vessel. The barium carbonate used in the process acts as a
contact substance, since the temperature at which the operation
is carried out is always above the decomposition point of
barium acetate. Crude acetone may be purified by converting
it into the crystalline sodium bisulphite compound, which
is separated by filtration and then distilled with sodium
CH3\ / OH CH3\
2 C + Na2CO3 = 2 CO + 2 Na2SO3 +
CH3/ \ SO3Na CH3/ CO2 + H2O
It is then dehydrated and redistilled.
Acetone is largely used in the manufacture of cordite
(q.v.) For this purpose the crude distillate is
redistilled over sulphuric acid and then fractionated.
Acetone is a colourless mobile liquid of pleasant smell,
boiling at 56.53 deg. C., and has a specific gravity 0.819
(0 deg. /4 deg. C.). It is readily soluble in water, alcohol,
ether, &c. In addition to its application in the cordite
industry it is used in the manufacture of chloroform (q.v.)
and sulphonal, and as a solvent. It forms a hydrazone
with phenyl hydrazine, and an oxime with hydroxylamine.
Reduction by sodium amalgam converts it into isopropyl
alcohol; oxidation by chromic acid gives carbon dioxide
and acetic acid. With ammonia it reacts to form di- and
triacetoneamines. It also unites directly with hydrocyanic
acid to form the nitrile of a-oxyisobutyric acid.
By the action of various reagents such as lime, caustic potash,
hydrochloric acid, &c., acetone is converted into condensation
products, mesityl oxide C6H10O, phorone C9H14O, &c., being
formed. On distillation with sulphuric acid, it is converted
into mesitylene C9H12 (symmetrical trimethyl benzene).
Acetone has also been used in the artificial production of
indigo. In the presence of iodine and an alkali it gives
iodoform. Acetone has been employed medicinally in cases of
dyspnoea. With potassium iodide, glycerin and water,
it forms the preparation spirone, which has been used as
a spray inhalation in paroxysmal sneezing and asthma.
ACETOPHENONE, or PHENYL-METHYL KETONE, C8H8O or
C6H5CO.CH3, in chemistry, the simplest representative of
the class of mixed aliphatic-aromatic ketones. It can be
prepared by distilling a mixture of dry calcium benzoate and
acetate, Ca(O2CC6H5)2 + (CH3CO2)2Ca = 2CaCO3 + 2
C6H5CO.CH3, or by condensing benzene with acetyl chloride
in the presence of anhydrous aluminium chloride (C. Friedel
and J. M. Crafts), C6H6+CH3COCl == HCl + C6H5COCH3.
It crystallizes in colourless plates melting at 20 deg. C. and
bolling at 202 deg. C.; it is insoluble in water, but readily
dissolves in the ordinary organic solvents. It is reduced by
nascent hydrogen to the secondary alcohol C6H5.CH.OH.CH3
phenyl-methyl-carbinol, and on oxidation forms benzoic
acid. On the addition of phenylhydrazine it gives a
phenylhydrazone, and with hydroxylamine furnishes an
C6H5\
C=N.OH
CH3/
melting at 59 deg. C. This oxime undergoes a peculiar rearrangement
when it is dissolved in ether and phosphorus pentachloride is
added to the ethereal solution, the excess of ether distilled
off and water added to the residue being converted into the
isomeric substance acetanilide, C6H5NHCOCH3, a behaviour
shown by many ketoximes and known as the Beckmann change (see
Berichte, 1886, 19, p. 988). With sodium ethylate in ethyl
acetate solution it forms the sodium derivative of benzoyl
acetone, from which benzoyl acetone, C6H5.CO.CH2.CO.CH3,
can be obtained by acidification with acetic acid. When
heated with the halogens, acetophenone is substituted in
the aliphatic portion of the nucleus; thus bromine gives
phenacyl bromide, C6H6CO.CH2Br. Numerous derivatives of
acetophenone have been prepared, one of the most important
being orthoaminoacetophenone, NH2.C6H4.CO.CH3, which
is obtained by boiling orthoaminophenylpropiolic acid with
water. It is a thick yellowish oil bolling between 242 deg.
C. and 250 deg. C. It condenses with acetone in the presence
of caustic soda to a quinoline. Acetonyl-aeeto phenone,
C6H5 . CO . CH2 . CH2. CO . CH3, is produced by
condensing phenacyl bromide with sodium acetoacetate with
subsequent elimination of carbon dioxide, and on dehydration
gives aa-phenyl-methyl-furfurane. Oxazoles (q.v.) are
produced on condensing phenacyl bromide with acid-amides (M.
Lewy, Berichte, 1887, 20, p. 2578). K. L. Paal has also
obtained pyrrol derivatives by condensing acetophenone-aceto-
acetic-ester with substances of the type NH2R.
ACETYLENE, klumene or ethine, a gaseous compound of
carbon and hydrogen, represented by the formula C2H2.
Physical properties.
