The Production of Phloroglucine.
Year: 1898

page_text: Date of Application
Complete Specification Left, 6th Oct., 1898-Accepted, 3rd Dec., 1898
The Production of Phloroglucine.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby
declare the nature of this invention (which has been communicated to me from
abroad by Leopold Cassella & Co., of Frankfort-on-Main, in the Empire of Germany,
Manufacturing Chemists), to be as follows:-
The troublesome and expensive methods of producing phloroglucine, have
hitherto prevented the technical use of this product. My correspondents have
found that this combination may be produced in a very simple manner and almost
quantitatively if salts of the easily obtainable 1.3.5-triamidobenzol or 1.2.4.6-
triamidobenzoic acid are heated with water for some time to 100° C. The same
result is obtained in a proportionately longer space of time, if the temperature at
which the reaction takes place is kept lower. Similar reactions have hitherto only
been made at higher temperatures and in the presence of free mineral acids or
salts. Owing to the instability of phloroglucine satisfactory results were not
obtained under such conditions.
This process is illustrated by the following example.
or
10 kilos. muriate 13.5-triamidobenzol an equivalent quantity of the
muriatic acid combination of 1.2.4.6-triamidobenzoic acid are dissolved in 150
litres water and boiled for 8 hours, with exclusion of air (; and preferably in the
presence of an indifferent gas:), in a vessel provided with a reflux apparatus.
The liquor is then concentrated to 30 litres and allowed to cool. The phloroglucine
which is formed, precipitates almost entirely and may be purified by recrystal-
lisation..
In the above example other mineral acid salts may be substituted for the muriates
of 1.3.5-triamidobenzol
The quantity of
or 1.2.4.6-triamidobenzoic acid.
water may be varied within fairly wide limits and the heating may take place in
closed as well as open vessels.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby
declare the nature of this invention (which has been communicated to me from
abroad by Leopold Cassella & Co., of Frankfort-on-Main, in the Empire of Germany,
CD 977

page_text: Manufacturing Chemists,) and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
The troublesome and expensive methods of producing phloroglucine, have
hitherto prevented the technical use of this product. My correspondents have
found that this combination may be produced in a very simple manner and almost
quantitatively if salts of the easily obtainable 1.3.5-triamidobenzol or 1.2.4.6-
triamidobenzoic acid are heated with water for some time to 100° C. The same
result is obtained in a proportionately longer space of time, if the temperature at
which the reaction takes place is kept lower. Similar reactions have hitherto only
been made at higher temperatures and in the presence of free mineral acids or
salts. Owing to the instability of phloroglucine satisfactory results were not
obtained under such conditions.
This process is illustrated by the following example.
-
10 kilos. muriate 1.3.5-triamidobenzol or an equivalent quantity of the
muriatic acid combination of 1.2.4.6-triamidobenzoic acid are dissolved in 150
litres water and boiled for 8 hours, with exclusion of air (; and preferably in the
presence of an indifferent gas:), in a vessel provided with a reflux apparatus.
The liquor is then concentrated to 30 litres and allowed to cool. The phloroglucine.
which is formed, precipitates almost entirely and may be purified by recrystal-
lisation.
In the above example other mineral acid salts may be substituted for the muriates
of 1.3.5-triamidobenzol or 1.2.4.6-triamidobenzoic acid. The quantity of
water may be varied within fairly wide limits and the heating may take place in
closed as well as open vessels.
The homologues also of phloroglucine may be produced in a similar way and in
a nearly theoretical yield, if the readily obtainable salts of 1-methyl-2.4.6-triamido-
benzene, of 1.3-dimethyl-2.4.6-triamidobenzene and of 1.3.5-trimethyl-2.4.6-triamido-
benzene are heated for some time with water to 100° in the manner above described.
The same result is obtained in a proportionately longer space of time if the tem-
perature at which the reaction takes place is kept lower. At a high temperature
or in presence of free mineral acids the homologues of phloroglucine cannot be
obtained owing to their instability.
Preparation of methylphloroglucine (1-methyl-2.4.6-trihydroxybenzene):
acetate
of
10 kilos. of the hydrochlorate of 1-methyl-2.4.6-triamidobenzene are dissolved
in 150 litres of water and are boiled in a vessel provided with the reflux apparatus
for 8-10 hours, the air being expelled by a current of carbonic acid. The solution
is then concentrated to a volume of about 30 litres and is extracted with amylalcohol,
which solvent takes up the whole of the phloroglucine. After having
driven over the amylalcohol with steam, the aqueous solution of
methylphloroglucine 18 partially precipitated with
lead in order to remove the coloured bye-products. The lead is precipitated from
the solution by the action of hydrogen sulphide. The filtered solution, which is
now nearly colourless, is concentrated in vacuo and yields the methylphloroglucine
in a pure state. This forms crusts consisting of needles which are readily soluble
in water and give a violet colour reaction when treated with ferric chloride. They
show a pine wood reaction similar to that of phloroglucine. Methylphloroglucine
melts between 215 and 216° C. When treated with alcohols and hydrochloric acid
it forms mono- and dialkylethers. It combines with aldehydes, amines and azocom-
pounds with formation of coloured products.
Preparation of dimethylphloroglucine (1.3-dimethyl-2.4.6-trihydrozybenzene); 5
10 kilos. of the hydrochlorate of 1.3-dimethyl-2.4.6-triamidobenzene, prepared in the
method described by Grevink (Ber. d. Deutschen Chem. Ges. 17. 2424) are dissolved
in 150 litres of water. This solution is boiled for 8-10 hours with the reversed
condenser with exclusion of air. The solution is concentrated to a volume of
about 30 litres and is then extracted with ether. Ether readily takes up the 5
dimethyltrihydroxybenzene and deposits it on evaporation in a nearly pure state.

