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Synthesis of Carboxylic Acids with 1 1-Dichloroethylene.

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formamide complex [2], a mixture of 4-dimethylaminobenzaldehyde (2) and 4-dimethyIaminoisophthaldialdehyde
(3) is formed from which (3) may be isolated with 15-20 %
yield. 3,5-Dimethyl-N,N-dimethylaniline(4) is even more
easily diformylated. Under conditions which convert ( I )
exclusively to (2) [3] a mixture of about equal parts of
unchanged (4), 4-dimethylamino-2,6-dimethylbenzaldehyde
(S), and 4-dimethylamino-2,6-dimethylisophthaldialdehyde
(6) is formed. The application of more than two moles of
formylating agent results in the exclusive formation of the
dialdehyde (6) in 60-80% yield. Monoformylation of (4)
can only be achieved by adding one mole of the POC13-DMF
complex at 5 "C very slowly to a large excess (5- 10 moles)
of the amine.
[ I ] The only exception - although with a pseudp-aromatic
system - seems to be the preparation of azulene-l,3-dialdehyde
from azulene; K . Hafner and C. Bernhard, Angew. Chem. 69,
533 (1957); Liebigs Ann. Chem. 625, 108 (1959).
[21 In principle, these syntheses can be carried out as well with
N-formyl-N-methylaniline;however, the separation of the basic
aldehydes from the N-methylaniline is more difficult.
[3] Org. Syntheses, COIL Vol. IV, 331 (1963).
[4]Analogously (6), m.p. 79 "C, is obtained in 81 :/o yield.
Steam distillation of the crude product is unnecessary in this case.
Synthesis of Carboxylic Acids with
By Dr. K. Bott
Forschungslaboratorien der Chemische Werke Huls AG.,
Marl (Germany)
The constitution of the aldehydes (3), (5), and (6) was
ascertained by NMR-spectroscopy : (5) displays, beside
signals for the C-methyl (T = 7.45) and N-methyl (T = 7.00)
groups, only one signal for the two aromatic protons (T =
3.70) and one signal (unsplit) for the aldehydic proton (T =
-0.08). The dialdehydes (3) and (6) each give two signals
for aldehydic protons (T = 0.03 and -0.20, resp. 7 = 0.10 and
-0.28); (6) gives furthermore a split signal for the C-methyl
groups (T = 7.40 and 7.20). N o indication was obtained for
the presence of the 2-dimethylaminoisophthaldialdehydesisomeric with (3) and (6). The introduction of a third formyl
group was not possible even under more rigid conditions.
4-DimethylaminoisopAthaldialdehyde(3) [4]:
N-Dimethylaniline (12.1 g) is added to phosphorus oxychloride (50.0 g) and D M F (81.2 g). The reaction mixture
is heated with stirring and exclusion of moisture for 16 hours
to 60-65 "C, then poured o n ice (600 g), and 33 % NaOH
(150 ml) is added at no more than 15 '. After several hours'
cooling to 0 "C, the crystalline precipitate, consisting of (2)
and (3), is filtered off, washed with water and dried in
vacuum (11.3 g). Exhaustive ether extraction of the alkaline
mother liquor followed by evaporation of the ether yields
further 3.5 g. To separate (3) from (2) the product is distilled
with steam until the distillate does not deposit any more
crystals of (2) on cooling to 0 "C. The crude dialdehyde (3)
(3.4 g) separates in crystalline form from the aqueous solution
(100 ml) remaining in the distillation flask o n cooling to
0 OC. After two recrystallizations from ligroine yellowish
felted needles of pure (3), m. p. 72 'C, are obtained. Yield:
2.4 g (14%).
Treatment of carbinols, carbinol esters, or olefins obtainable from carbinois by loss of water with I,l-dichloroethylene in 80 to 100% sulfuric acid leads to substituted
propionic acids (3) (cf. Table). The reaction, which takes
place at 0 to 15 "C, is greatly accelerated by boron trifluoride
and gives particularly good yields when carbonium ions can
easily be formed from the carbinols or olefins used.
Carbinol, ester, or olefin
Product ( 3 )
1 -8romoadamantane
a-Methyl benzyl alcohol
exo-Norbornylacetic acid
I-Adamantanylacetic acid [ I ]
1-Adamantanylacetic acid
3-Phenylbutyric acid;
carboxylic acids of higher
molecular weight [a]
3,3-Diphenylpropionic acid
3,3-Dimethylbutyric acid [bl
3,3-Dimethylbutyric acid
3,3-Dimethylbutyric acid
t-Butyl chloride
t-Butyl alcohol
of 13)
[a] These acids (structure not yet clarified) are probably formed by
oligomerization of styrene.
[b] Diisobutene (dimerisation product of isobutene, principally 2,4,4trimethyl-I- and -2-pentene) and isobutyl alcohol yield only 3,3-dimethylbutyric acid.
The principle of this carboxylic acid synthesis consists in
addition of a carbonium ion ( I ) to 1,l-dichloroethylene,
giving (2), followcd by hydrolysis to the acid (3).
4-DirnethyIamino-2,6-dimethylbenzaldehyde (5) :
A formylating mixture prepared from phosphorus oxychloride (15.6 g) and dimethylformamide (30.0 g) is added
dropwise, with stirring and exclusion of moisture, within
4 hours at 5-10 "C to 3,5-dimethyl-N,N-dimethylaniline
(75.5 g). After keeping the reaction mixture for 16 hours at
25-3OoC, it is decomposed with ice (300 g), made alkaline
with 33 % NaOH (75 ml) and extracted with ether. After
evaporation of the ether, excess amine (4) is distilled off
(56.6 g; b.p. 61-62'C/0.2 mm), and (5) is obtained in thick,
almost colorless plates (12.5 g, 69 %) from the residue after
one recrystallization from ligroine, m.p. 83 "C.
Received: September 15th. 1965 [Z 60/885 IE]
German version: Angew. Chem. 77, 967 (1965)
[*I This work was supported by Public Health Service Research
Grant CA 07272-02 of the National Cancer Institute, Bethesda,
Md. (U.S.A.).
Received: September 15th, 1965 [Z 61/887 IE]
German version: Angew. Chem. 77, 967 (1965)
[ I ] H . Stetter, M . Schwarz, and A. Hirschhorn, Chem. Ber. 92,
1630 (1959).
Formation of Carbonyl Compounds from Azines or
Hydrazones with Active Manganese Dioxide
By Priv.-Doz. Dr. G . Maier and cand. chem. U. Heep
Institut fur Organische Chemie
der Technischen Hochschule Karlsruhe (Germany)
Treatment of 2,5-diphenyl-3,4-diazanorcaradienewith active
precipitated manganese dioxide (E. Merck, Darmstadt) gives
cis-1,2-dibenzoylcycIopropane and nitrogen [I]. We have
Angew. Cheni. internat. Edit. Vol. 4 (1965) No. 11
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acid, synthesis, carboxylic, dichloroethylene
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