IMPROVEMENTS IN THE PREPARATION OF PURPLE COLOURING MATTERS SUITABLE FOR DYEING AND PRINTING
Year: 1884

page_text: I JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE PREPARATION OF PURPLE COLOURING MATTERS SUITABLE FOR DYEING AND
PRINTING" which Invention has been communicated to me from abroad by Heinrich
Caro, Chemist to the Badische Anilin and Soda Fabrik of Mannheim in the Empire
of Germany, to be as follows:-
This Invention relates to Improvements in the method of producing colouring
matters suitable for dyeing and Printing for which Letters Patent No 4428 were
granted to me (as a communication from Heinrich Caro of Mannheim Germany)
dated 15th September A.D. 1883.
In the Specification filed in pursuance of the said Letters Patent it is stated, that
chloride of zinc when employed in the place of chloride of aluminium to effect the
condensation between Oxychloride of Carbon and Dimethylaniline, or analogous
tertiary aromatic monamines produces inferior results as far as regards the yield of
colouring matter.
Now my foreign correspondent informs me that satisfactory results may be
obtained with the employment of chloride of zinc in the place of chloride of
aluminium by modifying the original process in the manner hereafter described.
The following example which refers to the synthetical preparation of crystallized
Methyl purple will serve to illustrate the manner of conducting the improved
process with the employment of chloride of zinc as a condensing agent.
About from eighteen to twenty parts by weight of oxychloride of carbon
(Phosgene) are gradually introduced into about one hundred parts by weight of
dimethylaniline at a temperature of about twenty degrees Centigrade and after the
space of about 24 hours about fifty parts by weight of, Dimethylaniline and about
thirty parts by weight of dry and finely powdered chloride of zinc are added. The
mixture thus obtained is then kept well agitated and about twenty parts by weight
of oxychloride of carbon are gradually added at a temperature of about from forty-

page_text: to fifty degrees Centigrade. By maintaining the temperature at about fifty degrees
Centigrade the operation will be finished within about six hours.
The colouring matter thus produced may then be separated by the methods
described in the Specification of the hereinbefore mentioned Letters Patent.
In order to effect a complete separation from chloride of zinc it is preferable to
produce first the well crystallizing sulphate of the Purple coloring matter. By the
addition of common salt to the hot solution of the sulphate a crystallisation of the
hydrochlorate, free from chloride of zinc may then be obtained.
In a similar manner purple colouring matters may be prepared by the action of
chloride of zinc and oxychloride of carbon upon dietbyleaniline, methyle-ethyle-
aniline and analogous tertiary aromatic monamines.
Date: Janas And 1001

page_text: I, JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of said Invention for "IMPROVEMENTS
IN THE PREPARATION OF PURPLE COLOURING MATTERS SUITABLE FOR DYEING AND
PRINTING" which invention has been communicated to me from Abroad by Heinrich
Caro, Chemist to the Badische Aniline and Soda Fabrik, Mannheime Germany and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
This Invention relates to improvements in the method of producing purple
coloring matters suitable for dyeing and printing for which Letters Patent dated
the 15th day of September A.D. 1883 and numbered No 4428 were granted to
Astley Paston Price (as a communication from the before named Heinrich Caro).
In the Specification filed in pursuance of the said Letters Patent it is stated that
chloride of zinc when employed in lieu of chlorido of Aluminium for the purpose
of effecting the condensation between Oxychloride of Carbon and Dimethylaniline
or analogous tertiary derivatives of Aniline-produces inferior results as far as
regards the yield of colouring matter.
Now my foreign Correspondent has found that satisfactory results may be
obtained with the employment of Chloride of Zinc in lieu of Chloride of Aluminium
by modifying the original process as described in the Specification of the said
former Letters Patent in the manner hereafter described.
The following example which refers to the synthetical preparation of "crystallized
Methylpurple" will serve to illustrate the manner of conducting the improved
process with the employment of Chloride of Zinc as a condensing Agent.
From eighteen to twenty parts by weight or thereabouts of Oxychloride of
Carbon (Phosgene) are gradually introduced into about one hundred parts by weight
of Dimethylaniline at a temperature of about twenty degrees Centigrade.
The supply of Oxychloride of Carbon which may be employed either in its
gaseous or in its liquified condition is to be regulated. in such a manner that the
temperature of the mixture does not rise considerably above thirty degrees
Centigrade. After the introduction of Oxychloride of Carbon the mixture is
allowed to stand at the ordinary temperature during the space of about twenty
four hours and then about fifty parts by weight of Dimethylaniline and about
thirty parts by weight of dry and finely powdered Chloride of Zinc are added.
The mixture thus obtained is then kept well agitated whilst a fresh supply of
Oxychloride of Carbon is gradually added at a temperature of about from forty to
fifty degrees Centigrade and in sufficient quantity to produce an increase of weight
of the mixture amounting to about twenty parts by weight. After the addition
of the Oxychloride of Carbon the temperature of the mixture is to be maintained
at about fifty degrees Centigrade during the space of about six hours in order to
complete the production of the colouring matter.
The separation of the Methylpurple thus produced may be effected by the
application of any known or suitable method. If it be desired to prepare its.

page_text: crystallized hydrochlorate practically free from Chloride of Zinc the result of the
operation as above described is supersaturated with caustic soda liquor and
submitted to a distillation with steam in order to obtain the base of the coloring
matter and to recover the excess of unchanged Dimethylaniline. The purple base
thus obtained (in admixture with hydrated oxide of zinc) is then separated from
the alkaline solution and converted into its well crystallisable sulphate which may
be further purified by recrystallization. By the addition of common salt to the hot
aqueous solution of the pure sulphate the Hydrochlorate of "crystallized Methyl
Purple" may finally be obtained in a pure and well crystallized condition.
Upon comparison of the foregoing example with the process described in the
Specification of the aforesaid prior Letters Patent it will become evident that the
herein before described improved process of operating with chloride of Zinc as a
condensing agent principally differs from the original process described in the said
Specification of the said prior Letters Patent by its being carried out in two
consecutive stages. In the first stage of the improved process oxychloride of
Carbon is allowed to react upon the tertiary derivative of Aniline without the aid
of the condensing agent and the result of such action is subsequently treated with
a fresh supply of the tertiary base and of Oxychloride of Carbon in the presence
of Chloride of Zine whilst in the process described in the Specification of the said
prior Letters Patent the colouring matters are produced by the joint action of
oxychloride of Carbon and of the condensing agent in a single and uninterrupted
operation.
In a similar manner an improved yield of purple colouring matters may be
obtained with the employment of Chloride of Zinc as a condensing agent by the
action of Oxychloride of Carbon upon Diethylaniline and Methylethylaniline. In
these instances however it has been found advantageous to assist the reaction in
the second or final stage of the process by the application of a somewhat higher
temperature say by heating the mixture from about eighty to one hundred degrees
Centigrade.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim is
The preparation or manufacture of purple coloring matters suitable for dyeing
and printing by treating Dimethylaniline, Diethylaniline or Methylethylaniline
with Oxychloride of Carbon and Chloride of Zine by the improved process
substantially as hereinbefore described.