page_text: For further purification the product is recrystallized several times from xylene.
From this solvent the dimethylphloroglucine separates in beautiful needles melting
at 163° C. Their aqueous solution gives with ferric chloride a red violet colour
reaction like phloroglucine itself, dimethylphloroglucine shows a pine wood re-
action which is however far more intensive and of a blue violet hue. From water
the dimethylphloroglucine separates with two molecules of water of crystallization.
When treated with alcohols and hydrochloric acid it yields only monalkylethers.
It reacts easily with aldehydes, phenols, amines and azo compounds.
Preparation of trimethylphloroglucine (trimethyl trihydroxybenzene) 1.3.5-tri-
methyl-2.4.6-trinitrobenzene forms contrary to the statement of Ladenburg
(Ann. 179. 176) by reduction with tin and hydrochloric acid, the hydrochlorate of
1.3.5-trimethyl-2.4.6-triamidobenzene, which on hydrolysis yields quantitatively
trimethylphloroglucine. The preparation is carried out in the following way;
10 kilos. of the hydrochlorate of 1.3.5-trimethyl-2.4.6-triamidobenzene are dis-
solved in 150 litres of water and are boiled for 8-10 hours with the reversed con-
denser with exclusion of air. The solution, when concentrated to a volume of
about 25 litres deposits on cooling the chief quantity of the trimethylphloroglucine
in plates of a light brown colour. The remaining part can be obtained by extract-
ing the mother liquor with ether. The crude product is purified by recrystallising
it from glacial acetic acid. Trimethylphloroglucine forms colourless needles, the
aqueous solution of which is coloured by ferric chloride first violet, then brown
violet, and in which an excess of ferric chloride causes a precipitate of a greyish
violet colour. It reduces silver nitrate. It shows no pine wood reaction and has
the melting point of 184° C. Trimethylphloroglucine as also its monoalkylethers,
which latter are formed by the action of alcohols and hydrochloric acid on this
phenol, combine readily with aldehydes, phenols, amines and azo-compounds.
In the before mentioned examples other salts of mineral acids may be used in-
stead of the hydrochlorates. The quantity of water employed may be varied within
wide limits and the heating may take place in open as well as closed vessels.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed (as communicated to
me from abroad) I declare that what I claim is:
1. The production of phloroglucine and its homologues by heating the mineral
salts of triamidobenzene, 1-methyl-2.4.6-triamidobenzene, 1.3-dimethyl-2.4.6-
triamidobenzene and of 1.3.5-trimethyl-2.4.6-triamidobenzene with water to a
temperature of about 100° or below.
2. As new products of manufacture: methylphloroglucine and dimethylphloro-
glucine.