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the hydrogen of the hydroxyls.

Hydroxylamine hydrochloride is dissolved in 8 10 parts
of water, together with an equivalent amount of sodium car-
bonate, and 3 parts of benzoyl chloride gradually added, the
whole being then well shaken up and cooled; the dibenz-
hydroxamic acid separates out together with a portion of the
benzhydroxarnic acid, which is removed by recrystallization
from hot alcohol. The benzhydroxarnic acid remaining in the
solution is precipitated by barium chloride, and then liberated
from the well-washed precipitate by dilute sulphuric acid. A
further quantity of it can be obtained, since dibenzhydroxamic
acid splits up into benzoic acid and benzhydroxarnic acid when
heated with baryta water.

Bcnzhydroxamic acid or Benzenyloximic acid, C 6 H 5 .C(OH)NOH,
crystallizes in rhombic plates or tablets, and dissolves in 44'5
parts of water at 6, much more readily in tolerably warm water,
very readily in alcohol and slightly in ether. It has an acid
reaction, melts at 124 125, and undergoes a sudden, violent
decomposition at a higher temperature. When heated with dilute
hydrochloric acid, it decomposes into hydroxylamine and benzoic
acid. It is monobasic, but forms acid salts with the alkali metals.

Acid potassium lenzhydroxamate, C 6 H 5 .C(OH)NOK + C 6 H 3 .C
(OH)NOH, is tolerably soluble in cold water, scarcely in alcohol,
and crystallizes in small rhombic plates or flat, pointed prisms,
which deflagrate sometimes with the production of flame, when
heated. The normal salt is readily soluble in alcohol ; on
evaporation of the solution, however, the acid salt and potassium
carbonate separate out.

Acid sodium benzhydroxamate, C 6 H 5 .C(OH)NONa + C 6 H 5 .C
(OH)NOH + 3H 2 O, is somewhat more readily soluble in water,
slightly in alcohol, and crystallizes in long, thin plates, or large
elongated tablets, which rapidly deliquesce in the air.

Acid barium hydroxamate, (C 7 H 6 N0 2 ) 2 Ba+C 7 H 7 NO 2 , forms
small prisms scarcely soluble in water and alcohol.

Normal barium hydroxamate, (C 7 H 6 N0 2 ) 2 Ba, is ootained by
the addition of barium chloride to a solution of the acid
potassium salt which has been treated with ammonia ; it forms
microscopic needles. The calcium salt is a precipitate resembling
alumina ; the benzhydroxamates of most of the other metals are
also insoluble.

The behaviour of the acid and its acid salts towards ferric



DIBENZHYDROXAMTC ACID. 209

chloride is very characteristic ; a dark red precipitate is formed
which dissolves in an excess of the precipitant with a deep
cherry-red colour, which is not altered by the addition of dilute
hydrochloric or sulphuric acid, but is destroyed by concentrated
hydrochloric acid ; the addition of water causes the reappearance
of the colour. If the original solution contains hydrochloric
acid, ferric chloride only produces a colouration.

When the barium salt is distilled with a little water aniline is
formed : l

2(C H 5 C(OH)NO) 2 Ba + H. 2 O = 2C 6 H 5 .NH 2 + C0 2 + BaCO 3 .

Ethyl bcnzkydroxamate, C 6 H 5 .C(OH)OC 2 H 5 , is obtained by the
action of ethyl iodide and caustic potash on a solution of the
acid in alcohol, 2 as well as by that of benzoyl chloride on ethyl
hydroxylamine, H 2 N(OC 2 H 5 ). 3 It is very slightly soluble in
water, readily in alcohol, and crystallizes in thick tablets, which
melt at 64 65 and are resolved at 190 into alcohol, aldehyde,
benzamide and phenyl isocyanate. It is readily soluble in
alkalis, being re-precipitated from solution by acids and even by
carbon dioxide ; on heating with concentrated hydrochloric acid,
it decomposes into benzoic acid and ethyl hydroxylamine. If
equal molecules of the ether and caustic potash be dissolved in
alcohol and treated with silver nitrate, a white precipitate
of C (5 H 5 .C(OAg)NOC 2 H 5 , is obtained, which blackens only on
heating, while silver benzhydroxamate blackens and decomposes
immediately on precipitation.

