Organic Syntheses, Coll. Vol. 5, p.54 (1973); Vol. 48, p.12 (1968).
when dry detonates violently on being scraped or heated, and it is strongly recommended that it be kept wet with solvent at all times. It should be prepared and used in a hood
behind a safety screen. A wet towel or sponge should be kept within easy reach with which to deactivate any spilled material, which should then be disposed of by flooding with water.
. The solvent-wet benzenediazonium-2-carboxylate
is washed from the funnel into a 400-ml. beaker
with ca. 150 ml. of 1,2-dichloroethane
, dispensed from a plastic wash bottle
, with the aid of a plastic spatula (Note 9)
. The resultant slurry is added during 3–5 minutes to 1250 ml. of gently boiling, stirred 1,2-dichloroethane
in a 2-l. beaker
on a magnetic stirrer-hot plate
in the hood (Note 10)
. Frothing ceases a few minutes after completion of the addition, and the mixture assumes a clear red-brown color, signaling the end of the reaction.
A 1-l., two-necked, round-bottomed flask
is equipped with a 1-l. addition funnel
and a Claisen distillation head
and water-cooled condenser. The cooled reaction mixture is transferred to the funnel, and enough of it is admitted to the flask to half-fill the latter. The 1,2-dichloroethane
, b.p. 83–84°
, is distilled with the use of magnetic stirring to maintain even ebullition; the remainder of the reaction mixture is added from the funnel at a rate such that the flask remains about half-full. When ca.
75 ml. of dark residue remains in the flask, 300 ml. of ethylene glycol
is added. An air condenser
is substituted for the water-cooled condenser, and distillation is recommenced. A forerun, b.p. <150°, is discarded, and the fraction, b.p. 150–197°
, is collected (Note 11)
. The distillate is cooled to 10°, and the product is collected by suction filtration, washed with 10–15 ml. of cold ethylene glycol
and several times with water, and dried at atmospheric, pressure over phosphorus pentoxide
. The yield of biphenylene
, m.p. 109–112°
, is 4.0–5.6 g.
, based on anthranilic acid
). Additional biphenylene
) can be obtained from the mother liquor and ethylene glycol
washings by redistillation or dilution with water (Note 12)
The submitters used practical grade anthranilic acid from Mallinckrodt Chemical Works
The submitters used commercial tetrahydrofuran
. The checkers found that the product yield was the same when either practical grade or Fisher Certified reagent grade tetrahydrofuran
The submitters used "amyl nitrite" U.S.P. from Mallinckrodt Chemical Works
; isoamyl nitrite supplied by Matheson, Coleman and Bell
is apparently the same material. They found that other alkyl nitrites (ethyl, n
-amyl) may be used with equal success. Subsequent to the checking of this procedure, they reported that the amount of nitrite can be reduced to a 20% molar excess.
The product should be used immediately because it deteriorates slowly at room temperature. It is freed of tetrahydrofuran
by washing with the solvent to be used in subsequent reactions and transferred as a slurry in that solvent (cf. procedure B
). Traces of water, if present, do not appear to interfere with subsequent reactions of diazonium carboxylates, as observed in the submitters' laboratory.
The submitters have found that this procedure works equally well with many substituted anthranilic acids; however, it does not work with 3-chloro-, 5-cholro, 4-nitro-, 5-nitro-, and 4,5-benzoanthranilic acids.
Although it strongly recommended that the product not be dried, particularly when prepared on the scale described here, the following slightly modified procedure can be used for the preparation of solvent-free benzenediazonium-2-carboxylate
. A solution of 2.74 g. (0.020 mole) of anthranilic acid
and 0.030 g. of trichloroacetic acid in 30 ml. of tetrahydrofuran
is prepared in a 100-ml. beaker
equipped with a thermometer and cooled in a bath of ca.
25 g. of crushed ice. The solution is stirred magnetically, and 5 ml. (4.4 g., 0.038 mole) of isoamyl nitrite (Note 4)
is added during ca.
0.5 minute. The mixture is stirred and allowed to warm to room temperature over a period of 1 hour. It is cooled to 10°, and the product is collected by suction filtration with the use of a plastic Buchner funnel and plastic spatula and washed with ice-cold tetrahydrofuran
until the washings are colorless. The yield of air-dried (30 minutes) benzenediazonium-2-carboxylate
is 2.55–2.88 g.
). (Caution! Danger of detonation! See above.) (Note 13)
The checkers added the slurry via a large, medium-bore, glass funnel with fire-polished edges
. In one of three runs a small, sharp report was heard, apparently from a source above the liquid in the beaker; the yield of biphenylene
in this run did not differ significantly from that obtained in the other runs.
The checkers found it necessary to heat the condenser with a microburner
from time to time to prevent clogging with biphenylene
. The submitters have reported that this can be avoided by connecting the Claisen head via an adapter
to a two-necked receiving flask
fitted with an upright water-cooled condenser
and cooled by immersion in ice-water.
For convenient preparation and workup of larger amounts of biphenylene
, several runs can be combined after the decomposition of the benzenediazonium-2-carboxylate
. Thus the submitters obtained 19.1 g.
) of air-dried biphenylene
by combining four batches. They found that the use of larger amounts of 1,2-dichloroethane
resulted in a moderate increase in yield; by combining four batches, each prepared in 2. 75 l. of 1,2-dichloroethane
in a 4-l. beaker
, they obtained 22.8 g.
) of product.
The checkers transferred the solvent-moist product to a tared Petri dish
by means of gentle puff of compressed air through the stem of the funnel; solid adhering to the filter paper and funnel was transferred to the dish with the aid of a soft rubber policeman
, which was also used to spread the product over the surface of the dish. The product was then air-dried for 30 minutes in the hood.
has been prepared in low yield by the reaction of 2,2'-dibromobiphenyl
or 2,2'-biphenyliodonium iodide
with cuprous oxide
by the action of cupric chloride
on 2,2'-biphenyl-dimagnesium dibromide
by pyrolysis or photolysis of phthaloyl peroxide
by reaction of o-fluoro-bromobenzene
with lithium amalgam
by reaction of o-bromoiodobenzene
and by the decomposition of diphenyliodonium-2-carboxylate
and by the oxidation of 1-aminobenzotriazole
with lead tetraacetate
4. Merits of the Preparation
These procedures illustrate facile methods for the preparation of benzenediazonium-2-carboxylate
and its derivatives15
and of biphenylene
and certain biphenylene derivatives.13
The latter preparation is far more convenient and proceeds in much better yield than do previous, syntheses, which involve more steps, less accessible intermediates, and more complicated techniques.
This preparation is referenced from:
Chemical Abstracts Nomenclature (Collective Index Number);
Perfluorobutyric or trifluoroacetic acid
hydrochloric acid (7647-01-0)
acetic acid (64-19-7)
silver oxide (20667-12-3)
ethylene glycol (107-21-1)
cupric chloride (7447-39-4)
amyl nitrite (463-04-7)
Anthranilic Acid (118-92-3)
Isoamyl nitrite (110-46-3)
trichloroacetic acid (76-03-9)
phosphorus pentoxide (1314-56-3)
Benzenediazonium, o-carboxy-, hydroxide
lead tetraacetate (546-67-8)
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