Manufacture of Azoxy-compounds of the Aromatic Series.
Year: 1894

page_text: Date of Application, 24th Jan., 1894
Complete Specification Left, 22nd Oct., 1894-Accepted, 24th Nov., 1894
PROVISIONAL SPECIFICATION.
Manufacture of Azoxy-compounds of the Aromatic Series.
I, HANS LOESNER, Doctor of Philosophy, of 48, Windmüblenstrasse, Leipzig,
in the Kingdom of Saxony, do hereby declare the nature of this invention to be as
follows:-
The invention forming the subject of the present application consists in a process
for obtaining some azoxy compounds from the corresponding nitro-compounds by
reduction with arsenious acid in alkaline solution.
According to Woehler aniline is produced by the action of arseniates ou nitro-
benzene (v. Liebig's An. d. Chemie, vol. 102, p. 129), but hitherto the nature of
this process has not been elucidated. The aniline obtained by this process is only
a bye-product, because under any circumstances azoxy-benzene is formed as the
principal product of reduction.
The azoxy-compounds may be obtained in almost theoretical quantity, by
applying to the corresponding nitro-derivative the calculated quantity of the
reducing agent, as represented by the following equations;
OH
In the case of nitro-benzene,
in which R is a symbol for any aromatic radicle.
meta-nitro-benzoic acid, para-nitro-benzoic acid and meta-nitro-beuzene-sulpho-
acid, the reaction runs quite smoothly, but does not succeed in the case of ortho-
substitution compounds, such as ortho-nitro-toluene, ortho-nitro-benzoic acid, and
ortho nitro phenol.
EXAMPLES.
1. Fifty grammes of nitro-benzene are mixed with 60 grammes of arsenious
acid, 75 grammes of caustic soda (or 102 grammes of caustic potash) and about
600 parts of water and heated to the boiling point from 6 to 10 hours, while
constantly stirring. The azoxy-benzene thus produced is filtered and purified' by
recrystallization from alcohol.
2. Thirty grammes of nitro-benzoic acid are mixed with 30 grammes of arsenious
acid, 44 grammes of caustic soda (or 61 g. of caustic potash) and about 500 grammes
of water and the solution thus produced is heated to boiling point for about 5 hours,
subsequently the azoxy benzoic acid is precipitated by means of hydro-chloric
acid, filtered, and relieved of arsenic by digesting with dilute hydro-chloric acid.
The hitherto unknown para-azoxy-benzoic acid forms an amorphous faintly
coloured powder, which as regards its behaviour is quite analogous to the
corresponding meta-compound.

page_text: 3. 27 grammes of the meta-nitrobenzene-sulpho-salt of sodium or of potassium
are mixed with 18 grammes of arsenious acid, 24 grammes of caustic soda or the
corresponding quantity of caustic potash and 300 grammes of water, and heated
to the boiling point from 6 to 10 hours. Subsequently the arsenic is precipitated
as an arseniate with the calculated quantity of barium chloride or calcium chloride,
and then filtered, the filtrate is concentrated by evaporation to dryness, and the
sodium or potassium salt of the azoxy-benzene-sulpho-acid which has been formed
is purified by recrystallization.
Dated this 24th der of January 1801
COMPLETE SPECIFICATION.
Manufacture of Azoxy-compounds of the Aromatic Series.
I, HANS LOESNER, Doctor of Philosophy, of 48 Windmühlenstrasse, Leipzig,
in the Kingdom of Saxony, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The invention forming the subject of the present application consists in a process
for obtaining azoxy compounds from certain nitro-compounds by reduction with
arsenious acid in aqueous alkaline solution.
According to Woehler, aniline is produced by the action of arseniates on nitro-
benzene (v. Liebig's An. d. Chemie, vol. 102, p. 129), but hitherto the nature of
this process has not been elucidated. The aniline obtained by this process is only
a bye-product, because under any circumstances azoxy-benzene is formed as the
principal product of reduction.
The azoxy compounds may be obtained in almost theoretical quantity, by
applying to the corresponding nitro-derivative the calculated quantity of the
reducing agent, as represented by the following equations ;

page_text: 600 parts of water, and heated to the boiling point from 6 to 10 hours, while
constantly stirring. The azoxy-benzene thus produced is filtered and purified by
re-crystallisation from alcohol.
2. Thirty grammes of nitro-benzoic acid are mixed with 30 grammes of
arsenious acid, 44 gramines of caustic soda (or 61 g. of caustic potash) and about
500 grammes of water, and the solution thus produced is heated to boiling point
for about 5 hours, subsequently the azoxy benzoic acid is precipitated by means of
hydro-chloric acid, filtered, and relieved of arsenic by digesting with dilute
hydro-chloric acid.
The hitherto unknown para-azoxy-benzoic-acid forms an amorphous faintly
coloured powder, which as regards its behaviour is quite analogous to the
corresponding meta-compound.
3. 27 grammes of the meta-nitro-benzene-sulpho-salt of sodium or of potassium
are mixed with 18 grammes of arsenious acid, 24 grammes of caustic soda or the
corresponding quantity of caustic potash and 300 grammes of water, and heated to
the boiling point from 6 to 10 hours. Subsequently the arsenic is precipitated as
an arseniate with the calculated quantity of barium chloride or calcium chloride,
and then filtered, the filtrate is concentrated by evaporation to dryness, and the
sodium or potassium salt of the azoxy-benzene-sulpho-acid which has been formed
is purified by re-crystallisation.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The manufacture of azoxy-compounds of the aromatic series from nitro-
derivatives of the benzene series which do not contain any substituting group in
the ortho-position to the nitro-group, by heating the said nitro-derivatives with the
calculated quantity of arsenious acid in aqueous alkaline solution.
2. The manufacture of azoxy-compounds of the aromatic series from nitro-
benzene, m-nitro-benzoic acid, p-nitro-benzoic acid, and m-nitro-benzene-sulpho-
acid, in the manner substantially as described.
Dated this 18th day of October 1894.
FAIRFAX & WETTER,
433, Strand, London, Agents.