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Hydrogenation of a Substituted Glutarodinitrile.

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However, even if only one ofthe substituents R’ and R2 is a
“planar” group (-NO,, carbonyl function), then a pronounced steric effect on the azobenzene group appears to
be prevented because these substituents relinquish their
coplanarity with the phenyl nucleus I in order to avoid
hindrance by the azo bridge [ ( I ) , (10)-(14)].
This explanation is supported by the observation that with
such substituents the bathochromic influence at position 4
to the azo group is greater than at position 2 [ ( I S ) ,
(27)-(29), (I)] while in the case of spherical or tetrahedral
substituents it is almost equal at positions 2 and 4
[f 181-(26)1.
‘
Steric effects are not brought about by substitution with
nitrile groups. The hypsochromic shift in 2,6-substituted
azobenzenes is considerably reduced when there is no
nitro group at position 4 (R3) [compare ( l a ) , (21), (33)
with ( I ) , ( 4 ) , (5)J
Table I.Absorption (XmJ and extinction maxlma ( E ) of the s-n* bands
of azobenzenes of formula A (in methanol). The compounds whlch were
purified by column chromatography and recrystallization were homogeneous on thin-layer chromatography and afforded correct elemental
analyses.
H
CHI
CH3
CI
CI
CF3
CF3
SOzCH,
S02CH3
COCbHs
COCsHs
NO2
NO2
NO2
CN
CN
CN
H
CH3
H
CI
H
CFa
H
SOzC2Hs
H
COCbHs
H
NO2
CN
H
NOz
CI
[a] Bridgeman and Peters
ments in ethanol.
H
H
CH3
H
CI
H
Br
H
Br
H
Br
H
Br
NOz
H
CN
Br
H
H
H
H
H
H
H
H
H
H
H
H
H
H
NO2
CI
NO2
NO2
NO2
NO2
NO2
N0z
NOZ
N0z
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
H
H
CH3
H
CI
H
‘ 3 3
H
SOzC2H5
H
COCaHs
H
H
CN
H
H
181 obtained
453
454
383
475
417
480
423
500
433
482
503
49 1
498
520
504
549
506
399
402
399
412
409
416
416
429
430
419
432
425
434
433
450
396
44000
42000
24 000
40000
31000
44000
26000
35 000
30 000
40000
41 000
38000
34 000
48000
45000
38000
37 000
40000
I8000
53000
37 000
42000
34000
41 000
45000
40000
36000
43000
36000
42 000
45 000
27 000
22000
the same results from measure-
As shown in Table 1, steric hindrance is strikingly evident
in the position of k,,,,, when (i) R’ and R2 are bulky
substituents and (ii) a strongly polar azobenzene system
capable of mesomerism is involved. A qualitative explanation has been given previouslyr6’ for similar relations in
the stilbene steries.
n
B
Angrw. Chem. internat. Edit.
C
1 Vol. 12 (1973) 1 No. I 1
A planar trans-azobenzene with one substituent on C-2
can assume conformation B or C, that of C being sterically
more favorable than that of B. Thus stronger steric hindrance is to be expected only when C-2 and C-6 of one
benzene ring are both substituted so that one substituent
necessarily overlaps the sp2 electrons of the P-nitrogen
atom. In strongly polar azobenzenes of type A, R 3= N 02,
quinonoid structures such as A’ contribute more to the
mesomerism than in less polar azobenzenes and this leads
to shortening of the distance between the substituent and
the P-nitrogen atom.
Since A is more strongly involved in the excited state
than in the ground
the steric hindrance is greater
in the excited than in the ground state and a short-wave
shift of the n-x* bands is always produced.
Received: September 5, 1973 [Z 916 IE]
German version. Angew. Chem. 85,984 (1973)
[l] J . M . Robertson, J . Chem. SOC.1941,409
[2] P. H . Gore and 0.W Wheeler, J. Org. Chem. 26. 3295 (1961).
[3] E. Hasrfbuch and E. Heifhronnrr, Helv. Chim. Acta 5 1 , 16 (1968)
[4] S. Yurnarnoro, N . Nishimura, and S. Hasegawu, Bull. Chem. SOC.
Jap. 4 4 , 2018 (1971).
[5] D. Grgrou, K . A. Muszkat. and E. Fischer. J. Amer. Chem. SOC.
90, 3907 ( 1968).
161 R. N . Beafe and E . M. F . Roe, J. Amer. Chem. SOC. 74, 2302 (1952).
[7] H . A. Staah: Einfuhrung in die theoretische organische Chemie.
Verlag Chemie, Weinheim 1970, 4. Edit.
[8] J . Bridgeman and A. 7: Peters, J. SOC.Dyers Colour. 86, 519 (1970).
Hydrogenation of a Substituted Glutarodinitrile
By I . Leupold and H . 4 . Arpe“’
Dedicated to Professor Werner Schultheis on the occasion
of his 70th birthday
Suitably substituted diamines with at least four C atoms
between the amino groups are desirable starting materials
for preparation of transparent polyamides by condensation
with dicarboxylic acids. Economic access to them is provided by dinitriles since these can be hydrogenated to
diamines by use of cobalt catalysts and a large excess
of NH3. By-products are obtained owing to loss of
ammonia, e. g. pyrrolidines and piperidines from the parent
succinodinitriles and glutarodinitriles, respectively‘” ’I.
