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by water :

C 6 H 8 Br 2 (C0 2 H) 2 + H 2 O = C 6 H8Br(OH)(CO 2 H) 2 + HBr.

It is readily soluble in water and crystallizes in small rhombic
prisms or tablets. On heating with baryta water it is converted
into the following compound. 3

Tarlrophthalic acid, C 6 H 8 (OH) 2 (C0 2 H) 2 is best obtained by
dissolving the anhydride of tetrahydrophthalic acid in boiling
water, and adding to one part of the anhydride rather more than
an equal amount of bromine, the mixture being then heated on
the water bath and treated with baryta water until the liquid
has a permanent alkaline reaction. The barium salt is obtained
on concentration in plates, from which the tartrophthalic acid is
prepared by means of sulphuric acid. It crystallizes from a con-
centrated solution in colourless prisms containing two molecules
of water, which are lost in a vacuum. On heating with hydri-
odic acid it is converted into hexhydrophthalic acid, the

1 Baeyer, Ann. Chcm. P/iarm. clxvi. 344.

2 Mierski, Bar. Deutsch. Chcm. Gcs. iv. 558.

3 Baeyer, Ann. Cfwm. Pharm. clxvi. 354.



CHLOROPHTHALIC ACIDS. 471

relation existing between these two bodies being similar to that
between succinic and tartaric acids, while tetrahydrophthalie
acid corresponds to fumaric acid.



HALOGEN SUBSTITUTION PRODUCTS OF
PHTHALIC ACID.

2246 Chlorine does not act upon free phthalic acid, even in
the presence of iodine ; substitution takes place, however, when
the gas is passed into an alkaline solution of the acid. Auerbach
obtained in this way a monoshlorophthalic acid, which crystal-
lized from benzene in needles, melted at 149 150, was readily
soluble in alcohol and remained on the evaporation of this solu-
tion as a syrup which gradually solidified. On heating, it yielded
an anhydride boiling at 140 143 . 1 Kriiger obtained different
results by oxidizing the two chloro-orthotoluic acids with potas-
sium permanganate in faintly alkaline solution. 2

v-Chlorophthalic acid, C 6 H 3 C1(CO 2 H) 2 (3 : 1 : 2), is also formed
by the oxidation of the dichloronaphthalene melting at 107, and
crystallizes from hot water in stellate groups of silky needles,
which melt at 184 and yield an anhydride which sublimes in
long needles and melts at 122 123 . 3

a-Chlorophthalic acid (4:1:2) has also been prepared by the
oxidation of e-dichloronaphthalene 4 and by the action of phos-
phorus pentachloride on the corresponding sulphonic acid. 6 It
is more readily soluble in water and alcohol than the v-acid,
and crystallizes in silky needles, which melt at 130 134
(Kruger) but according to Claus and Re"e at 148. It decom-
poses on distillation into water and the anhydride, which
crystallizes in lustrous, asymmetric tablets, and melts at 96 97.

Dichlorophthalic acid. C 6 H 2 C1 2 (CO 2 H) 2 , is obtained by heating
dichloronaphthalene tetrachloride, C 10 C1. 2 H ? C1 4 , 6 and /9-dichloro-
naphthalene 7 with nitric acid. It is readily soluble in alcohol
and hot water, and crystallizes in compact prisms, which melt at

1 Jahrcsb. Chcm. 1880, 862.

2 JBcr. Deutsch. Chcm. Gcs. xviii. 1758. 3 Onarcschi, ibid. xix. 13

4 Alcn, Bull. S'oc. Chcm. xxxvi. 434 ; Clans and Dchuc, Bcr. Deutsch, Chcm.
Gcs. xv. 319 ; Claus and Miiller, ibid, xviii. 3073.
8 R<5e, ibid, xviii. 3359 ; Inaugurate. Bern. 1886.

6 Faust, Ann. Chcm. Pharm. clx. 64.

7 Attcrberg, Bcr. Deutsch. Chcm. Gcs. x. 574.



472 AROMATIC COMPOUNDS.






183 185. Its anhydride melts at 187 and forms crystals
which are very similar to those of benzoic acid.