Benzoyl cthylbcnzhydroxamate, or Bcnzethylbcnzliydroxylamine,
H 5 .C(O.CO.C 6 H 5 )NOC 2 H 5 , is obtained by the action of benzoyl
chloride on an alkaline solution of the ether ; it is readily soluble
in alcohol and ether and forms transparent rhombic crystals,
melting at 48 49. 4

2119 Dibenzhydroxamic acid, or Benzoylbenzoximic acid, C 6 H 5 .C
(OH)NO.CO.C 6 H 5 , which is produced by the action of benzoyl
chloride on benzhydroxamic acid, crystallizes from hot alcohol in
needles, and on the spontaneous evaporation of the solution in
large, lustrous, rhombic prisms ; it has an acid reaction, melts at
153 , 5 and decomposes violently at a higher temperature with
formation of carbon dioxide, benzoic acid, benzanilide and phenyl
isocyanatc. On heating with hydrochloric acid it splits up into

1 Ann. CJicm. Phai~m. clxxv. 323. - Waldstein, ibid, clxxxi. 384.

:! (iiirke, ibid. ccv. 278. 4 Pieper, ibid, cexvii. 8.

5 Steincr, ibid, clxxviii. 22G. 6 Pieschel, ibid, clxxv. 305.
VOL. III. PART IV. P



210 AROMATIC COMPOUNDS.

benzole acid and hydroxylamine, while alkalis decompose it into
benzhydroxamic acid and benzoic acid, so that the former acid
can be prepared from it by means of baryta water. Its alkali
salts on the other hand are decomposed by water even in the cold,
more rapidly on heating, with formation of benzoic acid, carbon
dioxide and diphenyl urea :



NO.GO.C 6 H 6



2C 6 H 5 .CO.OK



X N(C 6 H 5 )H
C0( + CO,

\N(C 6 H 5 )H



As already mentioned, benzhydroxamic acid cm be directly
converted into aniline, while dibenzhydroxamic acid yields
derivatives of this phenyl isocyanate, benzanilide and diphenyl
urea from which aniline can easily be obtained. Since the
homologues of benzoic acid also yield oximes, a general method
is established by which the carboxyl of a monobasic aromatic
acid can be replaced by an amido-group (Lessen).

Inversely, the amido-group of amido-compounds can be re-
placed by carboxyl, and aniline thus converted into benzoic acid
(Part III. p. 35).

Potassium dibenzhydroxam-ate, C 6 H 5 .C(OK)NO.CO.C 6 H 5 , is
precipitated in thin plates when alcoholic solutions of the acid
and caustic potash are mixed. If silver nitrate be added to its
freshly prepared aqueous solution, a white precipitate of the
silver salt is obtained ; if this be dried, covered with ether and
treated with ethyl iodide, the ethyl ether is obtained in two
isomeric forms, one of which is an oily substance, 1 while the
other is dimorphous.

a-Ethy', dibenzhydroxamate, C 6 H 5 .C(OC 2 H 5 )NO.CO.C 6 H 6 , is
the chief product of the reaction; it is readily soluble in ether
and alcohol, and crystallizes in four- or eight-sided rhombic
prisms, melting at 58.

P-Ethyl dibenzhydroxamatf., which is only formed in very small
quantity, is more readily soluble than the a-compound and forms
triclinic crystals, melting at G:>.

These modifications cannot be directly converted into each

1 Eiseler, Ann. Chcm. Pharm. clxxv. 326 ; Giirke, ibid. ccv. 279.






TRIBENZHYDROXYLAMINE. 211

other ; on heating they decompose into benzonitril, aldehyde and
benzoic acid :

C 6 H 5 .C(OC 2 H 5 )NO.CO.C 6 H 5 = C 6 H 5 .CN + C 2 H 4 O +
C 6 H 5 CO.OH.

