl's II
and III acids.
My foreign correspondents have found a new method of manufacturing these
acids which depends upon the sulphonation of a-naphthol carbonate to tetra
sulphonic acids and upon the decomposition of the acids formed. This process, on
account of its simplicity is to be regarded as a technical improvement.
The sulphonation of the carbonate to tetrasulphonic acids is effected by fuming
sulphuric acid at the ordinary temperature.
For this purpose 50 kilos. a-naphtholcarbonate
are thoroughly stirred
into 250 kilos. fuming sulphuric acid containing 20% SO, ; the carbonate dissolves
slowly and at first forms a nearly liquid melt, which, however, in the course of
about 12 hours, solidifies to a hard paste. This is a sign that the sulphonation has
reached the desired stage.
The melt is now introduced into about 400 kilos. of ice-water, and the acid
solution thus diluted is heated to from 60° to 70° C. until the effervescence ceases.
The decomposition of the tetrasulphonic acid into carbonic acid and the naphthol
disulphonic acids 1. 4. 6 and 1. 4. 7 is thus completed.
The disulphonic acids are converted into the sodium salts by known methods,
and these are separated by the addition of salt to the solution.
The less soluble salt of the 1. 4. 7 acid is precipitated, that of the 1. 4. 6 acid
remains in solution, and this solution can be used directly for the manufacture of
colouring matters.
The 1. 4. 7 naphtholdisulphonic acid gives, on melting with caustic alkalies, a
dioxynaphthaline sulphonic acid, probably the 1. 7. 4 acid; by heating with dilute
acids under pressure, one of the sulpho groups is eliminated, and the 1. 7 naphthol-
sulphonic acid results.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
Manufacture of the 1. 4. 6 and 1. 4. 7 a-naphtholdisulphonic acids by the
conversion of a-naphtholcarbonate by means of fuming sulphuric acid into
tetrasulphonic acids, the decomposition of these acids by heating with water and
the separation of the resulting a-naphtholdisulphonic acids by the addition
of salt.
Dated thin 00-118 A " 1005