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Organic syntheses - Roger A.

Roger A. Organic syntheses - Chapman, 1936. - 110 p.
Download (direct link): organicsintencis1936.pdf
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water. In a porcelain dish the pumice is mixed with a solution of 40 g.
of thorium nitrate crystals [Th (NDsJ i + i 2H0O] in 100 cc. of water and
is evaporated to dryness, with frequent stirring to insure uniform
deposition of the salt. The impregnated pumice is ignited over a Bunsen
burner until decomposition of the nitrate is complete. The pumice carries
about 15 g. of thorium oxide.
2. From the alkaline solution about 10-15 Per cent of the
phenylacetic acid may be recovered by acidification with sulfuric acid.
The acid separates as an oil which crystallizes slowly on cooling.
3. Salt may be added to facilitate the separation.
4. When several runs are made, the residues may be combined and
distilled under reduced pressure. The fraction boiling at 190-2 io°/2o
mm. amounts to about 19 g. per run and is chiefly dibenzyl ketone.
5. Further purification of the product may be effected by
converting the ketone into the bisulfite compound, washing this with
ether, decomposing with sodium bicarbonate, and steam-distilling.
6. When several runs are to be made, the catalyst should be
regenerated after each run by passing air through the reaction tube for
about three hours while the temperature is raised gradually to 550°. The
yield in the first run may be low, especially if all the oxides of
nitrogen have not been removed from the reaction tube.
7. Using the same procedure the following ketones may be obtained
in similar yields: ethyl benzyl ketone from phenylacetic acid and
propionic acid, methyl /C-phenylethyl ketone from hydrocinnamic acid and
acetic acid, and ethyl /3-phenylethyl ketone from hydrocinnamic acid and
propionic acid.
3. Methods of Preparation
Methyl benzyl ketone has been prepared by distilling a mixture of
the barium1 or calcium2 salts of phenylacetic and acetic acids, and by
passing the vapors of these acids over a heated thorium oxide catalyst.
3>4 It has been prepared by the reaction of phenylacetyl chloride with
zinc methyl,5 by rearrangement of "-phenyl /3-methyl ethylene oxide,6 by
heating a-phenyl /3-methyl ethylene glycol with dilute sulfuric acid,7 by
heating the addition product of chloroacetone and phenylmagnesium
bromide,' and by the hydrolysis of a-phenylacetoacetic ester 8 or of
phpnacyl-malonic ester.9 The procedure given here is based upon that of
Senderens 3 and of Pickard and Kenyon.4 It has been reported recently
that " thoria aerogel " is superior to other forms of thoria catalysts
for the preparation of ketones from aliphatic acids or esters.10
1 Radziszewski, Ber. 3, 198 (1870).
2 Young, J. Chem. Soc. 59, 621 (1891).
! Senderens, Ann. cbim. [8] 28, 318 (igij).
4 Pickard and Kenyon, J. Chem. Soc. 105, 1124 (1914).
s Popow, Ber. 5, 500 (1872).
6 Fourneau and Tifieneau, Compt. rend. 141, 663 (1905).
7 Tiffeneau, Ann. chim. [8] 10, 345, 368 (1907).
8 Beckh, Ber. 31, 3163 (1898).
s Metzner, Ann. 298, 378 (1897).
10 Swann, Appel, and Kistler, Ind. Eng. Chem. 26, 388, 1014 (1934)-
2CeHsCH0 + N2H4-H2S04^l CeHsCH=N-N=CHC6H5
C6H5CH=N-N=CHC6HS + (CH3)2S04 + 3H2O
----> 2C6HsCHO + CH3NHNH2-H2S04 + CH3OH
Submitted by H. H. Hait.
Checked by W. W. Hartman and W. D. Peterson.
1. Procedure
(A) Benzalazine.-In a 5-I. round-bottomed flask, provided with a
stout glass mechanical stirrer, are placed 240 g. (1.85 moles) of
powdered hydrazine sulfate (Org. Syn. Coll. Vol. 1, 302), 1800 cc. of
water, and 230 cc. (207 g., 3.4 moles) of 28 per cent aqueous ammonia
(sp. gr. 0.90). The mixture is stirred, and, when the hydrazine sulfate
has dissolved, 440 cc. (460 g., 4.35 moles) of benzaldehyde (Note 1) is
added from a separatory funnel during the course of four to five hours
(Note 2). After the mixture has been stirred for a further two hours, the
precipitated benzalazine is filtered with suction, washed with water, and
pressed thoroughly on a Buchner funnel. The product is dissolved in 800
cc. of boiling 95 per cent ethyl alcohol, and on cooling the azine
separates in yellow needles melting at 92-93°. The yield is 350-360 g.
(91-94 per cent of the theoretical amount); an additional 10-15 g- of
less pure material can be isolated from the mother liquors. The azine is
freed of ethyl alcohol by drying in a vacuum desiccator over calcium
(B) Methylhydr azine Sulfate.-Two hundred grams (0.96 mole) of
benzalazine, 350 cc. of dry, thiophene-free benzene, and 100 cc. (133 g.,
1.05 moles) of dimethyl sulfate (Note 3) are mixed in a 3-I. round-
bottomed flask, provided with a reflux condenser
bearing a calcium chloride tube. The mixture is heated continuously, with
occasional shaking, on a water bath to gentle reflux-ing for five hours.
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