Concentrated hydrochloric acid decomposes them into benzoic
acid, ethyl benzoate and hydroxylamine, while on heating with
caustic potash, benzoic acid and two isomeric ethylhydroxamic
acids are formed.

The oily ether is also readily soluble in alcohol and ether,
and behaves chemically like the two others ; it is only formed in
small quantity and has not been closely investigated.

a-FAhylbenzhy'droxamic acid, C 6 H 5 .C(OC 2 H 5 )NOH, is readily
soluble in alcohol and ether ; it crystallizes from a mixture of
ether and benzene in monoclinic tablets or prisms, melting at 53'5.

The ethyl ether, C 6 H 5 .C(OC. 2 H 5 )NOC 2 H 5 , is formed by the
action of ethyl iodide on a solution of the acid in alcoholic
potash. 1 It is a powerfully refractive liquid which has a
pleasant aromatic odour, and boils at 244 with slight decom-
position ; its vapour has a sp. gr. of 6'56 (Giirke). On heating
with alcohol and hydrochloric acid, it forms ethyl benzoate
and ethyl hydroxylamine.

ft-Ethylhydroxamic acid is isomorphous with the a-compound,
but it melts at 67'5 68, is more soluble in petroleum spirit,
less so in caustic potash, and is more readily extracted from
this by ether. Its ethyl ether is so similar to that of the
a-compound that it is doubtful whether they are distinct
substances.

Both acids are formed simultaneously by the action of
hydroxylamine on benzimido-ethyl ether. 2

It is almost completely converted into ethyl /3-dibenzhydroxa-
mate by the action of benzoyl chloride. 3

2 1 20 Tribenzhydroxylamine, or Dibcnzolenzoxiiqate, C 6 H 5 .C
(O.CO.C 6 H 5 )NO.CO.C 6 H 5 , is obtained in three modifications by
treating dry hydroxylamine hydrochloride with a solution of
benzoyl chloride in toluene, or by heating potassium dibenz-
hydroxamate with benzoyl chloride. 4 It is, however, best

1 Lessen and Zanni, Ann. Chem. Pharm. clxxxii. 220.
" Lessen, Ber. Deulsch. Chem. Ges. xvii. 1587.

3 Giirke, Ann. Chem. Pharm. ccv. 281.

4 Lessen, Ann. Chem. Pharm. clxi. 360 ; clxxv. 282 ; clxxxvi. 34 : Steincr,
ibid, clxxviii. 225.

P 2



212 AEOMATIC COMPOUNDS.

prepared by acting upon silver dibenzhydroxamate with a solution
of benzoyl chloride in petroleum ether, and allowing the whole
to stand until the silver chloride has separated as a dense
precipitate (Lossen).

a-Tribenzhydroxylamine is slightly soluble in cold, more
readily in hot alcohol and ether, and forms monoclinic crystals,
elongated in the direction of the ortho-diagonal, 1 which melt at
100. It is completely split up into benzoic acid and dibenz-
hydroxamic acid by heating for an hour with hydrochloric acid
of sp. gr. 1-05.

ft-Tribcnzhydroxylamine is insoluble in ether, slightly soluble
in cold, more readily in hot alcohol, and forms small, lustrous,
monoclinic crystals, melting at 141 142 (Klein and Trech-
mann). It is decomposed by concentrated hydrochloric acid at
150 into benzoic acid, dibenzhydroxamic acid and hydroxyl-
amine.

ry-Tribenzhydroxylamine is only formed in small quantity; it
crystallizes in short, monoclinic prisms, melting at 112, and is
to a large extent converted into the yS-compound by dilute
hydrochloric acid.

All the three modifications are resolved on dry distillation
:*nto benzoic anhydride and phenyl isocyanate :



' = C 6 H 5 NCO+(CO.C 6 H 5 ) 2 0.

They are decomposed by alcoholic potash into dibenzhydrox-
amic acid and benzoic acid.

