Process for Converting Dialkylrhodamines into their Alkyl Esters.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Process for Converting Dialkylrhodamines into their Alkyl Esters.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in the
County of London, Chartered Patent Agent, do hereby declare the nature of
this invention (as communicated to me from abroad by Die Farbwerke vormals
Meister Lucius & Brüning, of Hoechst "/Main, in the Empire of Germany, Chemical
Manufacturers) to be as follows:-
My foreign correspondents have found that alphylsulphonic acid alkylesters,
such as, p-toluenesulpho-acid alkylesters, easily obtained from p-toluenesulpho-
chloride, or by other methods react readily with dialkyl-rhodamines. The pro-
duct of reaction thus resulting is completely insoluble in water, contrary to
the product resulting from the reaction of alkyl-sulphonic acid alkylesters upon
dialkylrhodamines: the former was therefore at first taken to be the p-toluene-
sulphodialkylrhodamide corresponding to the p-toluenesulphomonoethylamide, the
more so, as analogous to other acid esters, from a secondary amine and toluene-
sulphoacid ester, the acid amide ought to have resulted. In fact however the
product of reaction consists, of the p-toluenesulphonate of dialkylrhodamine
alkylester (rhodamine (G) which is insoluble in water: on treating it with
cold soda-lye the free ester may easily be obtained and from this the easily soluble
hydrochloride.
EXAMPLE I.
40 parts by weight of diethyl-rhodamine base and 20 parts by weight of p-
toluenesulphoacid methylester are heated to 100° C. for about 2 hours. The pro-
duct of reaction having become solid is finely pulverised and stirred with cold
soda-lye. The base thus set free, is filtered, washed with dilute soda-lye and
then transformed into the hydrochloride, which is freed from small quantities
of unchanged diethylrhodamine in the usual manner by treatment with sodium
acetate.
-
EXAMPLE II.
40 parts by weight of dimethyl-rhodamine base, 20 parts by weight of ethyl
benzenesulphonate are heated to 100° C. for about 2 hours; the further working
to produce rhodamine-ester is done as in Example I.
ABEL & IMRAY,
Agents for the Applicant.
Process for Converting Dialkylrhodamines into their Alkyl Esters.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in the
County of London, Chartered Patent Agent, do hereby declare the nature of
[Price 8d.]

page_text: this invention (as communicated to me from abroad by Die Farbwerke vormals
Meister Lucius & Brüning, of Hoechst /Main, in the Empire of Germany, Chemical
Manufacturers) and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:―
My foreign correspondents have found that alphylsulphonic acid alkylesters,
such as para-toluenesulphonic acid alkylesters, easily obtained from para-toluene-
sulphonic chloride, or by other methods, react readily with dialkylrhodamines.
The product of the reaction is completely insoluble in water, contrary to the
product of the reaction of alkylsulphonic acid alkylesters upon dialkylrhodamines;
the former was therefore at first supposed to be the para-toluenesulphodialkyl-
rhodamide corresponding with the para-toluenesulphomonoethylamide, the more so
as, analogously to other acid esters from a secondary amine and a toluenesulphonic
acid ester, the acid amide ought to have been produced. In fact, however, the
product of this reaction consists of the para-toluenesulphonate of dialkylrhod-
amine alkylester (rhodamine 6 G), which is insoluble in water: on treating it
with cold soda-lve the free ester may easily be obtained and from this the easily
soluble hydrochloride.
EXAMPLE I.
40 parts by weight of diethylrhodamine base and 20 parts by weight of para-
toluenesulphonic acid methylester are heated to 100° C. for about 2 hours. The
product of reaction having become solid is best treated in the following manner.
The pulverised mass is dissolved in alcohol and the solution is heated for some
time with addition of sodium acetate and is then filtered. The filtrate is poured
into water containing common salt, the precipitate is filtered and dissolved in
hot water to which is added some sodium acetate.
The dyestuff is precipitated from the solution with hydrochloric acid after
filtration from the small portions of the substance remaining insoluble.
EXAMPLE II.
40 parts by weight of dimethylrhodamine base and 20 parts by weight of
ethyl benzenesulphonate are heated together to 100° C. for about 2 hours; the
further treatment to produce rhodamineester is done as in Example I.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
The herein described process for transforming dialkylrhodamines into their
alkyl esters by heating the dialkylrhodamine bases with alphylsulphonic acid
alkyl esters.
Datel
J
1000
ABEL & IMRAY,
Agents for the Applicant.