Organic Syntheses, Coll. Vol. 4, p.271 (1963); Vol. 32, p.46 (1952).
Caution! This procedure should be carried out in a good hood, and a spark-proof motor should be used.
A 1-l. three-necked flask
having ground-glass joints is fitted with an efficient reflux condenser
, a dropping funnel
, and a mercury-sealed stirrer
, and all exits are protected by drying tubes (Note 1)
. In the flask are placed 300 ml. of rigorously dried ether (Note 2)
and 13.6 g. (0.36 mole) of pulverized lithium aluminum hydride (Note 3)
. After the mixture has been stirred for 15 minutes, a milky suspension is produced. A solution of 88.6 g. (0.60 mole) of dichloroacetyl chloride
in 75 ml. of dry ether
is added from the dropping funnel (Note 4)
at a rate such as to produce gentle reflux. The process is completed in about 2.5 hours (Note 5)
Agitation is continued for 30 minutes after all the chloride has been introduced, and the excess hydride is then destroyed by the careful, dropwise addition of water to the stirred and cooled reaction mixture. The hydrolysis is accompanied by the formation of a white curdy mass of aluminum hydroxide
, and the mixture has a semisolid consistency when the hydride has been completely decomposed (Note 6)
. With constant stirring, 500 ml. of 10% sulfuric acid
is then added slowly to the mass. Stirring is continued for 30 minutes, and the solution becomes clear during this period.
layer is separated, and the solvent is removed by distillation under atmospheric pressure, and the dark-colored residue is fractionated under reduced pressure through a 25-cm. column packed with glass helices
. The fraction boiling at 37–38.5°/6 mm.
is collected; it weighs 44–45 g.
1.404 (Note 7)
To prevent partial hydrolysis of the lithium aluminum hydride
, the checkers found it desirable to dry the glassware by flaming while dry nitrogen
was being swept through the apparatus.
is recommended since a solvent containing moisture will react to coat the hydride with oxides which will retard its rate of solution. The checkers used ether
dried over sodium wire
The hydride can be pulverized rapidly and safely by breaking the large pieces with a spatula
, followed by careful crushing with a mortar and pestle
The acid chloride was obtained from the Eastman Kodak Company
and was used without prior treatment. The submitters report2
that dichloroacetyl acid
or ethyl dichloroacetate
may be substituted for dichloroacetyl chloride
but that the reaction appears to be smoother with the acid chloride.
The acid chloride should be added slowly since the reaction appears to have a short induction period and it is undesirable to accumulate a large quantity of unreacted material.
The decomposition of the hydride is accompanied by the vigorous evolution of hydrogen
. Cessation of hydrogen
formation is evidence that the hydride is completely decomposed.
The following constants have been reported in the literature for 2,2-dichloroethanol
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