Production of aminonitrodihydroxyanthraquinones by partial reduction dinitrodihydroxyanthraquinones

The production of aminonitrodihydroxyanthraquinones of the formula: ##STR1## in which one X is OH and the other X is NO.sub.2 by partial reduction of the corresponding dinitrodihydroxyanthraquinone or mixtures thereof by heating at 80.degree.-250.degree. C in the presence of 1/2 to 5 times the weight thereof of an unsubstituted or substituted phenol. The reduction is accelerated by being carried out in the presence of a small amount such as 0.5-20 mol percent of an alkaline-reacting agent. Pure aminonitrohydroxyanthraquinones are obtained which are free from diaminodihydroxyanthraquinones.

The invention relates to a process for the production of 
aminonitrodihydroxyanthraquinones. 
It is known from Swiss Pat. No. 370,857 that dinitrodihydroxyanthraquinones 
can be selectively reduced with sodium hydrogen sulfide or sugars having a 
reducing action in an alkaline medium to give 
aminonitrodihydroxyanthraquinones. According to the disclosure in Japanese 
Patent Applications Nos. 8847/1963 and 21432/1969 the partial reduction 
can also be carried out with glucose in aqueous diethanolamine solution. 
We have found that an aminonitrodihydroxyanthraquinone of the formula (I): 
##STR2## 
in which one X is hydroxyl and the other X is nitro can be obtained in 
good yields and high purity by partial reduction of a 
dinitrodihydroxyanthraquinone by heating the dinitro compound in the 
presence of a phenol. 
The aminonitrodihydroxyanthraquinones obtained are free from 
diaminodihydroxyanthraquinones. The compounds (I) are important 
intermediates for the production of valuable disperse dyes. 
The phenol serves as a reducing agent in the process according to the 
invention. Phenol having no other substituents is preferred as the 
reducing agent; other phenols which may be used include those bearing 
alkyl of 1 to 4 carbon atoms, halogen, alkoxy of 1 to 4 carbon atoms 
and/or amino as substituents in the phenyl nucleus and phenols which have 
a higher basicity than unsubstituted phenol. Specific examples (in 
addition to phenol itself) are o-cresol, m-cresol, p-cresol, the xylenols, 
p-aminophenol, o-aminophenol, m-aminophenol, p-tert.-butylphenol, 
pyrogallol, resorcinol, hydroquinone, hydroquinone monomethyl ether and 
mixtures of the same. 
For economical and technical reasons phenol and the cresols are 
particularly preferred as reducing agents. 
The process according to the invention is either carried out in a large 
excess of the phenol serving as reducing agent and which thus serves at 
the same time as a solvent or in a solvent which is inert under the 
reaction conditions in the presence of a phenol. 
When the reduction is carried out in a phenol or mixture of phenols as 
solvent the amount of phenol is chosen so that the reaction mixture 
remains capable of being stirred before, during and after the reduction. 
As a rule the weight of phenol used is from 1.5 to 8 times that of the 
dinitrodihydroxyanthraquinone. No advantage is obtained by using a larger 
amount of phenol but there is the disadvantage that larger amounts of 
phenol have to be dealt with in the processing after the end of the 
reaction. For the sake of economy the amount of phenol used is preferably 
from 2.2 to 5 times that of the dinitro compound. 
When the partial reduction is carried out in a solvent suitable solvents 
are those which are inert under the reaction conditions or do not react in 
an undesirable way with the reactants and which have a boiling point which 
is higher than the desired reaction temperature. Examples of these are 
ethylene glycol, diethylene glycol, diethylene glycol monomethyl ether and 
monoethyl ether, N-methylpyrrolidone, N,N-dimethylformamide, 
o-dichlorobenzene, trichlorobenzene, nitrobenzene, naphthalene, the 
methylnaphthalenes and mixtures of the same. 
The amount of solvent used is as a rule from twice to ten times that of the 
dinitrodihydroxyanthraquinone. 
When the reduction is carried out in a solvent the amount of phenol used as 
reducing agent may be from half to five times and preferably from 0.8 to 
three times the weight of the dinitrodihydroxyanthraquinone. 