Trichlorophthalic acid, C 6 HC1 3 (CO 2 H) 2 , which has beon pre-
pared by the oxidation of /3-pentachloronaphthalene with nitric
acid, forms a yellowish, crystalline mass, and is converted on
heating into the anhydride which melts at 157 and sublimes
in long needles. 1

Tctrachlorophthalic acid, CC1 4 (CO 2 H) 2 . was obtained from
a-pentachloronaphthalene. It is also formed by the action of
chlorine on phthalic acid in presence of antimony chloride,' 2 and
crystallizes from water in small plates or hard, thick prisms,
which melt at 250 and form an anhydride, which crystallizes in
long needles, melting at 245 ; these are insolub!e in cold
water but gradually dissolve in hot water, the acid being re-
formed. 3

Ethyl tetrachlorophthalate, C C1 4 (CO 2 C 2 H 5 ) 2 , is prepared by
heating the silver salt with ethyl iodide ; it forms large prisms
which melt at 60. An isomerig compound is obtained when
the acid is treated with phosphorus chloride and the tetrachloro-
phthalyl chloride formed submitted to the action, of sodium
ethylate (p. 461) ; it crystallizes in tablets and melts at 124 . 4

v-Bromophthalic acid, C 6 H 3 Br(C0 2 H) 2 (3:1: 2), is formed
when phthalic acid is heated with bromine and water to 180;
it is an indistinctly crystalline powder which melts at 138 140
and yields an anhydride melting at 60 65. 5

a-Bromophthalic acid (4:1: 2) is obtained by the oxidation of
bromonitronaphthalene, C 10 H 6 Br(NO 2 ), 6 tetrabromo-yS-naphthol 7
and dibromamidonaphthalene 8 with potassium permanganate.
It crystallizes in white, prismatic needles, which melt at 175
176 and are converted into an anhydride melting at 131 132.

a-Dibromophthalic acid, C 6 H 2 Br 2 (CO 2 H) 2 (3:6:1:2), was pre-
pared by Guareschi by the oxidation of a-dibromonaphthalenc
with nitric acid. It separates from hot water as a crystalline
powder, which melts at about 135 with decomposition; on
further heating the anhydride sublimes in light, nacreous needles
melting at 207'5 208.

1 Atterbcrg and Widman, Ber. Dculsch. Chcm. Ges. x. 1843.

2 Ibid, xviii. Ref. 676. 3 Griibe, Ann. Chcm. Pkarm. cxlix. 18.

4 Griibc, Bcr. Dcutsch. Chcm. Gcs. xvi. 860.

5 Faust, Ann. Cliem. Pharm. clx. C2 ; Peclimann, Bcr. Deutscli. Chcm. Gcs. xii
2126.

6 Guareschi, Ann. Chem. Phcmn. ccxxii. 262.

7 A. J. Smith, Journ. Chcm. Soc. 1879, i. 792.

8 Meldola, ibid. 1885, i. 511 ; see also Stallard, ibid-. 1886, i. 187.



NITROPIITHALIC ACIDS. 473

0-Dibromophthalic acid is formed by the oxidation of penta-
bromo-a-naphthol, and crystallizes from hot water in reedles
which melt at 200 and are thus converted into the anhydride,
which sublimes in long needles and melts at 208. The salts of
this acid are, with the exception of those of the alkali metals,
only slightly soluble in water. 1

Tribromophthalic acid, C,.HBr 3 (CO 2 H) 2 , is prepared from penta-
bromo-/3-naphthol ; it is almost insoluble in cold water and
crystallizes from hot water in lustrous plates which melt at
190 191 and are converted at a higher temperature into the
anhydride, which sublimes in white plates and melts at 157. 2

Tctrabromophthalic acid, C 6 Br 4 (CO 2 H) 2 , was obtained by Bliim-
lein as a product of the oxidation of tetrabromorthoxylene ; it is
almost insoluble in the ordinary solvents, and crystallizes from
boiling water in lustrous needles, and on the evaporation of its
solution in benzene in prisms, which melt at 266 and are thus
converted into the anhydride, which sublimes in small, lustrous
needles, melting at 258 259. Its salts are for the most part
insoluble, or only slightly soluble, in water.



