IMPROVEMENTS IN THE PREPARATION OF ORGANIC BASES SUITABLE FOR THE MANUFACTURE OF DYE-STUFFS OR COLOURING MATTERS
Year: 1883

page_text: LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields in the
County of Middlesex Gentleman for an Invention of "IMPROVEMENTS IN
THE PREPARATION OF ORGANIC BASES SUITABLE FOR THE MANUFACTURE OF
DYE-STUFFS OR COLOURING MATTERS communicated to him from Alfred
Kern (Chemist) a person residing at Basle in Switzerland
"
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 19th November 1883.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN THE PREPARAȚION OF ORGANIC BASES SUITABLE
FOR THE MANUFACTURE OF DYE STUFFS OR COLOURING MATTERS a communication
from Alfred Kern (Chemist) a person residing at Basle in Switzerland
"
This Invention relates to the manufacture of dye stuffs or colouring matters of the
Rosaniline series and consists in the preparation of certain organic bases suitable
for being employed as auxiliary products in the said manufacture.
It is well known that Triphenylmethane the principal Hydrocarbon or Mother
substance of the Rosaniline series may be synthetically prepared by the condensation
of Benzhydral with Benzole.
It is likewise known that monamido-derivatives of Triphenylmethane may be
produced by an analogous condensation of Benzhydrol with aromatic amines such
as Aniline or Dimethylaniline
"
•
Moreover it is a well recognized rule that only such amido derivatives of
Triphenylmethane are leukobases" or compounds capable of being converted into
colouring matters of the Rosaniline series by oxydation in which at least two of
their three hydrocarbon residues are amidated. Starting from these known facts
my foreign correspondent has discovered that in order to produce the said
"leukobases" the requisite number of amidogroups may be introduced into the
molecule of Triphenylmethane and analogous hydro-carbons by employing certain

page_text: hydrolbases
or amidocompounds of Benzhydrol in the place of Benzhydrol in its
above named condensation with aromatic amines.
Now this Invention consists in a process or processes of producing the said
"hydrolbases" and of obtaining the said "leukobases" by their condensation with
certain primary secondary or tertiary Aromatic amines.
This Invention may be carried out as follows:-
1. PREPARATION OF THE HYDROLBASES.
The hydrolbases or amidoderivatives of Benzhydrol have before this never
received any industrial application. The general method of their preparation for
scientific purposes consists in the reduction of the corresponding "Ketone-bases"
or amidoderivatives of Benzophenane by means of Sodium amalgam-According to
the observations of my foreign correspondent the hydrol-bases may be prepared by
reducing their corresponding Ketone-bases with nascent hydrogen evolved from
zinc-dust and dilute hydrochloric Acid or by oxydizing their corresponding amido
derivatives of Diphenylmethane such for instance as Tetromethyl diamido-
diphenylmethane with the peroxides of lead or manganese in a manner analogous
to that now in use for the preparation of "Malachitegreen" from Tetramethyl-
diamido-triphenylmethane.
In practice the best results have been obtained by reducing the Ketone-bases in
Alcohol solution with zinc-dust and caustic alkalies. By preference a well dried
amyl-alcoholic solution of caustic soda is employed.
The following is an example of the manner in which the hydrolbases may be
prepared About one hundred parts by weight of Tetramethyl-diamido-benzo-
phenone are dissolved in about one thousand parts by weight of amylic alcohol
containing about sixty parts by weight of dry caustic soda in solution.