The chemical behaviour of these substances is therefore iden-
tical, and they present an instance of trimorphism, for although
they all crystallize in forms belonging to the monoclinic system,
these forms are distinct ones and cannot be derived from one
another.

Benzenylamidoxime, or Bcnzhydroxamide, C 6 H 5 .C(NOH)NH 2
is formed when a solution of hydroxylamine and benzonitril in
dilute alcohol is heated to 80 for about eighteen hours : 2

C 6 H 5 .CEEN +H,N.OH = C 6 H 5 C.

JNHg.

1 Klein and Trechmann, Ann. Chem. Pharm. clxxxvi. 104.

2 Kruger and Tieraann, Bcr. Dcutsch. Chem. Gcs. xvii. 126. 1687 ; xviii. 727,
1053.



BENZHYDROXAMIDE. 213

It is also formed by the action of hydroxylamine on benz-
amidine, C 6 H 5 .C(NH)NH 2 , and was described by Pinner as
benzoxamidine.

It is readily soluble in alcohol and ether, and crystallizes from
hot water in long, flat, acute prisms, melting at 79 80. It is
precipitated by petroleum spirit from its solution in benzene in
needles. Its solution is coloured deep red by ferric chloride ; it
forms salts both with acids and bases. Benzamide and nitrous
oxide are formed by the action of sodium nitrite on its hydro-
chloride, while when heated to 200 with hydrochloric acid, it
decomposes into ammonium chloride and benzoic acid.

Benzenylamidoxime is poisonous ; thus, 0'5 grm. proved fatal
to a dog, O'l grm. to a rabbit, and 0'03 grm. to a frog.

Its alkyl ethers are formed by heating the sodium salt with
the corresponding iodide.

Ethyl ether of benzenylamidoxime, C 6 H 5 .C(NOC 2 H 5 )NH 2 , is
almost insoluble in water, but readily soluble in alcohol and
ether, and crystallizes in rhombic plates, which melt at 67, and
dissolve in acids but not in alkalis. Its hydrochloride crystal-
lizes well.

Benzcnylethoxime chloride, C 6 H 5 .C(NOC H 5 )C1, is formed when
sodium nitrite is added to a well-cooled solution of the ether :



HC1 + NaNO 9 = C 6 H 5 .C(NOC 2 H 5 )OH

NaCl + H0 + N.



C C H 5 .C(NOC 2 H 5 )OH + HC1 = C 6 H 5 (NOC 2 H 5 )C1 + H 2 O.

According to Lessen, a diazo-compound is probably formed at
first, and then decomposes in the following manner : *

X>NOC 2 H 5
HC1 = C 6 H 5 .C r + N 2 + H 2 O.



The chloride is also readily produced by the action of phosphorus
pentachloride on ethyl benzhydroxamate, C 6 H 5 .C(NOC 2 H 5 )OH. 2
It is an oily, aromatic liquid, which boils at 239, is not decom-
posed by water or alcohol, and is not even attacked when heated
for a short time with acids and alkalis. When heated with
alcoholic ammonia to 160 180, however, the amidoxime ethyl
o.ther is re-formed, and it is converted by the action of a

1 Bcr. Dcutech. Chcm. Gcs. xviii. 1193.
- Ibid.



214 AROMATIC COMPOUNDS.

solution of sodium in absolute alcohol into ethyl ethylbenz-
hydroxamate.

Bcnzoylbenzenylamidoxime, C 6 H 5 .C(NO.CO.C 6 H 5 )NH 2 , is
formed by the action of benzoyl chloride on benzenylamidoxime.
It crystallizes in fine, white needles, which melt at 140, and
are soluble in alcohol, ether, and acids, but not in alkalis.

2 121 Dibenzenylazoxime, (C 7 H 5 ) 2 N.jO, is obtained by heating
the compound just described beyond its melting-point, or by
treating it with dehydrating agents, such as benzoic anhydride
or benzoyl chloride :



NO.CO.C 6 H 5



5 + H 2 0.



