the Corresponding Amides.
Year: 1889

page_text: Date of Application, 1st Jan., 1889
Specification Accepted, 11th May 1389
the Corresponding Amides.
, ALBERT DENINGER. of 21 Hohestrasse, Dresden, Saxony, in the Empire of
Germany, Doctor, do hereby declare the nature of my said invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
This invention has for its object to effect improvements in the preparation of.
Nitro or Amido Phenols from the salts of the Amide whereby better results are
obtained than heretofore while greatly facilitating the formation of the Ortho or Para
compounds.
The process is as follows: The salts of the Amide are used in acid solutions, and
subjected to the treatment of Nitrous Acid, whereby three or more molecules of
nitrous acid unite with one amido group. The diazo compounds formed thereby are
then heated, which gives rise to the production of the required Nitrophenols. The
nitro-phenols thus prepared are reduced, by means of sulphuretted hydrogen, in an
alkaline solution, or by means of tin and hydrochloric acid, into Amido-phenols.
By rapidly heating the Diazo-compounds, the Ortho-compounds can advantageously
be produced with the Nitro-phenols, whereas by only slowly heating the same, or at
an ordinary temperature, the Para compounds can be readily obtained, so that where
several groups are possible, the preparation of the Ortho and Para compounds can be
easily carried out when required.
When three molecules of Nitrous acid are caused to act upon an aqueous solution of
sulphate of aniline, or of its homologous compounds, in such a manner that the
quantity of nitrous acid required for forming the Diazo is added slowly, and when the
Diazo is formed, the quantity of the same acid required for nitrous purposes is added
quickly, this nitrous acid being used in the form of nitrite of Soda or of gaseous
nitrous acid.
The product is then rapidly heated to 70° (, concentrated sulphuric acid having
been previously poured therein, when the Ortho-nitro phenol is readily produced from
the aniline; the former compound melts at 44° C, and composed of yellow acicular
crystals.

page_text: With Ortho-Toluidine are readily produced by rapid heating: Ortho Nitro cresol
with the groups (H³: OH NO in the positions of 1: 2: 3. This compound is
liquid, and its melting point is between 67° and 69° C; and by slow heating or at the
ordinary temperature. Para-Nitro creso! with the groups (H³ OH NO in the
positions of 1: 2: 5. This compound is not liquid and its melting point is 96° C.
With Para-Toluidine is readily produced: Para-Nitro-Cresol with the groups
CH³ N 02 OH in the positions of 1: 3: 4. This compound is liquid, its melting
point varies from 33° C. to 31° C; and it is used in preparing the corresponding
amide by means of sulphuretted Hydrogen in an alkaline solution, or by means of tin
and hydrochloric acid.'
:
If instead of using aniline, Napthylamine is employed, the corresponding Nitro
napthols are obtained from Napthylamine the Nitro napthol can be produced whose
melting point is 128°, and which is liquified with difficulty by means of steam,
6 molecules of nitrous acid should be caused to act upon one molecule of Benzidine and
Tolidine, in order to produce from the former Dinitrodiphenol, insoluble in water, but
soluble in Alcohol, Ether, Chloroform and glacial acetic acid. The Dinitrodiphenol
crystallises in small needles which are joined together in the form of balls; is
sublimated over 140° C, and melts while undergoing decomposition at about 260° C.
forming saits. In warm aqueous alkaline solution the Dinitrodiphenol is converted
by means of sulphuretted hydrogen into Diamido diphenol. The free bases are easily
decomposed. The salts formed by means of hydrochloric or sulphuric acid crystallise
in prisms and are soluble in water.
:-
the
The Dinitro dicresol produced from Ortho-Tolidine, forms a yellow mass like its
homologous Phenol and crystallises well from Pyridine. It is sublimated at a high
temperature and melts while undergoing decomposition at about 270° C.
The following example is given, showing the usual method of procedure:
60 gr of sulphuric acid.(crude sulphuric acid of commerce)tare mixed with
1 litre of water. After the liquor has cooled down, 250 gr of aniline are poured
therein. To obtain diazo compounds, the liquid must have a temperature of about
15° C. When this is attained, a.solution of 750 gr of nitrite of soda,in one litre of
water is added, in such a manner that the third part of the solution, that is to say,
quantity required for the formation of the diazo-compounds, is added slowly the
remainder being poured in quickly. After all the above substances have been added,
as much sulphuric acid is poured immediately in the liquor under constant stirring or
agitation until the latter has reached a temperature of at least 70° C. On account of
the froth a sufficiently large vessel should be used for these operations. The reaction
being terminated, the mass is allowed to cool and then is filtered. The black mass
distilled over with the aid of steam produces 60 per cent. of ortho nitrophenol. The
para nitrophenol is obtained from the residuum, by boiling with water, filtering when
hot and decomposing the solution with soda, so long as carbonic acid is evolved. By
subjecting the mass to the action of steam, sodic nitrophenol crystallizes. This last
compound is decomposed by means of hydrochloric acid, and the nitrophenol crystal-
lises out of the concentrated and-hot hydrochloric acid. The yield is 16 per cent. of
para nitro phenol.
In order to convert the nitrophenol into amidophenol, the following method
produces the best results. The nitrophenol is mixed with strong aqueous ammonia
and heated upon the water bath (on the "return flow" cooler), when a
strong stream
of sulphuretted hydrogen is admitted. When all the nitrophenol is reduced (which
can be ascertained owing to the liquor becoming lighter in colour) the same is steamed
on the water bath until dry-The-residuum is extracted with water by means of three
successive operations-Frour the sulphur filtrate separates the amido phenol in white
crystals.
The preparation of the other nitro or amido phenol is analogous to that above
described, when it is required to prepare its ortho compounds. For one molecule of
the amide, a little more than three molecules of nitrite of soda is required. The
quantity of sulphuric acid to be employed must obviously vary. The other articles
however remain the same. If in the amide operated upon, the para position is already.

page_text: filled as in Toluidine there is no need of heating with sulphuric acid. There is no
need whatsoever of heating-After a few weeks the whole of the dinitro-kresol
separates of its own accord.
When, on the contrary, para combinations are required, the diazo compounds are
formed at a temperature below 10° C. and the said compounds are allowed to
rest at a temperature of from 1° to 20° C. so long as a rod dipped therein does not
still cause when heated after its withdrawal therefrom an evolution of gas. The
duration of the self decomposition varies greatly. At 20° C. ten days are generally
sufficient particularly when the liquor is well stirred or shaken.
The yield varies greatly for the different substances. With benzidine and Tolidine
the theoretical quantity to be expected is almost entirely obtained. On the other hand
dinitro naphthols are easily produced from naphthylamines.
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 improved method of preparing nitro and amido-phenols from the corre-
sponding amides, by causing three or more molecules of nitrous acid to act upon an
acid solution of the salts of the amide of either of the aforesaid amido groups,
substantially as herein before described.
2. The improved method of preparing nitro-phenols from the diazo-compounds, by
slow or rapid heating, either as a para or an ortho-compound, substantially as
hereinbefore described.
3. The improved method of reducing the nitro-phenols, so as to obtain amido-
phenols, by means of an alkaline solution of sulphuretted hydrogen, substantially as
hereinbefore described.
4. The improved method of reducing the nitro-phenols, so as to obtain amido-
phenols, by means of tin and hydrochloric acid, substantially as hereinbefore
described.
1000