The Alkaline solution thus obtained is then heated with about eighty parts by
weight of zinc-dust at a temperature ranging from 120 to 130 degrees Centigrade
during about 48 hours or until the reaction no longer appears to proceed. This
point may be ascertained by withdrawing a sample of the said alkaline solution
from time to time and strongly acidifying the same by the addition of glacial
acetic acid whereby an intensely blue color will be developed. The reduction of
the Ketonbase may be considered to be finished if the said blue colour of the sample
no longer increases in intensity. The mixture is then allowed to settle and the
clear liquor is drawn off into a still in order to distill off the amylic alcohol which
may thus be recovered-The residue which is left behind in the still is then freed
from Alkali by repeated washings with water and afterwards dissolved in an excess
of cold and dilute hydrochloric Acid say in a mixture of about one hundred parts
by weight of strong hydrochloric Acid (of a specific gravity of about 1·18) with
two hundred and fifty parts of water. The acid solution thus obtained is then
filtered and the filtered liquor is mixed with about 1500 parts of water and
fractionally precipitated by the addition of caustic soda liquor in order to separate
the bydrolbase from any Ketonbase which may have remained unacted upon.
For this purpose caustic soda liquor is added until the solution has assumed a pure
blue color whereby a precipitate is formed containing the unaltered Ketonbase (if
any) The solution is then filtered and fully precipitated by adding Caustic Soda in
slight excess-The hydrolbase thus obtained is filtered free from alkali by washings
with water and pressed and it may then be dried at a temperature not exceeding
about 40 degrees Centigrade.
In a similar manner Tetraethyldiamido-benzhydrol-or analogous hydrolbases
may be prepared from their corresponding Ketone bases.

page_text: condensation differs from the analogous known action of Benzhydrol by the facility
with which it may be accomplished. There are neither high temperatures required
as in that instance nor the cooperation of energetic dehydrating Agents such as
phosphoric anbydride or chloride of Zinc. The hydrolbases and especially their
chlorhydrates or sulphates react upon a great number of aromatic amines already
at an ordinary temperature, and in a quicker and more complete manner at the
heat of the waterbath-The condensation may be effected either in aqueous
Alcoholic or in glacial acetic acid Solution according to the various degrees of
Solubility of the compounds employed. The Leukobases thus produced are separated
from their Acid solutions by the addition of caustic or carbonated Alkalies and may
be further purified by the employment of suitable solvents.
The hydrolbases which have hitherto yielded the best practical results are the
alkylized para-diamido compounds of Benzhydrol such for instance as Tetramethyl-
diamido benzhydrol
The aromatic amines which have proved capable of combining with the said
hydrolbases are either primary amines such as Aniline Orthotoluidine, Alpha
naphtylamine or their secondary and tertiary substitution-derivatives-No para-
amido compound has hitherto been found capable of undergoing the desired
condensation with the hydrolbases.
The manner in which the preparation of the leukobases of the Rosaniline series
may be effected and varied within the limits of this Invention is illustrated by the
following examples.
First. Condensation of a hydrolbase with a primary aromatic amine.
About twenty parts by weight of Tetramethyl-diamido-benzhydrol are dissolved
in about twelve parts by weight of strong hydrochloric Acid (of a specific gravity
of about 1:18) and about One hundred parts by weight or measure of water.
The solution thus obtained is then mixed with about ten parts by weight of
bydrochlorate of Aniline and heated on the water bath during about from 4 to
5 hours or until the reaction no longer appears to proceed
For organic bases contained in the result of the operation are then liberated by
the addition of Caustic soda liquor the excess of Aniline which has remained
unacted upon is distilled off by a current of steam and the Leukobase is separated
from the Alkaline liquor by filtration or otherwise. The leukobase thus obtained
is suitable for producing a purple colour by oxydation
Second-Condensation of a hydrolbase with a secondary aromatic amine
About twenty parts by weight of Tetramethyl diamidobenzhydrol are dissolved in
about twelve parts by weight of hydrochloric acid (of a specific gravity of about 1·18)
and about One hundred parts by measure of strong alcohol. Then a solution of
about thirteen parts by weight of benzylaniline in about eight parts by weight of
bydrochloric acid (of a specific gravity of about 1·18) and about fifty parts by measure
of strong alcohol is added and the mixture thus obtained is heated during from ten
to twelve hours on the water bath-In order to separate the leukobase thus
produced caustic soda liquor is added in excess the greater part of the alcohol is
distilled off, and the residue remaining in the still is completely precipitated by the
addition of water. The leukobase thus obtained is separated from the alkaline
liquor and may be further purified by the employment of suitable solvents such
for instance as benzole. It yields a bright blueish Purple by oxydation.
