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Elimination Reactions of Trichlorobutyl Acetates.

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Elimination Reactions of Trichlorobutyl Acetates
11.83
By Giinther Maahs, Lutz Rohrschneider,
Peter-Jiirgen Frenzel, and Giinter Peitscher"'
Dedicated to Professor Franz Broich on the occasion of his
65th birthday
21.06
( 3 1 21
27L3
(27.5i
135.31
111
33 63
133.11
While the formation of chlorohydrin ethers and esters of
monoolefins has been studied extensively"], corresponding
investigations on diolefins have received little attention''!
In particular, reaction of diolefins and chlorine in the molar
ratio 1 :2 yields a rather complicated mixture of addition
and substitution products. We have prepared trichlorobutyl
acetates (chlorohydrinacetates of butadiene) and elucidated
their elimination reactions.
Table 1. Results of combined GC/MS analysis (Perkin-Elmer Fractometer F 6/MAT mass spectrometer CH 4).
26 92
I28 LI
31.9L
132 81
29.45
13111
17.L9
I19.Ll
Fig. 2. I3C-NMR shifts of cis-1,2-dimethylcyclohexane(I) at 158°K
and cis-1,4-dimethylcyclohexane(2) at 180°K; solvent CCI,F, t T M S
(5:l). 6 values in ppm downfield from T MS ; values in parentheses
shifts calculated according to Grant [2].
apparent from the diamagnetic shift of + 5.7 ppm (resulting
from mutual interaction of both groups in ( 1 ) ) in the case
of the axial group and of only + 2.3 ppm for the equatorial
group.
Identification of energetically unequal conformers and
determination of their equilibria is facilitated by 13C lowtemperature spectro~copy[~'.
The methyl signals of cis-4methylcyclohexanol at 200°K gave an equilibrium containing 7.704 with axial CH,. The resulting energy difference of the conformers is AG = 1.07 kcal/mol ; this
agrees with the value AG = 1 kcal/mol obtained by addition
of the conformational energies of CH, and OH groups,
which indicates that the groups separated in the molecule
exert no mutual interactions. This is confirmed by the
shifts of the methyl group which, at 6,,,=23.5 ppm or
6,,,= 17.6 ppm, do not differ from the values obtained for
cis-1,4-dimethylcyclohexane(2) and for methylcyclohexanei4]. When evaluating 13C-NMR spectra it should be
borne in mind that the signal intensities can be falsified by
differing relaxation times and Overhauser effects. That the
relative abundances are correctly reproduced for identically
substituted C atoms is shown, e.g., by integration of the
low-temperature spectrum of (2) to give area integrals for
stereoisomeric (exchanging) C atoms having deviations of
less than 0.5% for CH, and CH, and 4% for CH.
Peak
No.
Overall ret.
time (mini
Peak area
(%)
1
2
3
4
10.9
11.3
11.9
13.3
9.1
52.3
15.1
23.5
Rel. intensities ?/")
m/e
43
49
61 73
100
100
100
100
2.8
26
3.1
2.9
3.1
2.9
5.1
3.8
169
0.2
0.2
16.2
18.7
0.5
0.7
0.02
0.01
Chlorine is passed into a solution of butadiene in glacial
acetic acid (molar ratio C,H,:C1,=1:2)
in the dark at
15-18 "C in the presence of traces of oxygen. (Alternatively,
butadiene and chlorine can be passed simultaneously into
glacial acetic acid.) Distillation at 75-78"C/3 torr (116 to
12OoC/ll torr) gave a fraction (yield 25-35%;
nko
= 1.4783) that could be separated into four components
on a 50-rn polyphenyl ether capillary column at 175°C.
Relevant GC/MS data are listed in Table 1.
According to Table 1, components 1 and 2 and 3 and 4
appear to be very similar in the mass spectra, although the
two groups may readily be distinguished. The large proportion offragments havingmass number 73 (-CH'OCOCH,)
in components 3 and 4 suggests the presence of the I-acetate
(2) since the 2-acetate cannot possibly give this fragment.
Thus the reaction product consists of 61 "/, of the trichloro-
H H
H~C-C=C-CHZ
I
0
c1
I
+ C I i ~ C O O f I - 110
I
$0
Received: June 21,1971 ;
revised: July 9, 1971 [Z 462 IE]
German version: Angew. Chem. 83,759 (1971)
CH3
i
c I2
[I]H . Friebolin, W. Faist, H . G. Schmrd, and S . Kabuss, Tetrahedron
Lett. 1966, 1317, and literature cited therein.
[2] D. K . D a h g and D.M . Guanr, J. Amer. Chem. SOC.89,6612 (1967).
[3] J . B. Grutzner, M . Jautelat, J . B. Drnce, R . A . Smith, and J . D. Roberrs, J . Amer. Chem. SOC.92, 7107 (1970).
[4] ('I F A . L. Aner. C. If B r a d l q . and G. W Buchanan, J. Amer
Chem.Soc. 93,258 (1971).
[5] E . Lippmuu. T. Pehk, J . P a a s i i r i u , N . Beiikotia, and A . Plat@,J. Org.
Magnet Res. 2, 581 (1970).
[6] H:J. Schneider and W Breniser, Tetrahedron Lett. 1970, 5197.
Anzew. Chem. internat. Edit. 1 Vol. I0 (1971) / No. I0
[*I
Dr. G. Maahs, Dr. L Rohrschneider, Dr. P. J Frenzel, and
Ing. G. Peitscher
Forschungslaboratorien der Chemischen Werke Huls AG
437 Marl (Germany)
73 1
sec-butyl acetate [(1-chloromethyI-2,3-dichloropropyl)
acetate] ( I ) and 39% of the trichloro-n-butyl acetate [2,3,4trichlorobutyl acetate] (2) which are both composed of
two diastereomers.
