IMPROVEMENTS IN THE MANUFACTURE OF THE HYDROCARBURETS OF COAL TAR, AND OF THE AMINES DERIVED THEREFROM
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by William Edward Gedge at the Office
of the Commissioners of Patents on the 30th December 1876. A communi-
cation from abroad by Léon Hiernaux, of Vilvorde, Belgium, Engineer.
WILLIAM EDWARD GEDGE, of No. 11, Wellington Street, Strand, in the County
of Middlesex, Patent Agent. "IMPROVEMENTS IN THE MANUFACTURE OF THE
HYDROCARBURETS OF COAL TAR, AND OF THE AMINES DERIVED THEREFROM."
communication from abroad by Léon Hiernaux, of Vilvorde, Belgium, Engineer.
A
The object of this Invention is specially the manufacture in an economical
manner of the amines obtained from coal, particularly aniline C H7 az toluidine C7
H az and so on, and their compounds, matters which have become so valuable,
particularly for dyeing.
To facilitate the description of this Invention I will take for example aniline;
its actual manufacture is to treat coal tar by fractional and repeated distillations,
in order to extract therefrom the benzene C He which with concentrated and heated
azotic acid gives mononitro benzene,
C® H® + H N O³ = Cª H³ (N O³) + H³ O.
..
H)
This nascent H come from various sources of manufacture (bydrosulphuret of
ammonia, iron with acetic acid, zinc with hydrochloric acid, and others etc.); this
process of manufacture is very faulty.
In the first place by fractional distillations, but very little benzene can be
extracted from coal tar, and then only by a very long and expensive treatment.
Further, to pass from benzene to aniline a very dear compound is used, namely, azotic
acid which does not regenerate, and finally it is necessary to reduce again by nascent
hydrogen.
The process which forms the object of this Invention is much to be preferred; it
is based on the following points :-The hydrocarburets of coal tar are formed of two

page_text: elements or parts C and H (carbon and hydrogen) the centesimal proportions of
which are extremely varied. As a same cause cannot produce different results this
diversity of composition is due to the diversity or varying conditions of temperature,
of pressure of proportions, etcetera, of the carbon and hydrogen at the moment of
their combination, and even when already combined. Now it has been ascertained
by experiment that these carburets of hydrogen may pass from one to the other by
hydrogenization or by hydrogenizations. Thus in treating benzene, Cª Ho, by
nascent hydrogen H, more hydrogerated hydrocarburets may be obtained, C7 H³,
toluene C8H10, xylene, and other products, according to the respective quantities of
the elements in presence of each other, and the practical conditions of the reaction.
Further, various hydrocarburets heated together in a closed vessel, and at a very
high temperature combine, transform, and give birth to other hydrocarburets of
more stability, and the composition of which depends on that of the mixture. On
the other hand to pass from benzenc, C" H", to aniline, C H' az, it is needless to use
the intermediary of nitrification with ulterior reduction.
The direct reaction of the benzene with the ammonia az H³ at very high temper-
ature and pressure immediately produces aniline,
C Haz H³ = C® H7 + H⁹.
This H (hydrogen) which disengages does not remain inactive, the hydrogen, the
hydrocarburet, or the amine are already formed, but it may be employed in a very
preferable way as herein-after described.
In short by this Invention aniline may be manufactured directly and with great
economy, by heating together in a closed vessel coal tar and ainmonia, but it requires
practical conditions, proper proportions, and uniformity of mixture, temperature,
pressure, and duration of the reaction.
The operation will begin by depriving the coal tar of the ammoniacal waters it
holds imprisoned in its pores, and subsequently of its acid matters by the ordinary
alkaline treatment. It will therefore now contain only its neutral hydrocarburets,
and some alkaloids which need not be eliminated because they aro amines ready
formed. This tar will be analyzed and the respective quantities of C and H therein
will be ascertained. These quantities are nearly always approximatively equal, so
that if all C were united to all H there would sensibly be benzine CH. It must
however be borne in mind that the nature of coal tar is exceedingly variable,
according to the quality of the coal, and the conditions of the distillation; these
quantities may naturally be regulated because a more or less hydrogenated hydro-
carburet may be added to obtain the desired proportion between the carbon C and
the hydrogen H. The proper proportions once obtained, the mixture very uniform
(constant stirring of the mass), the temperature, pressure, and the duration of the
reaction sufficient, there is a unification of the hydrocarburets. The C and the H
have a tendency to separate, like the H and the O in the separation of the
water H2O, (the repulsive force of the heat overcoming the affinity of the elements).
When they are more or less in this state of indifference the mixture being very
uniform the temperature is lowered, and the result is a single compound, the stability
of which will be very great, and the composition of which will depend upon that
of the mixture.
To manufacture the aniline benzene will be produced, which will then react upon
the az H³
CH+az H³ = CH'az + H*
As regards this H which is disengaged in this reaction it will be utilized to
hydrogenate the hydrocarburets of the tar, and in view of this fact the mixture
will be made so that there may be an excess of carbon, which excess this hydrogen
will destroy.
It will be evident that according to the proportions of the elements, either
toluidine may be produced C7 HP az or xylidine CH az, and so on, but not so easily
as aniline, for benzene is the typical hydrocarburet of coal tar the most stable of
the aromatic series. Further for dyeing it is almost as advantageous to have mixtures

page_text: of amine as puro amines; the separation of the various amines is in all cases
perfectly realizable.
It might be desired to manufacture not amines but only the aromatic hydro-
carburets, benzene, toluene, and similar products; in such case it is only necessary
5 to employ ammonia.