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Organic syntheses - Roger A.

Roger A. Organic syntheses - Chapman, 1936. - 110 p.
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2. Notes
1. The oa-amyl bromide was prepared in the usual manner (Org.
Syn. Coll. Vol. x, 23) and distilled at 127-129.
2. Sometimes a white precipitate begins to form immediately, but
more often it does not appear until after twenty to thirty minutes of
refiuxing. If this period of heating is materially decreased, a sudden
exothermic reaction occurs when the ether is removed and the yield may be
seriously reduced. Longer periods of heating do not increase the yield of
3. Solution takes place slowly and is hastened considerably by
the use of a mechanical stirrer.
4. The aldehyde dissolved by the wash water may be recovered by
steam distillation, but this is scarcely worth while since hexaldehyde is
not very soluble in water.
3. Methods of Preparation
Hexaldehyde has been prepared from caproic acid by passing it over
zinc dust at 300,1 by reaction with amylene at 300 in the presence of
thorium oxide,2 by passing it over manganous oxide at 300-360 with two
volumes of formic acid,3 and by distillation of the calcium salt with
calcium formate.4 It has also been prepared by heating a-hydroxyheptoic
acid or better a-acetoxyheptoic acid,5 and by the reaction of ethyl
orthoformate with e-amylmagnesium bromide.6
1 Maihle, Chem. Ztg. 88, 243 (1909).
2 Maihle, ibid. 34, 1174 (1910).
3 Sabatier and Maihle, Compt. rend. 158, 986 (1914).
4 Lieben and Janecek, Ann. 187,130 (1877).
8 Bagard, Bull. soc. chim. [4] 1, 309 (1907).
6 Bachman, J. Am. Chem. Soc. 55, 428A (1933).
CeH5COCH2CH3 + CHaONO---------> C6H5COCCH3 + NIcII
Submitted by Walter H. Hartung and Frank Crosslev. Checked
by Reynold C. Fuson and R. F. Peterson.
1. Procedure
A 3-I. three-necked, round-bottomed flask (A, Fig. 1) is provided with a
reflux condenser, liquid-sealed mechanical stirrer,
and two gas delivery tubes (Ti and T2) which extend as far as possible
into the flask. Methyl nitrite is generated in a 2-1. Erlenmeyer flask A
which is fitted with a 500-cc. dropping funnel N and connected to A by
the tube Ti. Dry hydrogen chloride (Org. Syn. Coll. Vol. 1, 287) is
introduced through T2. The apparatus is assembled preferably in a hood
with effective draft.
In A is placed a solution of 469 g. (3.5 moles) of propiophenone
(Note i) in 2300 cc. of ordinary ethyl ether and in A a mixture of 290
g. (4.0 moles) of 95 per cent sodium nitrite, 180 cc. (142 g.,
4.5 moles) of methyl alcohol, and 170 cc. of water. In the dropping
funnel N is placed 455 cc. of cold dilute sulfuric acid (prepared by
adding one volume of concentrated acid to two volumes of water).
The stirrer is started, and hydrogen chloride is introduced through
T2 at the rate of 6-10 bubbles a second. The acid in N is allowed to drop
slowly into B, and the gaseous methyl nitrite (Note 2) is introduced
through Ti into the reaction mixture. The solution in A develops a brown-
red color, and after about ten minutes the ether begins to reflux gently
(Note 3). The rate of evolution of methyl nitrite is then adjusted so
that the ether continues to reflux gently. The time required for addition
of the methyl nitrite is about four hours. Stirring and addition of
hydrogen chloride are continued for thirty minutes longer; at the end of
this time the solution has ceased boiling and has assumed a clear yellow
The reaction mixture is allowed to stand for several hours
(preferably overnight) and is then extracted repeatedly with 500-cc.
portions of 10 per cent sodium hydroxide solution, until the alkaline
extracting medium remains practically colorless when shaken with the
ethereal solution (Note 4). Usually five 500-cc. portions of the sodium
hydroxide solution are required. The combined alkaline extracts are
poured slowly, with stirring, into a mixture of 700-750 cc. of
concentrated hydrochloric acid and about 1 kg. of ice. The crystals of
isonitrosopropiophenone are filtered with suction and dried. The product
weighs 370-390 g. (63-66 per cent of the theoretical amount) and melts at
in-1130. This material can be crystallized from toluene (about 550 cc.)
and yields 315-335 g. of snow-white crystals, m.p. 112-113 (Note 5).
2. Notes
1. Propiophenone may be prepared in 70-80 per cent yields from
benzene and propionyl chloride or propionic anhydride, in the presence of
aluminum chloride.
2. For the preparation of small amounts of the isonitroso-ketone
it is more convenient to employ a higher-boiling alkyl nitrite, such as
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