Thus on catalytic hydrogenation of 2-( l-cyclohexenyl)-3,3pentamethyleneglutarodinitrile ( 1 ), the diamine ( 3 ) and
the piperidine derivative ( 4 ) are both obtained, but in
addition the partially hydrogenated amino nitrile (2) can
also be isolated. Any one of the products (2), (3) and
( 4 ) containing an irreducible double bond can be made
to preponderate by choice of reaction conditions (see
Experimental).
The primary nitrile group is more easily hydrogenated
than the secondary one, so that, with simultaneous migration of the double bond into conjugation, 2-cyclohexylidene-3,3-pentamethylene-5-aminovaleronitrile(2), m. p.
148“C, can be obtained under mild conditions of hydrogenation. Since cyclization to 1-(l-cyclohexenyl)-3-azaspiro[5..5]undecane ( 4 ) , m. p. 50°C, is hindered by the bulky
cyclohexane rings, 2-( 1-cyclohexenyl)-3,3-pentamethylene1,5-pentanediamine ( 3 ) , m. p. 5 9 T , is formed preferentially below 150”C, the double bond migrating back to
its original position. At higher temperatures ( 4 ) is the
main product. This reaction opens an easy route to a
3-azaspiro[ 5.5lundecane.
[*] Dr. I. Leupold and Dr. H.-J. Arpe
Farbwerke Hoechst AG
623 Frankfurt/Main 80 (Germany)
927
Separation of the products was by chromatography with
ethanol/conc. NH3 (4:1) on silica gel. The products are
eluted in the order (2), ( 4 ) , (3). The structures assigned
accord with C, H, N and 'H-NMR, IR and MS data.
Received: September 5, 1973 [Z 917 IE]
German version: Angew. Chem. 85,985 (1973)
[I] R. L. Augustine: Catalytic Hydration. Dekker, New York 1965.
[2] Brit. Pat. 576015; Chem. Abstr. 42. 591 (1948).
[3] H:J. Arpe and I . Leupold, Angew. Chem. 84, 767 (1972); Angew.
Chem. internat. Edit. I I , 722 (1972).
Removal of Ally1 groups by Formic Acid Catalyzed
by (Tripheny1phosphane)palladium
By H . Hey and H . 4 . Arpe"
Dedicated to Professor Werner Schultheis on the occasion
of his 70th birthday
In the presence of (tripheny1phosphane)palladium
catalysts, allyl phenyl ether and allyl carboxylates react
with carboxylic acids by exchange of the allyl group for
the acidic H of the
The formation of ( 4 ) probably occurs by intramolecular
amine-imine addition and hydrogenative deamination by
way of the unisolated intermediates (2a) and (2b). This
is indicated also by smooth reaction to give the piperidine
( 4 ) when the individual compounds (2) and (3) are hydrogenated at about 200°C.
Experimental
(6Og)is shaken in a 1-1 V4A autoclave with a hydrogenation catalyst ( 5 g), containing 39wt.-% of cobalt as
(
T [ C]
Solvent [g]
(21
100
I30
200
Yields [moI-%]
(3)
(4)
61
150 Dioxane, 75 NH3
100 NH,
150 Dioxane
10
< 1
35
75
< 1
2
6
97
C6H50-Allyl
+ R'COOH
C6HrOH + R'C00-Ally1
RC00-Ally1
+ R'COOH
RCOOH
However, in an attempt to obtain allyl formate in this
way from allyl acetate and formic acid, the starting materials decomposed to acetic acid, C 0 2 and propene.
CH3C00-Allyl
+ HCOOH
3CHJCOOH + C 0 2 + H-Ally1
This reaction can be applied also to other allylic and
substituted allylic compounds (Table I).
Table 1. Examples of the removal of allyl groups by formic acid. Typical
experiment: A solution of palladium acetate (112 mg, 0.5 mmol) and triphenylphosphane (1.572 g, 6.0 mmol) in allyl acetate (75 g, 0.75 mol) was
treated under argon with formic acid (11.5 g, 0.25 mol) and warmed to
90°C. Rapid evolution of gas began at 70°C and was complete within 1 h.
The solution contained, besides catalyst and unchanged allyl acetate,
0.24 mol of acetic acid, and the gas contained 48 vol.-% of CO,, 50 vol.-%
of propene and 1 vol.-% of H, (from decomposition of formic acid).
Starting materials
Ally1 cpd.
[moll
HCOOH
[moll
Liquid
products
allyl propionate 0.4
allyl phenyl ether 0.36
methallyl acetate 0.41
2-butenyl acetate 0.4
0.05
0.05
0.05
0.05
propionic acid
phenol
acetic acid
acetic acid
cinnamyl acetate 0.2
0.2
triallylamine
0.05
01
acetic acid
I-phenylpropene 0 08
3-phenylpropene 0 02
diallylamine, allylamine
and other products
0.49
+ R'C00-Ally1
[moll
0.05
0.04
0 05
0.05
Gaseousproducts [a]
olefin
co2
[vol.-%]
propene49
propene47
isobutene 48
1-butene 34,
trans-2-butene 7,
cis-2-butene 2.5
propenel7
H,
51
52
52
56
74
26[bJ
50
32[b]
~~
[a] Measured in a sample of the gas.
[b] Formed by decomposition of formic acid.
well as S O 2 , at a hydrogen pressure of 200atm for 24h,
with the tabulated results.
928
[*] Dr. H. Hey and Dr. H.-J. Arpe
Farbwerke Hoechst AG
623 FrankfurtiMain 80 (Germany)
Angew. Chem. internaf. Edit. / Vol. 12 (1973) 1 No. i f
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