Third Condensation of a hydrolbase with a tertiary aromatic amine
Tetramethyl-diamidobenzhydrol obtained by the reduction of about one hundred
parts by weight of Tetramethyl-diamidobenzophenone in the manner above
described, is dissolved by preference in the state of a paste in about one hundred
and fifty parts by weight of diluted sulphuric acid containing about thirty parts
by weight of rectified sulphuric acid of a specific gravity of about 1-84. To the
solution thus obtained are then added about thirty parts by weight of dimethy-
laniline and the reaction is allowed to proceed, first at an ordinary temperature
during about twelve hours and afterwards at the heat of the waterbath during
about three hours or until the originally blue colour of the mixture has changed

page_text: into a pale greenish hue. This point being arrived at caustic soda liquor is added
in sufficient excess to liberate the organic bases contained in the said mixture and
then any dimethylaniline which may have remained unacted upon is recovered by
a distillation with steam. The contents of the still are then run off and allowed to
cool. The leukobase thus produced solidifies upon cooling and may be further
purified by crystallisation from suitable solvents, When submitted to the oxydising
action of peroxide of lead in the manner now in use for the above mentioned
preparation of Malachite green this leukobase is suitable for preparing a methylviolet
distinguished from the commercial Methylviolets hitherto known by its superior
brilliancy of colour and power of crystallization
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Patent Office on the 19th May 1884.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN THE PREPARATION OF ORGANIC BASES SUITABLE
FOR THE MANUFACTURE OF DYE STUFFS OR COLOURING MATTERS" a communication
to me from Alfred Kern Chemist a person residing at Basle in Switzerland
This Invention relates to the manufacture of Dye Stuffs or coloring matters of
the Rosaniline series and consists in the preparation of certain Organic bases
suitable for being employed as auxiliary products in the said manufacture.
It is well known that Triphenylmethane the principal Hydro carbon or Mother
substance of the Rosaniline series may be synthetically prepared by the
condensation of Benzhydrol with Benzole
.It is likewise known that monamido-derivatives of Triphenylmethane may be
produced by an analogous condensation of Benzhydrol with Aromatic amines such
as aniline or Dimethylaniline.
"
Moreover it is a well recognised rule that only such amido derivatives of
Triphenylmethane are "leukobases or compounds capable of being converted into
colouring matters of the Rosaniline-series by oxidation, in which at least two of
their three bydrocarbon residues are amidated, Starting from these known
facts my Foreign Correspondent has discovered that in order to produce the said
"leukobases" the requisite number of amidogroups may be introduced into the
molecule of Triphenylmethane and analogous hydrocarbons by employing certain
"hydrolbases or amidocompounds of Benzhydrol in the place of Benzhydrol in its
above named condensation with aromatic amines.
Now this Invention consists in a process or processes of producing the said
"bydrolbases" as hereinafter fully explained and of obtaining the said
"leukobases" by their condensation with certain primary secondary or tertiary
aromatic amines as also hereinafter more fully explained.
This Invention may be carried out as follows.

page_text: Scientific purposes consists in the reduction of the corresponding "Ketone-bases"
or amidoderivatives of Benzophenone by means of sodium amalgam... According
to the observations of my Foreign Correspondent the hydro-bases may be prepared
by reducing their corresponding Ketone-bases with nascent hydrogen evolved from
zinc dust and dilute hydrochloric acid or by oxydising their corresponding
amidoderivatives of Diphenylmethane such for instance as Tetramethyldiamido-
diphenylmethane with the peroxides of lead or manganese in a manner analogous
to that now in use for the preparation of "Malachitegreen" from Tetramethyl-
diamido-triphenylmethane.