NITROPHTHALIC ACIDS.

2247 v-Nitrophthalic acid, C 6 H 3 (NO 2 )(CO 2 H) 2 (3:2:1), is
formed by the continued boiling of naphthalene with nitric acid, 3
by the action of a mixture of nitric and sulphuric acids on phthalic
acid 4 and by the oxidation a-nitronaphthalene with potassium
permanganate 5 or of a-dinitronaphthalene with nitric acid. 6 In
order to prepare it, one part of nitronaphthalene is dissolved in
7 parts of 90 per cent, acetic acid, and to this are gradually added
5 parts of chromium trioxide ; water is then added and the solu-
tion extracted with chloroform to remove the orthonitrophthalide
which is always formed. The acid liquid is then treated with
barium carbonate, and the insoluble barium nitrophthalate de-
composed by carbonate of soda. The solution of the sodium
salt is then acidified and the nitrophthalic acid extracted with

TMiimlcin, Her. Dcutsch. Chem.Gcs. xvii. 2485.

Flessa, ibid. xvii. 1479.

Laurent, Ann. Chcm. Phnnn. xli. 110 ; Marignar, ibid. xlii. 7.

Faust, -ibid. clx. 57.

Ouureschi, Her. Dcutftch. Chcm. Gen. x. 294.

Aguiar, ibid. v. 899.



474 AROMATIC COMPOUNDS.

ether. 1 It crystallizes from this in light yellow, monoclinic
prisms, which are slightly soluble in cold, more freely in hot
water, and readily in alcohol. It decomposes on heating into
water and the anhydride ; in a small sealed tube it melts at 218
(Miller).

Acid ethyl v-nitrophthalate, C 6 H 3 (NO 2 )(CO 2 C 2 H 5 )C0 2 H, is ob-
tained by passing hydrochloric acid into an alcoholic solution of
the acid ; it crystallizes from hot water in long needles, melting
at 110-5.

Normal ethyl v-nitrophthalate, C 6 H 3 (N0 2 )(CO 2 C 2 H 5 ). 2 , is pre-
pared from the silver salt by the action of ethyl iodide, and
crystallizes from alcohol in long, rhombic prisms, melting at 45
(Miller).

a-Nitrophthalic acid, C 6 H 3 (NO 2 )(CO 2 H) 2 +H 2 O (4:2:1), is
formed, together with the preceding compound, by the nitration
of phthalic acid. 2 In order to prepare it, 50 grms. of phthalic
acid are heated with 75 grms of sulphuric acid and the same
amount of fuming nitric acid for two hours on the water bath ;
120 grins, of water are then added, and the whole allowed to
stand for twelve hours in the cold. The precipitate is washed
and extracted with ether, the residue after the evaporation of
this consisting of a mixture of the two acids accompanied by a
little picric acid. It is re-crystallized from water, to remove the
greater portion of the v-acid, the mother liquor evaporated to
dryness, and the residue dissolved in alcohol and treated with
hydrochloric acid gas, which converts the v-acid into the acid and
the a-acid into the normal ether. These are separated by car-
bonate of soda solution, and the normal ether then converted
into the potassium salt by the action of alcoholic potash ; this
is then acidified with hydrochloric acid and the free acid ex-
tracted with ether. It may be still more easily obtained by
heating paranitrophthalide with dilute nitric acid to 140 . 3 It
crystallizes in small needles, which are readily soluble in water
and alcohol, effloresce in the air, lose their water at 100, and
then melt at 161.

Acid ethyl a-nitrophthalate, C 6 H 3 (NO 2 )(CO 2 .C 2 H 6 )CO 2 H, is
formed in small quantity when an alcoholic solution of the acid
is treated for a short time with hydrochloric acid, and crystallizes
from water, in long, thin needles, which melt at 127 128.

