close

Вход

Забыли?

вход по аккаунту

?

Diels-Alder Reaction of Cyclopentadiene with Acrylic Acid Derivatives in Heterogeneous Phases.

код для вставкиСкачать
171 V. G . Albano, P. Chini, S. Martinengo, M . Sansoni, D. S. Strumolo, J.
Chem. SOC.Dalton Trans. 1978, 459.
181 R. Masse. A . Simon, Mat. Res. Bull. 16, 1007 (1981).
191 a) Dr. A . Meyer, Stuttgart is thanked for the elemental analyses; b)
Gd5CIVC2 is monoclinic, space group P2,/c (No. 14), a=918.2(3),
b=1612.0(5), C = 1288.6(4) pm,/3= 119.86(2)";Z = 4 ; R=0.026 with 3539
reflexions I > 2 a (I).
Procedure
Diels-Alder Reaction of Cyclopentadiene with
Acrylic Acid Derivatives in Heterogeneous Phases
By Harun Parlar and Rotraud Baumann"'
In the addition of the acrylic acid derivatives (la)-(lc)
to cyclopentadiene in homogeneous phases, the isomeric
ratio of the products is hardly influenced by solvents or
catalysts"]; for the dienophiles acrolein (la) and methyl
acrylate (lb), the ratio of endo- to exo-adducts is ca. 3 :1,
and, in contrast, ca. 3 :2 for acrylonitrile (lc).
4
1)
K
~ O J ,
=
CHO,
( h i , R = COzCHs,
(3J
(0,
R = CN
Table I. Percentage composition of the product mixtures of the Diels-Alder
reaction of cyclopentadiene with acrylic acid derivatives absorbed on various
activated surfaces. The values in brackets refer to reactions on non-activated
surfaces [a].
(I)
Silica gel
Montigel
A1203
PI
(neutral)
(2)
(2)
(3)
(2)
(3)
43.9 47.3
27.7 68.9
(20.4) (79.6) (48.8) (51.2)
6.6 90.7
2.9 93.7
(b) 10.5 87.5
(13.2) (84.3) (12.9) (83.4) (2.8) (93.8)
25.9 67.2
37.0 60.3
(c) 32.8 50.4
(35.8) (60.1) (32.0) (65.0) (38.3) (58.1)
(a)
(3)
22.0 77.7
(19.2) (80. I )
Sea sand
Cellulose
(2)
(3)
(2)
13)
31.3 68.0
25.1 73.9
(22.6) (76.5) (26.7) (72.8)
23.5 71.1
24.3 71.4
(24.2) (72.2) (23.6) (72.5)
36.5 57.0
37.5 59.0
(38.0) (57.5) (36.7) (58.4)
[a] In homogeneous phases (2 h at 60"C), cyclopentadiene and (la), (lb).
or (Ic) give the following product ratios: (2a) :(3a)=24.4 :75.3;
(26):(36)=24.2:71.5; ( 2 c ) : ( 3 ~ ) = 4 0 . 2 : 5 8 . 2[b]
. Montigel is a natural montmorrillonite.
We have managed to achieve an isomer ratio of almost
I :1 in a purely heterogeneous reaction of cyclopentadiene
with acrolein (la) on non-activated neutral A1203. In the
addition of acrylonitrile (lc) to cyclopentadiene on activated Montigel, considerably more endo-isomer (3c) is
formed than in the same reaction under homogeneous conditions. Even more impressive is that the formation of the
exo-isomer is almost completely blocked in the reaction of
methyl acrylate (lb) with cyclopentadiene o n non-activated
Al2O3(Table 1). The isomer ratios are almost independent
of temperature (40-70°C). Mutual condensation of the
adducts can be excluded, since these are stable under the
same reaction conditions.
Measurements of the absorption behavior of the starting
materials at a maximal covering density of l o T 5particles/
cmz on a variety of surfaces, over different pressure and
temperature ranges, indicate that the chemical composition of the absorbent only influences the covering density
[*I Dr. habil. H. Parlar, R. Baumann
Institut fur Okologische Chemie
der Gesellschaft f i r Strahlen- und Umweltforschung mbH Miinchen
D-8050 Freising-Attaching (Germany)
1014
8 Verlag Chemie GmbH, 6940 Weinheim, 1981
to a small extent (the bond strength is 25 kcal/mol); any
special interaction of the educt with the surface, which
could result in reduction in the intramolecular interactions, is therefore precluded"'. Presumably, a small fraction of the molecules is strongly adsorbed on the surface.
Under these conditions one of the two transition states is
stabilized over the other by symmetry-controlled secondary orbital interactions[31.
Solutions of cyclopentadiene (0.05 mol), prepared by
thermolysis of dicyclopentadiene, and of the freshly distilled acrylic acid derivatives (0.05 mol), each in 50 mL of
diethyl ether, are taken u p successively on 30 mg of one of
the carrier substances at 20°C. After cautious evaporation
of the solvent at 35 "C at atmospheric pressure, the heterogeneous mixture is warmed up to 50°C for 4 h under constant stirring, and subsequently extracted (5 x 200 mL) with
acetone in a Soxhlet apparatus over 6 h. After removal of
the acetone under reduced pressure, the product mixture is
purified by passage through a short silica gel column (silica gel 60, Merck, l = 15 cm, d =4 cm, petroleum ether 609OOC). The product mixtures are analyzed by gas chromatography (glass column: 2 m, d=0.4 cm, 3% OV 17 on
Chromosorb W-AW-DMCS 80- 100 mesh, T=60"C, carrier gas: NZ,,50 mL/min).
Received: April 15, 1981 [Z 933 IE]
German version: Angew. Chem. 93. I I14 (1981)
CAS Registry numbers:
( l a ) , 107-02-8; (lb). 96-33-3;(Ic), 107-13-1; (2a). 19926-88-6; (26). 769-85-7;
(2c). 2890-96-2;( 3 ~ )19926-90-0;
.
(3b). 2903-75-5;( 3 4 . 2888-90-6; cyclopentadiene, 542-92-7.
( 1 1 K . Alder, G. Stein, E. Rolland, Justus Liebigs Ann. Chem. 525, 247
(1936); G. Calingaert. H . Soroos, H. Shapiro, Ind. Eng. Chem. 36. 1055
(1944); C . D. Ver Nooy, C . S. Rondestuedt. J. Am. Chem. SOC. 77, 3583
(1955); K . Alder, K . Heimbach, R. Reubke, Chem. Ber. 91. 1516 (1958);
W . R . Bohme. E. Schipper. W . G . Scharpf, J . Nichols, J. Am. Chem. SOC.
80, 5488 (1958); A . C. Cope. E. Ciganek. N . A . 12Be/. ibid. 81, 2799
(1959); N. A. Belikova. V. G. Berezkin. A . F. Plate, Zh. Obshch. Khim. 32.
2942 (1962);J. Gen. Chem. (USSR) 32, 2896 (1962);F. Kasper, Z. Chem.
5. 153 (1965); P. Wilder, D . B. Knighf. J. Org. Chem. 30. 3078 (1965).
121 W . Roth. Hoechst AG, Frankfurt, personal communication (1978).
131 R. B. Woodward. R. Hoffmann. J. Am. