Organic Syntheses, Coll. Vol. 1, p.125 (1941); Vol. 7, p.12 (1927).
A solution of 50 g. (1.25 moles) of sodium hydroxide
in 1.5 l. of water is prepared in a 5-l. flask
, and the solution is heated to gentle boiling. To the hot solution is added, in small quantities, 330 g. (0.9 mole) of anhydro-2-hydroxymercuri-3-nitrobenzoic acid (p. 56) (Note 1)
. The mixture is stirred after the addition of each portion of about 50 g. until the material has gone into solution except for a small residue. The flask is then fitted with a stirrer and addition tube (Note 2)
and with a connection to a reflux condenser
. The material is heated to boiling and stirred vigorously. There is slowly added, with continuous stirring, 101 g. (85 cc., 0.95 mole) (Note 3) of concentrated hydrochloric acid
(sp. gr. 1.19). Heating is discontinued at this point, and 31.5 g. (30 cc., 0.5 mole) of glacial acetic acid
(sp. gr. 1.05) (Note 3)
is added slowly. A curdy precipitate forms.
A solution of bromine
is prepared by dissolving 103 g. (1 mole) of sodium bromide
and 160 g. (50.2 cc., 1 mole) of bromine
in 150 cc. of water (Note 4)
. The mixture is stirred, and the bromine
solution is added as rapidly as possible through the shaft of the stirrer. The precipitate dissolves. The solution is heated to boiling for five minutes after the last of the bromine
has been added. The solution is then made slightly alkaline by the addition of 20 g. (0.5 mole) of solid sodium hydroxide
and filtered through a fluted filter
. The filtrate is then made acid to Congo red, using about 150 cc. of concentrated hydrochloric acid
. The precipitated 2-bromo-3-nitrobenzoic acid
is filtered with suction and sucked as dry as possible. It is then crystallized from 1 l. of hot 30 per cent alcohol
. The yield of product melting at 185–187°
is 130–150 g.
per cent of the theoretical amount, based on the 3-nitrophthalic acid
used). About 25 g.
of material melting at about 175°
can be recovered from the mother liquor.
The reaction product from the mercuration of 3-nitrophthalic acid
(1 mole) is used. The mercury compound can be used without drying if desired. If this is done, solution takes place much more readily.
A rapid distribution of the added material is necessary to prevent a local excess of the reagent added. This is very important when hydrochloric acid
is added, as this tends to decompose the mercury compound. A convenient arrangement consists of a three-way tube of about 15-mm. bore
. The stirrer operates through the center tube. The other arms are used for the condenser and for the addition of material. A three-necked flask provided with a long-stemmed separatory funnel
reaching below the stirrer may be used.
The addition of one mole of hydrochloric acid
allows the formation of one mole of sodium chloride
, which is of advantage in the subsequent addition of halogen, owing to the formation of a sodium salt of the chloromercuric acid
, this being more soluble and hence more reactive than the anhydro compound. Acetic acid
is used for the final acidification because it does not decompose the mercury compound. The replacement by bromine
takes place best in a slightly acid medium.
can be prepared by the nitration of 2-bromobenzoic acid
, the 2,3 acid being separated from the 2,5 acid, which is the principal product of the nitration, by fractional crystallization of the potassium salts from water.1
This preparation is referenced from:
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