1 Beilstein and Ktirbatow, Ann. Chcm. PJiarm. ccii. 217.

2 Miller, ibid, ccviii. 223.

3 Honig, Bcr. Dcutsch. Chcm. Gcs. xvii. 3447.



AMIDOPHTHALIC ACIDS. 475

Normal ethyl a-nitrophthalate, C 6 H 3 (NO 2 )(CO 2 .C 2 H 5 ) 2 , is in-
soluble in water and crystallizes from alcohol in lustrous tablets,
which melt at 34.

a-NitropUhalic anhydride, C 8 H 3 (NO 2 )O 3 , is obtained by heat-
ing the acid to 170 and subliming the residue in a current of
air at 210, in the form of fascicular crystals, which melt at 114
and are readily soluble in ether and hot water. If the aqueous
solution be evaporated, a-nitrophthalic acid is deposited.

Dinitrophthalic acid, CgH^NO^CCOgH^ (5:3:2:1), is
formed when /3-dinitronaphphthalene is heated to 150 with
nitric acid of sp. gr. I'lo in a sealed tube, small quantities of
nitro-phthalic acid, s-dinitrobenzoic acid, and picric acid being
also formed. It crystallizes in large prisms, which are readily
soluble in water and alcohol, and melt at 226 . 1



/C0 2 H

AMIDOPHTHALIC ACIDS, C 6 H / NH 2 .

\C0 2 H

2248 v-Amidcphthalic acid. When the v-nitro-acid is treated
with tin and hydrochloric acid in the cold, needles of the com-
pound C G H 3 (NH 2 ClH)(C0 2 H) 2 + SnCl 2 +2H 2 are formed. If
the hydrochloric acid solution of this be treated with sulphuretted
hydrogen and evaporated, carbon dioxide is given off and meta-
amidobenzoic acid formed.

Ethyl v-amidophthalate, C 6 H 3 (NH 2 )(CO 2 .C 2 H 5 ) 2 , is prepared
by treating a well-cooled alcoholic solution of the ether of the
nitro-acid with hydrochloric acid and zinc dust. It is a yellow
liquid, which decomposes on heating and forms a splendid blue,
fluorescent solution in ether (Miller).

a-Amidophthalic acid. When the a-nitro-acid is reduced, no
carbon dioxide is evolved, but no double tin salt is formed. On
removing the tin and evaporating, however, carbon dioxide is
evolved just as in the case of the v-acid, and metamidobenzoic
acid formed.

If the reduction be carried on by means of zinc dust and
acetic acid, a double compound of zinc acetate and zinc amido-
phenate is formed, which has probably the constitution C H 3
(NH 2 )(CO 2 H)CO i .Zn.O.CO.CH 3 , and crystallizes in fine, whit,

1 Boilstein and Kurbatow^ww. Chcm. Phftrm. ccii. 224.



476 AROMATIC COMPOUNDS.

needles, which form an almost colourless solution in hot water,
while its solution in acetic acid is coloured yelbw and has a
green fluorescence. It dissolves in caustic soda, but the solution
decomposes on heating, zinc carbonate is deposited and the
amidophthalic acid decomposed. 1

Ethyl a-amidophthalate was first prepared by Baeyer but
mistaken for the v-compound 2 until Miller showed that it is
derived from the a-acid. 3 This substance is obtained in a similar
manner to the isomeric compound ; it is insoluble in water,
slightly soluble in dilute acid, readily in alcohol, from which it
crystallizes in monoclinic prisms, which melt at 95 ; the dilute
ethereal solution shows a faint blue fluorescence.



/CO,H
SULPHOPHTHALIC ACIDS CLH/-SO,H.

\C0 2 H

2249 a-Sulphophthalic acid (1:4:2) is obtained by heating
phthalic acid or phthalic anhydride with strong, fuming sul-
phuric acid, 4 and by the oxidation of /3-naphthalenesulphamide,
C 10 H 7 S0 2 .NH 2 , and dinitronaphtholsulphonic acid, C ]0 H 4 (NO ? ) 2
(OH)SO 3 H. 5 It remains as a syrup when its solution is
evaporated on the water bath, but solidifies after heating for
some time to a mass consisting of stellate groups of sharply
pointed prisms ; these contain a molecule of water, which is lost
at 140, a brownish syrup being formed, which often solidifies
on standing. On heating to 180, the anhydride, C 6 H 3 (C 2 3 )
SO 3 H, is formed as a hard, brown, very hygroscopic mass.