The reaction temperature depends mainly on the phenol used as reducing 
agent. The reduction is normally carried out at a temperature of from 
80.degree. to 250.degree. C and preferably at from 100.degree. to 
180.degree. C. When for example phenol is used as both solvent and 
reducing agent it is preferred to use the boiling temperature. The partial 
reduction is generally over after eight to eighteen hours under these 
conditions. 
The partial reduction can be accelerated by adding an alkaline agent. 
Examples of alkaline agents are: the alkali metal and alkaline earth metal 
hydroxides such as sodium hydroxide, potassium hydroxide, calcium 
hydroxide, barium hydroxide; the alkali metal carbonates and hydrogen 
carbonates such as potassium carbonate, sodium carbonate, potassium 
hydrogen carbonate, sodium hydrogen carbonate; alkali metal acetates such 
as sodium acetate and potassium acetate; alkali metal and alkaline earth 
metal phenolates such as potassium phenolate, sodium phenolate and calcium 
phenolate; aromatic nitrogen bases such as pyridine, the picolines, 
quinaldine and quinoline; secondary and tertiary aliphatic and 
cycloaliphatic amines such as tributylamine, dibutylamine, triethylamine, 
dicyclohexylamine and N-methylcyclohexylamine; dialkylanilines such as 
N,N-dimethylaniline; and saturated heterocyclic five-membered and 
six-membered heterocyclic bases such as piperidine, piperazine, 
morpholine, hexamethylenimine and thiomorpholine and mixtures of the same. 
For the sake of economy sodium carbonate, potassium carbonate, sodium 
hydrogen carbonate, sodium acetate, potassium hydrogen carbonate, 
pyridine, piperidine, quinoline, morpholine and/or tributylamine are used 
in particular. 
There is a clear acceleration of the reduction by adding only 0.5 mole% of 
alkaline agent, based on the dinitrodihydroxyanthraquinone. As a rule the 
amount of alkaline agent or mixture thereof used is from about 0.5 to 
20mole% and preferably from 3 to 10 mole%. There is no advantage in using 
a larger amount of the alkaline agent but rather the disadvantage that 
secondary reactions take place to an undesirable extent. 
When the alkaline-reacting agents which have a catalytic effect on the 
partial reduction are used, the reaction temperature is generally within 
the abovementioned temperature range. In many cases however it is possible 
depending on the reducing agent and alkaline agent used to carry out the 
reduction at a lower temperature than in the absence of an alkaline agent 
or at the same temperature within a shorter time. It is preferable to 
carry out the partial reduction at a temperature of from 100.degree. to 
180.degree. C. 
Thus for example in the partial reduction of a mixture of 
1,5-dinitro-4,8-dihydroxyanthraquinone and 
1,8-dinitro-4,5-dihydroxyanthraquinone in the presence of potassium 
carbonate as the alkaline agent and phenol as the reducing agent and 
solvent the best results are obtained at a temperature of from 110.degree. 
to 160.degree. C. 
In the presence of the alkaline agent the reaction is generally over after 
from one hour to twelve hours. 
The reaction may be monitored by means of thin layer chromatograms and the 
end of the reduction thus determined. 
The reduction mixture is generally processed by adding a diluent such as a 
low boiling point alcohol or a mixture of low boiling point alcohols with 
water which is miscible with the solvent used in the reduction and which 
has little or no solubility for the reduction product. Examples of low 
boiling point alcohols are ethanol, isopropanol, n-propanol, n-butanol, 
isobutanol and preferably methanol. 
The reduction product is precipitated upon dilution and can be isolated 
from the mixture by filtration. The filter residue is washed first with 
the diluent and then with water and if desired dried.

The following Examples will further illustrate the process according to the 
invention. The parts and percentages hereinafter given are by weight. 
Parts by volume bear the same relation to parts by weight as the liter to 
the kilogram. 
EXAMPLE 1 
16.5 parts of a mixture of 1,5-dinitro-4,8-dihydroxyanthraquinone and 
1,8-dinitro-4,5-dihydroxyanthraquinone (about 1:1 parts) is heated with 50 
parts of phenol for eight hours at 180.degree. C while stirring. After 
cooling 100 parts by volume of methanol is added, the precipitate is 
suction filtered and the residue is washed with methanol and then with hot 
water. After drying 13 parts of a mixture of 
1-amino-5-nitro-4,8-dihydroxyanthraquinone and 
1-amino-8-nitro-4,5-dihydroxyanthraquinone is obtained; this is equivalent 
to 87% of the calculated yield. 
EXAMPLE 2 
50 parts of phenol, 0.7 part of dry potassium carbonate and 16.5 parts of 
1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone (1:1 part) mixture is 
heated for nine hours at 130.degree. C. The reaction mixture is processed 
as described in Example 1. 10 parts of aminonitrodihydroxyanthraquinone is 
obtained. 
EXAMPLE 3 
16.5 parts of 1,5(1,7)-dinitro-4,8(4,5)-dihydroxyanthraquinone (0.8:1 part) 
is heated at 130.degree. C with 50 parts of phenol and 4.1 parts of 
anhydrous sodium acetate for fourteen hours. After processing as described 
in Example 1 8 parts of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 4 
16.5 parts of a mixture of 1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone 
(1:0.9 part) is added to a mixture of 50 parts of phenol and 0.6 part of 
anhydrous sodium carbonate at 70.degree. C while stirring. The mixture is 
heated for 3.5 hours at 150.degree. C and allowed to cool. 200 parts by 
volume of methanol is added and the precipitate is filtered off. The 
filter cake is washed with methanol, then with 0.5% sodium carbonate 
solution at from 50.degree. to 60.degree. C and finally with hot water. 
After drying 10 parts of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 5 
A mixture of 50 parts of phenol, 16.5 parts of 
1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone (1:1 part) mixture and 1 
part of tributylamine is heated for eleven hours while stirring at 
130.degree. C and for 3.5 hours at 150.degree. C. After cooling, 50 parts 
by volume of methanol is added. The precipitated reaction product is 
suction filtered, washed with 50 parts by volume of methanol and then with 
hot water and dried. 9 parts of aminonitrodihydroxyanthraquinone is 
obtained. 
EXAMPLE 6 
The procedure described in Example 4 is repeated but 0.5 part of sodium 
hydrogen carbonate is used instead of 0.6 part of anhydrous sodium 
carbonate. 10 parts of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 7 
The procedure described in Example 2 is repeated but only 0.35 parts of 
potassium carbonate is used. After processing an 
aminonitrodihydroxyanthraquinone is obtained which corresponds to that 
obtained according to Example 2. 
EXAMPLE 8 
16.5 parts of 1,5(1,8)-dinitro-4,8(4,5-dihydroxyanthraquinone mixture 
(1:0.9 part) is added while stirring to a mixture of 50 parts of p-cresol 
and 0.7 part of anhydrous potassium carbonate. The reaction mixture is 
heated for 4.5 hours at 125.degree. to 130.degree. C. The product is 
processed as described in Example 1. 12 parts (equivalent to 80% of the 
calculated yield) of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 9 
16.5 parts of 1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone mixture (1:1 
part) is heated in 50 parts of p-cresol for 1 hour at 145.degree. to 
150.degree. C and for 1 hour at 185.degree. to 190.degree. C. After 
processing as described in Example 1 9 parts of 
aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 10 
16.5 parts of 1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone mixture 
(1:0.8 part) is introduced into 50 parts of o-cresol and the whole is 
heated while stirring for 5.5 hours at 165.degree. to 170.degree. C. The 
reaction mixture is cooled and processed as described in Example 4. 10.5 
parts of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 11 
9.7 parts of p-aminophenol and 16.5 parts of 
1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone mixture (1:0.9 part) are 
heated in 50 parts by volume of o-dichlorobenzene while stirring for 4.5 
hours at 125.degree. to 130.degree. C. After standing overnight 2.5 parts 
of p-aminophenol is added and the reaction mixture is stirred again for 
3.5 hours at 130.degree. C. After cooling 200 parts by volume of methanol 
is added and the precipitated dye is filtered off. After the reaction 
product has been washed with methanol and hot water it is dried. 13 parts 
of a dye is obtained which consists predominantly of 
aminonitrodihydroxyanthraquinone. 
EXAMPLE 12 
33 parts of 1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone (1:1 part) and 
24 parts of p-aminophenol are heated in 100 parts by volume of 
nitrobenzene for 3.5 hours at 150.degree. C and for 1.5 hours at 
170.degree. C while stirring. After cooling the reaction product is 
precipitated with methanol, filtered off, washed with methanol and hot 
water and dried. 21 parts of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 13 
16.5 parts of 1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone (1:0.9 part) 
and 12.4 parts of hydroquinone monomethyl ether are heated in 100 parts by 
volume of methyl diglycol for 10 hours at 190.degree. C while stirring. 