It is scarcely soluble in water, but readily in alcohol, and
crystallizes in long, fine needles, which, after drying, resemble
asbestos and melt at 108, but sublime at a much lower
temperature.

Ethenylbenzenylazoxime is formed by the action of acetic anhy-
dride on benzenylamidoxime, and is very similar to the preceding
compound, crystallizing in needles which readily sublime, have a
characteristic odour and melt at 41. It is isomeric with benz-
enylethenylazoxime, which is obtained by the action of benzoyl
chloride on ethenylamidoxime, CH 3 .C(NOH)NH 2 , and forms
aromatic needles, which melt at 57 and sublime very easily. 1
The isomerism of these two compounds is shown by the follow-
ing formulae :

Ethenylbenzenylazoxime. Benzenylethenylazoxime.

,NO X ,* N 0\

C 6 H 5 .C^ ^ \C.CH 3 CH 3 .C^ ^ \C.C 6 H,

Acetylbenzenylamidoxime, C 6 H 5 .C(NO.CO.CH 3 )NH 2 , is formed
by the action of acetyl chloride on an ethereal solution of benz-
enylamidoxime. It crystallizes from alcohol in small plates or
flat prisms, which melt at 96, and are easily converted into
ethenylbenzenylazoxime, the change being brought about even
by boiling with water. 2
Ethyl lenzenylamidoximecarloxylate, C 6 H 6 .C(NH2)NO.CO.OC 2 H 5)

1 Nordmann, Bcr. Deutsch. Chem. Gcs. xv. 2754.
- Schultz, ibid, xviii. 1080.



BENZENYLAZOXIME CARBINOL. 215

is obtained by adding ethyl chlorocarbonate to a solution of
benzenylamidoxime in chloroform. It crystallizes in long,
lustrous needles, which melt at 127 and are decomposed at a
higher temperature, or on heating with water, into the following
compound, alcohol being removed :

Bcntenylazwime ccirlinol, C 8 H 6 N .,("). is most simply prepared
by heating benzenylamidoxime with ether chloroformate. It
crystallizes from hot water in long needles, melting at 197.
It readily dissolves in alkalis; its aqueous solution has an acid
reaction and decomposes the carbonates of the alkaline earth
metals. Silver nitrate precipitates the white crystalline silver
salt from a solution neutralized with ammonia, and copper sul-
phate, the green copper salt, (CgHgNgO^Cu.

According to the method by which it is prepared, benzenyl-
azoxime carbinol should have the first of the following formulae ;
its whole behaviour, however, corresponds with the second, and
an intramolecular change must therefore be assumed :



C 6 H 5 .C^ ^>CO C 6 H,C^_ ^C.OH.

Carbonyldibenzenylamidoxime, (C 6 H 5 .C(NH 2 )NO) 2 CO, is formed
when benzenylamidoxime is brought into contact with carbonyl
chloride dissolved in benzene. It is almost insoluble in the
latter and is precipitated by water from its alcoholic solution
in small plates, melting at 128 129. On heating with
caustic soda solution, the preceding compound is formed. 1

Benzenylazoxime propenylcarboocylic acid, C U H 10 N 2 O 3 , is ob-
tained by heating benzenylamidoxime with succinic andydride :

^N.OH CH 2 -CO,
^NH, "*" CH.CO/

C c H v cf ^C CH CH, CO.OH + H 2 O.

\ N = /

It crystallizes from hot water in small, lustrous, white, rhombic
plates or prisms, melting at 1 20.

The anhydrides of other dibasic acids give similar compounds.' 2

1 Falck, Her. Dculm-h. Chr.m. Ges. xviii. 2467-

2 Sdiultz, ibid, xviii. 2458.



216 AROMATIC COMPOUNDS.

Metanitrobcnzenylamidoxime, C 6 H 4 (NO 2 )C(NH 2 )NOH. Meta-
nitrobenzonitril readily combines with hydroxylamine to form
this compound. It crystallizes in orange-coloured prisms, melt-
ing at 174. A series of compounds has been prepared from it,
corresponding to those described above. 1

Metamidobenzenylamidoxiine, C H 4 (NH 2 )C(NH 2 )NOH, is
formed by the reduction of the preceding compound, and
separates from ether as a yellow oil which gradually solidifies.
Its hydrochloride, C 6 H 4 (NH 3 C1)C(NH 3 C1)NOH, crystallizes
from hot water in prisms.