It is a colourless gas, having a density of 0.92. When prepared
by the action of water upon calcium carbide, it has a very strong
and penetrating odour, but when it is thoroughly purified from
sulphuretted and phosphuretted hydrogen, which are invariably
present with it in minute traces, this extremely pungent odour
disappears, and the pure gas has a not unpleasant ethereal
smell. It can be condensed into the liquid state by cold
or by pressure, and experiments by G. Ansdell show that if
the gas be subjected to a pressure of 21.53 atmospheres at a
temperature of 0 deg. C., it is converted into the liquid state,
the pressure needed increasing with the rise of temperature,
and decreasing with the lowering of the temperature, until
at--82 deg. C. it becomes liquid under ordinary atmospheric
pressure. The critical point of the gas is 37 C., at which
temperature a pressure of 68 atmospheres is required for
liquefaction. The properties of liquid and solid acetylene
have been investigated by D. Mcintosh (Jour Chem. Soc.,
Abs., 1907, i. 458). A great future was expected from
its use in the liquid state, since a cylinder fitted with
the necessary reducing valves would supply the gas to light
a house for a considerable period, the liquid occupying
about 1/400 the volume of the gas, but in the United States
and on the continent of Europe, where liquefied acetylene
was made on the large scale, several fatal accidents
occurred owing to its explosion under not easily explained
conditions. As a result of these accidents M. P. E. Berthelot
and L. J. G. Vieille made a series of valuable researches
upon the explosion of acetylene under various conditions.
They found that if liquid acetylene in a steel bottle be
heated at one point by a platinum wire raised to a red heat,
the whole mass decomposes and gives rise to such tremendous
pressures that no cylinder would be able to withstand them.
These pressures varied from 71,000 to 100,000 lb. per square
inch. They, moreover, tried the effect of shock upon the
liquid, and found that the repeated dropping of the cylinder
from a height of nearly 20 feet upon a large steel anvil gave
no explosion, but that when the cylinder was crushed under
a heavy blow the impact was followed, after a short interval
of time, by an explosion which was manifestly due to the
fracture of the cylinder and the ignition of the escaping
gas, mixed with air, from sparks caused by the breaking of the
metal. A similar explosion will frequently follow the breaking
in the same way of a cylinder charged with hydrogen at a high
pressure. Continuing these experiments, they found that in
acetylene gas under ordinary pressures the decomposition
brought about in one portion of the gas, either by heat or the
firing in it of a small detonator, did not spread far beyond
the point at which the decomposition started, while if the
acetylene was compressed to a pressure of more than 30 lb. on
the square inch, the decomposition travelled throughout the
mass and became in reality detonation. These results showed
clearly that liquefied acetylene was far too dangerous for
general introduction for domestic purposes, since, although
the occasions would be rare in which the requisite temperature
to bring about detonation would be reached, still, if this
point were attained, the results would be of a most disastrous
character. The fact that several accidents had already
happened accentuated the risk, and in Great Britain the
storage and use of liquefied acetylene are prohibited.
When liquefied acetylene is allowed to escape from the cylinder
in which it is contained into ordinary atmospheric pressure,
some of the liquid assumes the gaseous condition with such
rapidity as to cool the remainder below the temperature
of -90 deg. C., and convert it into a solid snow-like mass.
Solubility of acetylene.
Acetylene is readily soluble in water, which at normal
temperature and pressure takes up a little more than its
own volume of the gas, and yields a solution giving a
purple-red precipitate with ammoniacal cuprous chloride and
a white precipitate with silver nitrate, these precipitates
consisting of acetylides of the metals. The solubility of
the gas in various liquids, as given by different observers,
100 Volumes of Volumes of Acetylene.
Brine absorb 5
Water '' 110
Alcohol '' 600
Paraffin '' 150
Carbon disulphide '' 100
Fusel oil '' 100
Benzene '' 400
Chloroform '' 400
Acetic acid '' 600
Acetone '' 2500
It will be seen from this table that where it is desired
to collect and keep acetylene over a liquid, brine, i.e.
water saturated with salt, is the best for the purpose, but
in practice it is found that, unless water is agitated with
acetylene, or the gas bubbled through, the top layer soon gets
saturated, and the gas then dissolves but slowly. The great
solubility of acetylene in acetone was pointed out by G. Claude
and A. Hess, who showed that acetone will absorb twenty-five
times its own volume of acetylene at a temperature of 15 deg. C.
under atmospheric pressure, and that, providing the temperature
is kept constant, the liquid acetone will go on absorbing
acetylene at the rate of twenty-five times its own volume for
every atmosphere of pressure to which the gas is subjected.
At first it seemed as if this discovery would do away with
all the troubles connected with the storage of acetylene
under pressure, but it was soon found that there were
serious difficulties still to be overcome. The chief
trouble was that acetone expands a small percentage of its
own volume while it is absorbing acetylene; therefore it is
impossible to fill a cylinder with acetone and then force
in acetylene, and still more impracticable only partly to
fill the cylinder with acetone, as in that case the space
above the liquid would be filled with acetylene under high
pressure, and would have all the disadvantages of a cylinder
containing compressed acetylene only. This difficulty
was overcome by first filling the cylinder with porous
briquettes and then soaking them with a fixed percentage of
acetone, so that after allowing for the space taken up by
the bricks the quantity of acetone soaked into the brick
will absorb ten times the normal volume of the cylinder in
acetylene for every atmosphere of pressure to which the gas
is subjected, whilst all danger of explosion is eliminated.
This fact having been fully demonstrated, acetylene dissolved
in this way was exempted from the Explosives Act, and