The normal barium salt crystallizes in plates or silky needles,
slightly soluble in water ; when it is dissolved in the necessary
amount of hydrochloric acid, the monacid salt, C G H 3 (CO 2 BaSO s )
CO 2 H+2H 2 O, is formed, and crystallizes from hot water in large
needles ; it is converted by solution in an excess of hydrochloric
acid into the diacid salt, (C 6 H 3 (CO 2 H) 2 SO 3 ) 2 Ba + 5II 2 O, which
also crystallizes in lustrous needles.

1 Bernthsen and Semper, Ber. Dcutsch. Chem. Ges. xix. 164.

2 Ibid. x. 124 and 1079.

3 Ibid, xi 1191.

4 Low, Ann. Ohcm. Pharm. cxliii. 249 ; Rce, Bcr, Dcutsch. Cficm. Ges. xviii.
1629 ; Inaugurahi. Bern. 1886 ; Ann. Ctwm. Pharm. ccxxxiii. 216.

5 Grabo, Bcr. Dcutsch. Chcm. Ges. xviii. 1126.



SULPHAMICPHTHALIO ACIDS. 477

When the monacid ammonium salt is heated, the ammonium
salt of a-sulphophthalimide is formed ; it crystallizes in mono-
symmetric prisms, and is decomposed on heating with formation
of phthalimide :

/ >b /C=NH

^6^3 CO = C 6 H 4 < >0 + S0 2 + NH 2 4 H 0.

X S0 3 NH 4 \CO

a-Sulphamidophthalic acid, C 6 H 3 (SO 3 .NH 2 )(CO 2 H) 2 . When
a-sulphophthalic anhydride is treated with phosphorus penta-
chloride, the monochloride, C ( .H 3 (SO 2 C1)(CO 2 H) 2 , is formed, and
is converted by ammonia into the amide, which crystallizes
from water in small, transparent prisms (Ree).

v-Sulphophthalic acid (1 : 3 : 2) is formed when a-naphthalene-
sulphamide is oxidized with potassium permanganate. The first
product is the anhydride of sulphamidophthalic acid, which
yields the sulphonic acid on heating with hydrochloric acid :

/ C0 >NH /C0 2 H

C C H 3 SO 9 4~ 2H 2 O = CgH 4 ~ SO 3 H -f-NH 3 .

\C0 2 H \C0 2 H

It is readily soluble in water, and forms salts which crystallize
well. 1 The normal barium salt, (C 6 H 3 (CO2) 2 Ba.SO 3 ) 2 Ba+8H 2 O,
crystallizes in transparent tablets.

Sulphamidophthalic anhydride or Sulphinidephthalic acid,
C 8 H 5 NS0 3 + 2H 2 O, crystallizes from hot water in needles, whicli
become anhydrous at 155. Alkalis do not convert it into sul-
phamicphthalic acid ; it is a dibasic acid, the hydrogen of the
imide-group being easily replaced by metals.

Normal potassium sulphinidephthalate, C 8 H 3 K 2 NSO 3 , is very
readily soluble in water and dries to an elastic mass, from whicli
semi-crystalline, spherical masses separate on standing..

Acid potassium sulphinidephthalate, C 8 H 4 KNS0 3 + H 2 O, is
only slightly soluble in cold, readily in hot water, and crystallizes
in long acute prisms, which rapidly lose their water at 100.

Normal silver sulphimdephthalafe, C 8 H 3 Ag 2 NSO 3 4- H 2 O, is a
white precipitate, which is scarcely soluble in boiling water, but
dissolves in a hot solution of potassium nitrate and separates out
again on cooling.

1 Remsen and Comstock, Ainer. Chem. Journ. v. 106 ; Stokes, ibid. vi. 262.



478 AROMATIC COMPOUNDS.

Acid silver sulphinidepkthalale, C 8 H 4 AgNSO 3 -f- H 2 0, is
formed when the normal salt is heated with nitric acid, or when
silver nitrate is added to a dilute boiling solution of the acid
potassium salt. It crystallizes on cooling in long, pliant needles,
which become anhydrous below 135.

The silver salt is converted into the methyl ether by treat-
ment with methyl iodide.