Metahydroxybenzenylamidoxime, C 6 H 4 (OH)C(NH 2 )NOH, has
been prepared from the amido-compound by the diazo-reaction,
and crystallizes from dilute alcohol in light yellow needles, melt-
ing at 163 . 2



HALOGEN-SUBSTITUTION PRODUCTS OF
BENZOIC ACID.

2122 When an atom of hydrogen in benzole acid is replaced
by an element of the chlorine group, a meta-compound is formed,
and not, as in the case of toluene and the benzyl compounds, a
para-compound, accompanied by a small amount of an ortho-
compound.

Substituted benzoic acids are obtained by the oxidation of the
corresponding alcohols and aldehydes, as well as of the substitu-
tion products of toluene and such other compounds as are them-
selves readily oxidized to benzoic acid.

They may also be obtained from the amidobenzoic acids by
means of the diazo-reaction. The old method, proposed by
Griess, consisted in heating a diazo- amidobenzoic acid with
hydrochloric, hydrobromic, or hydrofluoric acid :

N.NH.C H 4 .CO H

> HC1 = NH 2 .C 6 H 4 .CO.,H + C 6 H 4 C1.CO,H + N 2 .
NC 6 H 4 .C0 2 H

He subsequently found that the sulphates of the diazobenzoic
acids are more suitable for the purpose ; one part is boiled
with 3 to 5 parts of the hydracid, the substituted benzoic acid

1 SchSpff, Bcr. Deutsch. Chcm. Gcs. xviii. 1063. 2 Ibid, xviii. 2472.



ORTHOCHLOROBENZOIC ACID. 217

separating out on cooling as a mass of crystals. Hydriodic
acid acts in this way oven in the cold : *



|| + HI = C H 4 I.CO,H + S0 4 H 2 + N 9 .

NS0 4 H

A reaction which possesses considerable theoretical interest
has been employed for the preparation of these compounds by v.
Richter. When paranitrochlorobenzene or paranitrobromobenzene
is heated with alcohol and potassium cyanide, the nitroxyl group
is replaced by hydrogen, and the cyanogen group takes the
meta-position, the nitnl of metachloro- or metabromobenzoic
acid being formed, while metanitrochlorobenzene is converted
into orthochlorobenzoyl chloride. Orthonitrochlorobenzene and
orthonitrobromobenzene, on the other hand, are not attacked by
potassium cyanide. 2

The halogen-substitution products are readily converted into
benzoic acid by the action of sodium amalgam and water.



MONOCHLOROBENZOIC ACIDS, C 6 H 4 C1.C0 2 H.

2122 Orthocldorobenzoic acid was obtained by Chiozzain 1852,
by heating salicylic acid (orthohydroxybenzoic acid) with phos-
phorus pentachloride, and decomposing the fraction of the dis-
tillate boiling between 200 250 with water. 3 It was believed
to be identical with the chlorobenzoic acid which is formed by
the direct chlorination of benzoic acid, until Limpricht and Uslar,
as well as Kolbe and Lautemann, showed that the latter compound
is a distinct substance, and gave it a distinctive name, chloro-
salylic acid.* Kekule obtained the ortho- acid in a similar
manner from wintergreen oil, which consists chiefly of methyl
salicylate. 5

Its formation will be discussed under salicylic acid. In order
to prepare it, an intimate mixture of one molecule of sodium
salicylate with two molecules of phosphorus pentachloride is
distilled, the portion boiling above 240 separated, and de-
composed by boiling caustic soda solution, the acid being then
precipitated by hydrochloric acid (Kolbe and Lautemann).
The precipitate is dissolved in the smallest possible quantity of