The other distillation fractions were not studied. A white
solid crystallized from the high-boiling constituents (m. p.
o$ $0
H3C CHs
(3)
115-116°C from methylcyclohexane)which has the structure (3) according to its NMR and mass spectra.
The mixture of ( I ) and (2) was then treated in methanolic
solution with an equimolar amount of sodium methoxide
at room temperature. After the NaCI had been filtered off
1,3,6,8-Tetra-tert-butyl-9-carbazyl:
A Crystalline Monomeric Aminyl Radical['l["]
By Franz A . Neugebauer and Hans Fixher"]
Direct linkage of two ortho positions in diphenylaminyl
gives the 9-carbazyl system, a planar aminyl. In order to
determine the properties of 9-carbazyl radicals we have
synthesized the tert-butyl substituted carbazoles (1 a ) to
( I d ) and dehydrogenated them to give the 9-carbazyl
radicals (2 a ) -( 2d).
Reaction of carbazole (1 mol) with tert-butyl chloride
(6 mol) and AICI, (1 mol) at room temperature gives 1,3,6,8tetra-tert-butylcarbazole ( I a) (m. p. 191--192"C, 72%),
1,3,6-tri-tert-butyIcarbazole( I d ) (m. p. 136--137"C, 573,
and 3,&di-tert-butylcarbazole(m.p. 228-229"C, 10%)"s 'I.
1,8-Di-tert-butylcarbazole (1 b) (m. p. 173--174°C) is
obtained from ( I a) via 3,6-dinitro- (m. p. 289--29OoC),
3,6-diamino- (m. p. 254-255 "C), and 3,6-diiodo-1,8-ditert-butylcarbazole (m. p. 230-231 'C)13'. 1,3,8-Tri-tertbutylcarbazole (ic) (m.p. 131--132°C) can be prepared
similarly from ( l a ) by way of 3-nitro- (m. p. 227--228"C),
(2)
(1)
( a ) , R'
(b), R'
R 2 = R' = R4 = C(CH,),
R4 = C(CH3),; R 2 = R 3 = H
(c), R 1 = R 2 = R4 = C(CH,), ; R' = H
( d ) , R' = RZ = R3 = C(CH3),; R4 = H
"'"'"7-3
"1
=
=
A
3-amino- (m. p. 159-160 "C), and 3-iodo-l,6,8-tri-tertbutylcarbazole (m. p. 135-136°C)[31.
and the solvent pumped off, the residue was distilled at
57-70°C/10 torr (yield 60%, n;='
1.4790).
The product was separated into four components on a
preparative scale by gas chromatography. According to
the mass spectrum, the components are isomers of composition C,H60Cl,. The four cyclic structures ( 4 ) -(7)
were assigned on the basis of the NMR and I
R spectra.
The methanol removed from the reaction mixture was also
found to contain an equimolar amount of methyl acetate
with respect to the product.
The nucleophilic substitution therefore seems to lead to an
intramolecular elimination with ring closure. [The figures
in parentheses represent the limiting percentages of product
found for a variety of experimental conditions (reaction
time 10-120 min, reaction temperature 20-65"C, use of
methanolic potassium hydroxide).]
Received- June 30, 1971 [Z 464 I€]
German version: Angew. Chem. 83, 757 (1971)
f l ] Houben- Weyi-Miilier: Mefhoden der Organischen Chemie. 4th
Edit. G. Thieme Verlag, Stuttgart 1962, Vol. V/3, pp. 775ff.
[2] See, e. g., W Groshnik and R . A . Mallory, J. Amer. Chem. SOC.72,
4610 (1950).
732
Addition of an equivalent of iodine oxidizes a solution of
thelithium salt of(1 a) in benzene to thedeep blue(benzene:
h,,, = 660 nm, log E = 4.02) species 1,3,6,8-tetra-tert-butyl9-carbazyl ( 2 a ) which forms blue-black crystals (dec. p.
144--145°C) from light petroleum. Hydrogenation of ( 2 a )
with Pd/BaSO, in pyridine indicates a radical content of
92%. The extremely strong v(NH) band of the carbazole
( I a) at 3520 cm- ' is just detectable in the IR spectrum of
the radical (2a). Oxidation of the carbazoles ( I b ) - ( I d )
with lead dioxide in benzene also gives blue 9-carbazyl
Table 1. Coupling constants and spin densities for 9-carbazyl.
Position
1
2
3
4
4a
9
9a
EXP.[a1
Ia,lGl I
IP:l
3.8
0.9
4.3
0.15
0.16
0.038
0.18
0.006
-
6.9
-
Calc [4] [b]
-
0.24
-
P:
0.189
-0.053
0.152
0.023
0.073
0.284
- 0.026
[a] a" = -23.7 pc [ 5 ] ; aN = 28.6 pN [6].
[b] B C N = 1.2pcc; pC-43C--4b=0.8pCC;
a N = a c + 1 . 2 ~ c c ;h=1.2.
I'[
Doz. Dr. F. A. Neugebauer and H. Fischer
Max-Planck-Institut fur Medizinische Forschung
Abt. Moiekulare Physik
69 Heidelberg, Jahnstrasse 29 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
Angew. Chem. mternat. Edzt. 1 Vol. 10 (1971) J No. 10
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