Normal methyl sulphinidcphthalate, C 8 H 3 (CH 3 ) 2 NS0 3 , crys-
tallizes from alcohol in colourless needles, which melt at 180 and
readily sublime in iridescent plates.

Acid methyl sulphinidephthalate, C 8 H 4 (CH 3 )NS0 3 , separates
from an alcoholic or hot aqueous solution in long, striated prisms,
or long, narrow tablets, which melt at 190'7 191'7 and readily
volatilize. When it is successively treated with phosphorus
trichloride and methyl alcohol the dimethyl ether is formed.

In order to determine the constitution of the acid sulphinide-
phthalates, the acid potassium salt was heated with phosphorus
pentachloride, the compound C 8 H 3 C1 3 S0 2 NPOC1 2 being formed ;
it crystallizes in small prisms, and is converted by methyl alcohol
into the trimethyl ether, C 8 H 4 (CH 3 ) 3 NS0 6 , which separates from
hot water in needles or long narrow prisms, which melt at 140'5
141'5. The constitution of these compounds is expressed by the
following formulae :

/ Qo l2 > N - POG1 2 r H /, ( ? CH3)2 >NH

o3r~ feU 2 . ^ 6 -H- 3 bo 2 -

\COC1 \CO.OCH 3

Since the monomethyl ether is converted into the diethyl ether
by the action of phosphorus chloride for a short time, followed by
the treatment described above, it follows that in the first of these,
and therefore in the acid sulphinidephthalates, it is the hydrogen
of the imido-group which is replaced (Stokes) :



639 PC1 5 =

\CO:OH

C 6 H 3 ^S0 9 >NCH3 +HC1 + POCL
\COC1



39 . 3632 +HCL

\COC1 \COOCH q



ISOPHTHALIC ACID. 479



ISOPHTHALIC ACID OR METAPHTHALIC ACID.

2250 This compound is formed by the oxidation of meta-
xylene, 1 metatoluic acid, 2 and other meta-compounds with two
side-chains containing carbon. It has also been obtained by
fusing potassium metasulphobenzoate 3 and potassium meta-
bromobenzoate 4 with sodium formate (Part III. p. 35), and has
been found among the products of the oxidation of colophony
with nitric acid. 5 In order to prepare it, metaxylene is converted
into metaxylylene diethyl ether, and this is then oxidized with
chromic acid solution, the reaction proceeding very smoothly. 6
It dissolves in 7,800 parts of water at 25 and in 460 parts at
100, crystallizing in hair-like needles, which usually extend
through the whole liquid, and are readily soluble in alcohol. 7 It
melts at above 300 and sublimes without decomposition.

Potassium isophthalate, C 8 H 4 O 4 K 2 , is readily soluble in water,
less readily in alcohol, from which it crystallizes in fascicular
groups of needles.

Calcium isophthalate, 2C 8 H 4 O 4 Ca + 5H 2 0, is scarcely more
soluble in hot than in cold water and forms fine needles.

Barium isophthalate, 2C 8 H 4 O 4 Ba + 7H 2 0, is readily soluble in
water and crystallizes from a concentrated solution in lustrous
needles, which effloresce in the air. 8

Silver isophthalate, C 8 H 4 O 4 Ag 2 , is an amorphous precipitate,
which, like mercury thiocyanate, forms a voluminous vermiform
mass on heating.

Methyl isophthalate, C 8 H 4 (C0 2 .CH 3 ) 2 , has been prepared from
the silver salt by means of methyl iodide. It crystallizes from
dilute alcohol in long fine needles, melts at 64 65, and distils
without decomposition. 9

Ethyl isophthalate, C 6 H 4 (CO 2 .C 2 H 6 ) 2 , has been obtained by the
action of hydrochloric acid on an alcoholic solution of the acid.

Fittig and Yelguth, Ann. Chcm. Pharm. cxlviii. 11.
Weith and Landolt, Ber. Deutsch. Chcm. Ges. viii. 721.
V. Meyer, Ann. Chcm. Pharm. clvi. 275.
Ador and Meyer, ibid. clix. 16.
Fittig and Storss, ibid, cliii. 284.
W. H. Perkin, jun. Private comtnuniration.
Fittig and Storss, Ann. Chcm. Pharm. cliii. 284.
Kelbe, ibid. ccx. 20.