1 Her. Dcutsch. Chcm. Gca. xviii. 060. - Ibid. iv. 459.

3 Ann. Chcm. Phnrm Ixxxiii. 317. 4 Ibid. cxv. 183. 5 Ibid, cxvii. 145.



218 AROMATIC COMPOUNDS.

boiling water and treated with a slight excess of weak milk of
lime ; calcium salicylate is thus formed and separates completely
when the solution is well stirred and heated on the water-bath
for some hours. The filtrate is precipitated with hydrochloric
acid, and the orthochlorobenzoic acid purified by re-crystallization
from boiling water. 1 The mixture of acids can also be separated
by distillation with steam, with which salicylic acid a! one vola-
tilizes. 2

Pure salicylic acid may be substituted for the sodium salicylate. 3
According to Glutz, it is better to employ wintergreen oil, to
which the phosphorus pentachloride must be gradually added,
the mixture heated for a considerable time until hydrochloric
acid ceases to be evolved, and then distilled and treated as
above. 4

Orthochlorobenzoic acid is also formed when orthochloro-
toluene is boiled with a dilute solution of potassium perman-
ganate. 5 It dissolves in 881 parts of water at 0, is readily
soluble in hot water and alcohol, and crystallizes in long, silky
needles, which melt at 137, and sublime in lustrous crystals.
It melts when heated with a little water, in the same manner as
benzoic acid. When heated to 200 with caustic potash, it
yields 10 per cent, of salicylic acid and 20 per cent, of meta-
hydroxybenzoic acid, equal quantities being formed when caustic
soda is employed (Ost).

Calcium orthochlorolenzoate, (C 7 H 4 C10 2 ) 2 Ca + 2H 2 O, crystallizes
in prisms, which are very slightly soluble in alcohol, but very
readily in water. The solution of the acid in ammonia is there-
fore not precipitated by calcium chloride, and it may thus be
distinguished from its isomerides.

Orthochlorobenzoyl chloride, C 6 H 4 C1.COC1, is obtained in the
pure state by the action of phosphorus chloride on the acid. It
is a heavy, powerfully refractive liquid which fumes in the air
and boils at 235 238 (Emmerling).

Orthochlorobenzonitril, C 6 H 4 C1.CN, is formed by the action of
phosphorus pentachloride on salicylamide, C 6 H 4 (OH)CO.NH 2 .
It crystallizes from hot water or ether in white needles, which
smell like benzonitril and melt at 42 43. It sublimes readily,

Beilstein and Reichenbach, Ann. Chem. Pharm. cxxxii. 311.
Hiibner and Upmann, Zeitschr. Chem. 1870, 293.

Hiihner and Biedcrmann, Ann. Chem. Pharm. cxlii. 263 ; Wilkcns and
Ra:k. ibid, ccxxii. 192.

Glutz, ibid, cxliii. 194 ; Ost, Journ. Prakt. Chem. [2] xi. 86
Emmerling, L'cr. Deutsch. Chem. Ges. viii. 880.



METACHLORQBENZOIC ACID. 219

boils at 232, and is converted into orthochlorobenzoic acid when
heated to 150 with dilute hydrochloric acid. 1

2124 Metaclilorobenzoic acid. Herzog, in 1840, found that the
action of chlorine upon benzoic acid produces, among other pro-
ducts, a chlorinated acid resembling benzoic acid, but he did not
analyze the substance. 2 Scharling subsequently obtained an acid
by the distillation of urine with hydrochloric acid, which had the
composition of chlorobenzoic acid, and which he named chloro-
mickmic acid (o/u^a, urine), 3 but, as Gmelin pointed out, it
was not to be distinguished from chlorobenzoic acid. 4 Stenhouse
prepared the latter by treating benzoic or cinnamic acid with
chlorine, bleaching powder or potassium chlorate and hydro-
chloric acid, but was unable to free it from higher chlorine
substitution products. 5 Field, however, found that it can be
obtained pure by boiling benzoic acid with potassium chlorate
and hydrochloric acid, and this was confirmed by Otto. 6 As



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