After the reaction mixture has cooled it is poured into 500 parts by 
volume of 0.5% sodium carbonate solution and the reaction product is 
suction filtered, washed with water and dried. 11 parts of 
aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 14 
The procedure described in Example 13 is repeated but 11 parts of 
hydroquinone is used instead of 12.4 parts of hydroquinone monomethyl 
ether. 13 parts of aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 15 
16.5 parts of 1,5-dinitro-4,8-dihydroxyanthraquinone is added to a mixture 
of 50 parts of phenol and 0.35 part of anhydrous potassium carbonate which 
has been heated to 70.degree. C. The mixture is heated at 130.degree. C 
for thirteen hours while stirring. After processing as described in 
Example 4 8 parts of 1-amino-5-nitro-4,8-dihydroxyanthraquinone is 
obtained. 
EXAMPLE 16 
16.5 parts of 1,5(1,8)-dinitro-4,8(4,5)-dihydroxyanthraquinone mixture (1:1 
part) and 1 part of piperidine are heated in 50 parts of phenol for 18 
hours at 145.degree. to 150.degree. C. After the reaction mixture has been 
cooled to 60.degree. C 180 parts of methanol and 20 parts of water are 
added. The precipitated dye is filtered off, washed with methanol and 
water and dried. 15 parts of a dye is obtained which consists 
predominantly of aminonitrodihydroxyanthraquinone. 
EXAMPLE 17 
The procedure described in Example 16 is repeated but 1 part of pyridine is 
used instead of 1 part of piperidine. 15 parts of 
aminonitrodihydroxyanthraquinone is obtained. 
EXAMPLE 18 
8.25 parts of 1,8-dihydroxy-4,5-dinitroanthraquinone is heated in 40 parts 
of phenol in the presence of 1 part of morpholine for 3 hours at 
140.degree. to 150.degree. C. Then another 1 part of morpholine is added 
and the whole is heated for 1 hour at 150.degree. C. The reaction mixture 
is allowed to cool to 60.degree. C, 80 parts of methanol is added and the 
precipitated reaction product is suction filtered. The filter residue is 
washed with hot water and dried. 4.9 parts of 
1-amino-8-nitro-4,5-dihydroxyanthraquinone is obtained. 
EXAMPLE 19 
The procedure of Example 18 is repeated but using 1 part of 
N,N-dimethylaniline instead of 1 part of morpholine. The yield of 
1-amino-8-nitro-4,5-dihydroxyanthraquinone is 5.7 parts, equivalent to 76% 
of the calculated yield. 
EXAMPLE 20 
The procedure of Example 18 is repeated but 1 part of quinoline is used 
instead of 1 part of morpholine. The reaction is over after nine hours. 
After processing 6.0 parts of 1-amino-8-nitro-4,5-dihydroxyanthraquinone 
is obtained. 
EXAMPLE 21 
40 parts of resoreinol is heated to 150.degree. C and 8.25 parts of 
1,8-dinitro-4,5-dihydroxyanthraquinone is added. The reaction mixture is 
stirred for 1.5 hours at 150.degree. C, cooled to 60.degree. C and 120 
parts of methanol is added. The reduction product is thus precipitated. 
The precipitate is suction filtered and washed with methanol and hot 
water. The yield of 1-amino-8-nitro-4,5-dihydroxyanthraquinone after 
drying is 5.9 parts, i.e. 78.6% of the calculated yield. 
EXAMPLE 22 
50 parts of o-dichlorobenzene, 8.25 parts of 
1,8-dinitro-4,5-dihydroxyanthraquinone and 3.5 parts of pyrogallol are 
heated for 3 hours at 150.degree. C while stirring. Then 3.5 parts of 
pyrogallol is introduced and the reaction mixture is heated for another 7 
hours at 150.degree. C. After the reaction mixture has been cooled to 
60.degree. C it is diluted with 120 parts of methanol and cooled to 
ambient temperature. The precipitated reduction product is suction 
filtered, washed with methanol and hot water and dried. 5.3 parts of 
1-amino-8-nitro-4,5-dihydroxyanthraquinone is obtained.