In practice the best results have been obtained by reducing the Ketonebases in
alcoholic solution with zinc dust and caustic alkalies. By preference a well dried
amyl-alcoholic solution of caustic soda is employed.
The following is an example of the manner in which the hydrolbases may be
prepared-About one hundred parts by weight of Tetramethyl-diamido benzo-
phenone are dissolved in about one thousand parts by weight of amylic alcohol
containing about sixty parts by weight of dry caustic soda in solution.
The alkaline solution thus obtained is then heated with about eighty parts by
weight of zinc dust at a temperature ranging from 120 to 130 degrees centigrade
during about Forty-eight hours or until the reaction no longer appears to proceed
This point may be ascertained by withdrawing a sample of the said alkaline
solution from time to time and strongly acidifying the same by the addition of
glacial acetic acid whereby an intensely blue color will be developed Thé
reduction of the ketonebase may be considered to be finished if the said blue color
of the sample no longer increases in intensity The operation may likewise be
considered at an end if a sample of the alkaline alcoholic solution upon being
allowed to cool no longer separates out any appreciable quantity of the
unchanged ketonebase. The mixture is then allowed to settle and the clear liquor
is drawn off into a still in order to distil off the amylic alcohol which may thus be
recovered The residue which is left behind in the still is then free from alkali by
repeated washings with water and afterwards dissolved in an excess of cold and
dilute hydrochloric acid, say in a mixture of about One hundred parts by weight
of strong hydrochloric acid (of a specific gravity of about 1·18) with Two hundred
and fifty parts of water. The acid solution thus obtained is then filtered and the
filtered liquor is mixed with about Fifteen hundred parts of water and fractionally
precipitated by the addition of caustic soda liquor in order to separate the
hydrolbase from any ketonebase which may have remained unacted upon For
this purpose caustic soda liquor is added until the solution has assumed a pure blue
color whereby a precipitate is formed containing the unaltered ketonebase (if any)
The solution is then filtered and fully precipitated by adding caustic soda in slight
excess. The hydrolbase thus obtained is filtered free from alkali by washings with
water and pressed and it may then be dried at a temperature not exceeding about
forty degrees centigrade.
In a similar manner Tetraethyldiamidobenzhydrol or analogous tetraalkalised
diamido derivatives of Benzhydrol may be prepared from their corresponding
As above mentioned the preparation of leukobases of the Rosaniline series may
be effected by the condensation of the hydrolbases with certain primary secondary
or tertiary aromatic amines. The said condensation differs from the analogous
known action of Benzhydrol by the facility with which it may be accomplished.
There are neither high temperatures required as in that instance nor the
cooperation of energetic dehydrating agents such as phosphoric anhydride or
chloride of zinc. The hydrolbases and especially their chlorhydrates or sulphates
react upon a great number of aromatic amines already at an ordinary temperature
and in a quicker and more complete manner at the heat of the waterbath. The

page_text: condensation may be effected either in aqueous alcoholic or in glacial acetic acid
solution according to the various degrees of solubility of the compounds
employed The leukobases thus produced are separated from their acid solutions
by the addition of caustic or carbonated alkalies and may be further purified by
the employment of suitable solvents as is now well understood by Chemists.
The bydrolbases which have hitherto yielded the best practical results are
Tetramethyldiamidobenzhydrol and Tetraethyldiamido benzhydrol.
.
The aromatic amines which have proved capable of combining with the said
hydrolbases are the following-
I Primary Amines, Aniline, Orthotoluidine, Alpha-Naphthylamine.
II Secondary Amines. Methyl-aniline, Ethylaniline, Amylaniline, Benzylaniline
III Tertiary Amines, Dimethylaniline, Methyl Ethylaniline, Diethylaniline
Diamylaniline Dibenzylaniline, Methylbenzylaniline, Ethylbenzylaniline,
Amylbenzylaniline Methyldiphenylamine. Ethyldiphenylamine, Di-
methylorthotoluidine. Diethylorthotoluidine Dimethyl-Alpha, Naphthy-
lamine, Diethyl-Alpha Naphthylamine
The manner in which the preparation of the leukobases of the Rosaniline series
may be effected and varied within the limits of this Invention is illustrated by the
following examples.
