A Method of Separating the Isomers contained in Crude Nitrotoluol..
Year: 1890

page_text: Date of Application, 27th Jan,
1890
Complete Specification Left, 13th Oct., 1890-Accepted, 15th Nov., 1890
PROVISIONAL SPECIFICATION.
A Method of Separating the Isomers contained in Crude Nitrotoluol..
I, Dr. MARTIN LANGE, of Amersfoort, Kingdom of Holland, Manufacturing
Chemist, do hereby declare the nature of this invention to be as follows:-
My invention is based on the difference in the action of sulphurating agents on
different nitrotoluols. It has been found by experiments that, in sulphurting
mixtures of orthonitrotoluol and paranitrotoluol, such as are present in crude nitro-.
toluol, at first the orthonitrotoluol only is sulphurated, while the paramitrotol tol
remains unattacked.
This difference of reaction I utilize in view of producing paranitrotoluol and ortho-
nitrotoluol-sulphonic acid from crude nitrotoluol, such as is to be had in the market.
For the said purpose 1 cause fuming sulphuric acid or sulphuric-acid-monochloro-
hydrine to run slowly into the mixture of the nitrotoluols while the temperature is
maintained at less than about 100° Centigrade. Sulphuric anhydride may, however,
also he employed. From time to time a sample of the substances under treatment is
examined by dissolving the same in water. When it is found that only paranitro-
toluol separates out in solid state, this is a proof that a sufficient quantity of the
sulphurating agent has been added and that this part of the operation is finished.
The product is thereupon poured into water, and the soluble portion is filtered off
from the paranitrotoluol which has separated out, or the latter is distilled off by
steam.
The nitrotoluol-sulphonic acid remaining in solution, is converted into solid form
by treating it with lime and evaporating down the calcium-salt obtained, or by other
known means.
Dotal th 07th day of Jan 1800
ERNEST DE PASS,
68, Fleet Street, London, Agent for the Applicant.
COMPLETE SPECIFICATION.
A Method of Separating the Isomers contained in Crude Nitrotoluol.
I, Dr. MARTIN LANGE, of Amersfoort, Kingdom of Holland, Manufacturing
Chemist, 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 :-
My invention is based on the difference in the action of sulphurating agents on
different nitrotoluols. It has been found by experiments that, in sulphurating mixtures
of orthonitrotoluol and paranitrotoluol, such as are present in crude nitrotoluol, at
first the orthonitrotoluol only is sulphurated, while the paranitrotoluol remains
unattacked.
This difference of reaction I utilize in view of producing paranitrotoluol and
orthonitrotoluol-sulphonic acid from crude nitrotoluol, such as is to be had in the
market. For the said purpose I cause fuming sulpburic acid or sulphuric-acid-mono-
chlorohydrine to run slowly into the mixture of the nitrotoluols while the temperature
is maintained at less than about 100° Centigrade. Sulphuric anhydride may,
however, also he employed. From time to time a sample of the substances under
treatment is examined by dissolving the same in water. When it is found that only
paranitrotoluol separates out in solid state, this is a proof that a sufficient quantity
of the sulphurating agent has been added and that this part of the operation is
finished.

page_text: The quantity of sulphuric anhydride or chlorohydrine required for the reaction
amounts to the equivalent of the orthonitrotoluol present.
Thereupon the product is poured into water, and the soluble portion is filtered off
from the paranitrotoluol which has separated out, or the latter is distilled off by
steam.
The nitrotoluol-sulphonic acid remaining in solution, is converted into solid form
by treating it with lime and evaporating down the calcium-salt obtained, or by other
known means.
Both substances, the orthonitrotoluol-sulphonic acid as well as the paranitrotoluol,
are valuable intermediate products in the preparation of dye-stuffs.
If for instance a crude nitrotoluol containing about equal parts orthonitrotoluol and
paranitrotoluol is to be treated, the following mode of operating is indicated.
274 lbs. of the said nitrotoluol are brought in dry state into an iron vessel and
400 lbs. of fuming sulphuric acid containing 20 per cent. of sulphuric anhydride, or
240 lbs. containing 33 per rent. of the latter, are run in thereto gradually, the vessel
being at the onset cooled. The sulphuration of the orthonitrotoluol goes on slowly,
to best advantage at a temperature between 50° and 100° Centigrade. At the end
of the operation the heat is raised and kept for some time at from 80° to 100°
Centigrade, whereupon the mass is caused to run into cold water. The paranitrotoluol
splits off in solid state and is separated by filtration, while the orthonitrotoluol-
sulphonic acid is obtained by treatment of the product of reaction with lime, or by
directly salting out the aqueous acid solution with common salt.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
The process of producing paranitrotoluol and orthonitrotoluol-sulphonic acid from
a mixture of paranitrotoluol and orthonitrotoluol, which consists in treating the said
mixture with a sulphurating agent, such a fuming sulphuric acid, sulphuric
anhydride or sulphuric-acid-chlorohydrine, the orthonitrotoluol being thereby con-
verted into orthonitrotoluol-sulphonic acid before the paranitrotoluol is acted upon,
substantially as described.
Did thin 12th day of On
2000
ERNEST DE PASS,
78, Fleet Street, London, Agent for the Applicant.