V. Meyer, Ber. Deutsch. Chcm. Ges. iv. 262 ; Baeyer, Ann. Chcm. 1 harm.
clxvi. 340.



AROMATIC COMPOUNDS.



It is a liquid which possesses a faint but pleasant odour, boils at
about 285, and solidifies at to a dazzling white, radiating mass
(Fittig and Storss).

Phenyl isophihalate, C 6 H 4 (C0 2 .C C H 5 ) 2 , is formed when phenol
is heated with the chloride ; it crystallizes in long, fine needles
which melt at 120 and are only slightly soluble in alcohol. 1

Isophthahjl chloride, C 6 H 4 (COC1) 2 , is obtained by the distilla-
tion of the acid with phosphorus chloride as an oily liquid, which
boils at 276 and solidifies to a radiating, crystalline mass, melting
at 41 (Schreder).

Isophthalamide, C 6 H 4 (CO.NH 2 ) 2 , is formed by the action of
ammonia on the chloride and is a light, white powder, which
melts at 265, is slightly soluble in alcohol, but scarcely dissolves
in any other of the ordinary solvents. On heating with
phosphorus pentoxide it is converted into isophthalonitril. 2

Metacyanolenzoic acid, C 6 H 4 (CN)C0 2 H, is obtained by allow-
ing a hydrochloric acid solution of metadiazobenzoic acid to run
into a solution of copper sulphate and cuprous cyanide :

/N=zNCl /ON

2C 6 H / + Cu 2 (CN) 2 = 2C 6 H 4 < + Cu 2 Cl, + 2N 2 .

X C0 2 H \C0 2 H

It is readily soluble in alcohol and hot water, and crystallizes
from the latter in microscopic, arborescent needles, which after
drying form a dull white powder and melt at 217.

Boiling caustic soda solution readily converts it into iso-
phthalic acid. 3

Ethyl metacyanobenzcate, C 6 H 4 (CN)CO 2 C 2 H 6 , crystallizes in
fine, matted needles, which melt at 48.

Henzenylamidoximemctacarboxylic acid, is prepared by heating
metacyanobenzoic acid for a long time with an alcoholic solution
of hydroxylamine, and forms crystals which are readily soluble
in alcohol and hot water, and melt at 200. It is formed
according to the equation :

/NH 2

/GN rj/

C 6 H 4 < +H 2 N.OH = C 6 H 4 < ^N.OH.



1 Schreder, Ber. Dcutsch. Chem. Gcs. vii. 708.

2 Beyer, Journ. Prakt. C'hcm. [2] xxii. 351.

3 Sandmeyer, Ber. Deutsch. Chem. Gcs. xviii. 1496.



CHLOKO-ISOPHTHALIC ACID. 481

The ethyl ether is prepared in a similar manner from the
corresponding ether of metacyanobenzoic acid and crystallizes
from, hot water in needles, which melt at 118 . 1

Isopkthalonitril, C 6 H 4 (CN) 2 , is formed by the distillation of
potassium benzenemetadisulphonate with potassium cyanide, 2
or of potassium metabromosulphonate with dehydrated potassium
ferrocyanide ; 3 it forms fine needles, which melt at 160 161,
are only very slightly soluble in water, somewhat more readily
in alcohol, and are converted into isophthalic acid by heating
with alkalis.



ADDITION PRODUCTS OF ISOPHTHALIC
ACID.

Tetrahydro-isophthalic acid, C 6 H 8 (C0 2 H) 2 , is prepared by boil-
ing an alkaline solution of isophthalic acid with sodium amalgam
for some time, and crystallizes from hot water in needles, which
melt at 199. Its dimethyl ether is an oily liquid. 4



SUBSTITUTION PRODUCTS OF ISOPHTHALIC
ACID.

2251 Ckloro-isophthalic acid, 2C H 3 C1(C0 2 H) 2 + H 2 O, has
been obtained from the amido-acid by means of the diazo-
reaction, and crystallizes from hot water in long, very fine
needles, which become anhydrous at 120, and melt at 278
(Beyer).



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