First. Condensation of a hydrolbase with a primary aromatic amine.
About twenty parts by weight of the before mentioned Tetramethyl-diamido-
benzhydrol are dissolved in about twelve parts by weight of strong hydrochloric
acid (of a specific gravity of about 1·18) and about one hundred parts by weight
of water. The solution thus obtained is then mixed with about ten parts by weight
of hydrochlorate of aniline and heated at a temperature of about eighty degrees
centigrade during about from 4 to 5 hours or until the reaction no longer appears
to proceed. The organic bases contained in the result of the operation are then
liberated by the addition of caustic soda liquor, the excess of aniline which has
remained unacted upon is distilled off by a current of steam and the leukobase is
separated from the alkaline liquor by filtration or otherwise. The leukobase thus
obtained is suitable for producing a purple colour by oxidation
A similar result will be obtained by substituting Ortho-toluidine for aniline in
the before described process.
The following is an example of the manner in which a leukobase may be prepared
by the condensation of the above mentioned tetraalkalized Diamidoderivatives of
Benzhydrol with Alpha-Naphthylamine-About twenty parts by weight of Alpha-
Naphthylamine are dissolved in about four hundred parts by weight of strong
alcohol and to the solution thus obtained about sixteen parts by weight of hydro-
chloric acid (of a specific gravity of about 1.18.) and about forty parts by weight
of Tetramethyl-diamidobenzhydrol (previously mixed with or dissolved in about
One hundred and sixty parts by weight of strong alcohol) are added. The
mixture thus produced is then heated to ebullition during from three to four hours
when the conversion of the hydrolbase will be finished or nearly so. The reaction
however may likewise be accomplished at the ordinary temperature by allowing
the alcoholic mixture to stand for about twenty four hours. In order to separate
the new Leukobase thus produced the result of the operation may be treated as
follows. Caustic Soda liquor is added in strong excess, the greater part of the
alcohol is then recovered by distillation and the residue remaining in the still is
afterwards well washed with water dried and dissolved in hot beuzole when upon
cooling the leukobase will separate out in a purified condition. By the action of
suitable oxydizing agents (such for instance as chloranil) the said leukobase may be
converted into its corresponding colouring matter, which is a blue dye-stuff easily
soluble in alcohol but sparingly soluble in water.
Second, Condensation of a hydrolbase with a secondary aromatic amine.
About twenty parts by weight of Tetramethyl-diamidobenzhydrol are dissolved
in about twelve parts by weight of hydrochloric acid (of a specific gravity of
about 1·18) and about eighty parts by weight of strong alcohol. Then a solution

page_text: of about thirteen parts by weight of benzylaniline in about eight parts by weight
of hydrochloric acid (of a specific gravity of about 1-18) and about forty parts by
weight of strong alcohol is added and the mixture thus obtained is heated during
from ten to twelve hours in the water bath. In order to separate the leukobase
thus produced caustic soda liquor is added in excess the greater part of the alcohol
is distilled off and the residue remaining in the still is completely precipitated by
the addition of water. The leukobase thus obtained is separated from the alkaline
liquor and may be further purified by the employment of suitable solvents such
for instance as benzole. It yields a bright blueish purple by oxydation.
In an analogous manner leukobases capable of yielding purple or violet colouring
matters by oxydation may be obtained by heating an aqueous solution containing
Tetramethyl-(or Tetraethyl)-diamidobenzhydrol, hydrochloric acid and either
Methylaniline Ethylaniline or Amylaniline
Third. Condensation of a hydrolbase with a tertiary aromatic amine.
