Manufacture of Chlorindigo.
Year: 1899

page_text: Manufacture of Chlorindigo.
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:-
If ortho-chloro-ortho-nitrobenzaldehyde be treated with acetone or its equiva-
lents, such as pyruvic acid and acetaldehyde, and with alkalies, alkaline earths
or their carbonates, chlorindigo is obtained which is characterised by its tinctorial
properties. With chlorindigo far purer and more powerful tints are obtained
on wool or cotton than with natural or ordinary synthetic indigo.
Chlorindigo resembles ordinary indigo. It differs, however, from the latter
by greater solubility in organic solvents, being readily soluble, for instance,
in alcohol and ether. In cold sulphuric acid of 660 Bé specific gravity the
chlorindigo is soluble with a blue colour, in contrast with ordinary indigo,
which dissolves with a yellow-green colour, becoming blue only after standing
for some time or when, heated."
The ortho-chloro-ortho-nitrobenzaldehyde is obtained by successive chlorination,
bromination and oxidation of ortho-nitrotoluene. By chlorination is obtained
the ortho-chloro-ortho-nitrotoluene having the melting point 37° C. and from this
by bromination the ortho-chloro-ortho-nitrobenzyl-bromide having the melting
point 51-52° C. To transform the latter into ortho-chloro-ortho-nitroben-
zaldehyde the following method may be used:-
Ortho-chloro-ortho-nitrobenzyl-bromide is. transformed by hydrolysis with water
and chalk into ortho-chloro-ortho-nitrobenzyl alcohol. (melting point 59° C.)
which may be oxidised easily into aldehyde. To transform the bromide into
aldehyde it may also be treated with an aromatic amine or its sulphonic acid
and the resulting benzyl compound may be oxidised to the corresponding
benzylidene compound, from which ortho-chloro-ortho-nitrobenzaldehyde is then
obtained by decomposition with acids.
The ortho-chloro-ortho-nitrobenzaldehyde is very little soluble in water, easily
soluble in most organic solvents, less soluble in ligroin (melting point 70-70° C.).
The manufacture of chlorindigo is illustrated, by the following example:-
1 kilo of ortho-chloro-ortho-nitrobenzaldehyde is dissolved in 6 kilos. of acetone
and a solution of 1 per cent. of caustic soda is added by drops, the liquid being
cooled and stirred, till the appearing blue coloration indicates the formation of
indigo. The addition of caustic soda is then interrupted, while stirring is
continued for another 10 hours.
After that time the condensation product from chloronitroaldehyde and acetone
has almost completely separated in the form of crystals tinted blue by some
of the indigo, which has been produced at the same time. The product is separated
from the aqueous acetone by filtration and dissolved in little pure acetone.

page_text: This solution is slowly run, while stirring, into a solution of 12 litres of
caustic soda lye (40° Bé specific gravity in 100 litres of water.
The formation of chlorindigo begins at once; when no further increase is
observed in the quantity it is collected on a filter.
The chlorindigo is reduced more easily in the hydrosulphite vat than ordinary
indigo is and its vat yields, as already said, for more beautiful tints than that
of ordinary indigo. The chlorindigo-white appears to possess a greater affinity
for the fibre than has ordinary indigo.
TOU
T
1000
ABEL & IMRAY,
Agents for the Applicant.
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) and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-
If ortho-chloro-ortho-nitrobenzaldehyde be treated with acetone and with
alkalies or their carbonates or alkaline earths, chlorindigo is obtained which is
characterised by its tinctorial properties. With chlorindigo far purer and more
powerful tints are obtained on wool or cotton than with natural or ordinary
synthetic indigo.
.
Chlorindigo resembles ordinary indigo. It differs, however, from the latter
by greater solubility in organic solvents, being readily soluble, for instance,
in alcohol and ether. In cold sulphuric acid of 66° Bé specific gravity the
chlorindigo is soluble to a blue solution, in contrast with ordinary indigo, which
dissolves to a yellow-green solution, becoming blue only after standing for some
time or when heated.
The ortho-chloro-ortho-nitrobenzaldehyde is obtained by successive chlorination,
bromination and oxidation of ortho-nitrotoluene. By chlorination is obtained
the ortho-chloro-ortho-nitrotoluene having the melting point 37° C. and from this
by bromination the ortho-chloro-ortho-nitrobenzyl bromide having the melting
point 51-520 C. To transform the latter into ortho-chloro-ortho-nitroben-
zaldehyde the following method may be used:-
Ortho-chloro-ortho-nitrobenzyl bromide is transformed by hydrolysis with water
and chalk into ortho-chloro-ortho-nitrobenzyl alcohol (melting point 59° C.)
which may be oxidised easily into aldehyde. To transform the bromide into
aldehyde it may also be treated with an aromatic amine or its sulphonic acid
and the benzyl compound then produced may be oxidised to the corresponding
benzylidene compound, from which ortho-chloro-ortho-nitrobenzaldehyde is then
obtained by decomposition with acids.
The ortho-chloro-ortho-nitrobenzaldehyde (melting point 70-71°C.) is very
little soluble in water, easily soluble in most organic solvents, less soluble in
ligroin.
The manufacture of chlorindigo is illustrated by the following example:-
1 kilo of ortho-chloro-ortho-nitrobenzaldehyde is dissolved in 6 kilos. of acetone
and a solution of 1 per cent. of caustic soda is added by drops, the liquid being
cooled and stirred, till the appearance of a blue coloration indicates the formation

page_text: of indigo. The addition of caustic soda is then interrupted, while stirring is
continued for another 10 hours.
After that time the condensation product from chloronitroaldehyde and acetone
has almost completely separated in the form of crystals (melting point 134°.C.)
tinted blue by some of the indigo, which has been produced at the same time.
The product is separated from the aqueous acetone by filtration and dissolved
in a little pure acetone.
This solution is slowly run, while stirring, into a solution of 12 litres of
caustic soda lye (40° Bé specific gravity) in 100 litres of water.
The formation of chlorindigo begins at once; when no further increase is
observed in the quantity, the chlorindigo is collected on a filter.
The chlorindigo is reduced more easily in the hydrosulphite vat than ordinary.
indigo is and its vat yields, as already said, far more beautiful tints than that
of ordinary indigo. The chlorindigo-white appears to possess a greater affinity
for the fibre than has ordinary indigo.
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:-
1. The herein described manufacture of chlorindigo by subjecting ortho-chloro-
ortho-nitrobenzaldehyde mixed with acetone to the action of alkaline condensing
agents.
2. Ortho-chlorindigo manufactured as above set forth.