First example. Tetramethyl-diamidobenzhydrol obtained by the reduction of
about one hundred parts by weight of Tetramethyl-diamidobenzophenone in the
manner above described is dissolved (by preference in the state of a paste) in,
about one hundred and fifty parts by weight of diluted sulphuric acid and
containing about thirty parts by weight of diluted sulphuric acid of a specific,
gravity of about 1.84 To the solution thus obtained are then added about thirty
parts by weight of dimethylaniline and the reaction is allowed to proceed first at an
ordinary temperature during about twelve hours and afterwards at the heat of the
water bath during about three hours or until the originally blue colour of the
mixture has changed into a pale greenish hue. This point being arrived at caustic
soda liquor is added in sufficient excess to liberate the organic bases contained in
the said mixture and then any dimethylaniline which may have remained unacted
upon is recovered by a distillation with steam. The contents of the still are then
run off and allowed to cool. The leukobase thus produced solidifies upon cooling
and may be further purified by crystallization from benzole or other suitable
solvents. When submitted to the oxidising action of peroxide of lead (in the
Malachite green ")
manner now in use for the above mentioned preparation of
this leukobase is suitable for preparing a Methylviolet distinguished from the
commercial Methylviolets hitherto known by its superior brilliancy of colour and
power of crystallization.
In an analogous manner the condensation of Tetramethyl-(or Tetraetbyl—)
diamidobenzhydrol may be effected with Diethylaniline Diamylaniline Dimethyl-
orthotoluidine or with the other before named dialkalized substitution compounds
of Aniline or Orthotoluidine.
Second example-About ten parts by weight of Tetramethyl-diamido benzhydrol
are dissolved in about thirty two parts by weight of strong alcohol and then about
seven parts by weight of hydrochloric acid (of a specific gravity of about 1·18) and
about ten parts by weight of dibenzylaniline are added. The mixture or solution
thus obtained is afterwards digested at a temperature of about 70 degrees
centigrade during about three hours and then largely diluted with water in order
to precipitate any unchanged dibenzylaniline. The solution is filtered and
rendered strongly alkaline by the addition of caustic soda liquor and the leukobase
thus separated may then be filtered washed dried and further purified by treat-
ment with suitable solvents. It is suitable for producing a blueish-purple colouring
matter by oxydation.
In a similar manner the corresponding leukobases may be prepared by the
condensation of the before mentioned tetraalkalized diamido derivatives of
Benzhydrol with the above named tertiary Methyl-Ethyl or Amyl-substitution-
compounds of Benzylaniline and of Diphenylamine.
Third example. About ten parts by weight of Tetramethyl-diamidobenzhydrol
about six parts by weight of hydrochloric acid (of a specific gravity of about 1.18)
about fifty parts by weight of water and about ten parts by weight of Dimethyl-
Alpha-Naphthylamine are well mixed and heated at about eighty degrees centigrade

page_text: during the space of about six hours. The result of the operation is then rendered
strongly alkaline by the addition of caustic soda liquor and submitted to a
distillation with steam in order to volatilize and thus to recover any unchanged
Dimethyl-Alpha-Naphthylamine. The leukobase thus produced is capable of being
converted into á purplish-blue colouring matter by oxydation.
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is :-
First-The preparation of Tetramethyldiamidobenzhydrol and of Tetraethyl-
diamidobenzhydrol by reducing the corresponding Ketone-bases or (tetraalkalized
para diamido compounds of Benzophenone) in alcoholic solution with zinc dust and
caustic alkalies substantially as hereinbefore described.
Second-The preparation of "leukobases" (or amido compounds of Triphenyl-
methane and analogous hydrocarbons suitable for the manufacture of dye stuffs or
colouring matters) by the condensation of Tetramethyl-diamidobenzhydrol or of
Tetraethyldiamidobenzhydrol with the primary secondary or tertiary aromatic
amines herein before named and by the improved processes substantially as
herein before described
In witness whereof I the said John Henry Johnson have to this my Specification
set my hand and Seal this nineteenth day of May One thousand eight hundred
and eighty four.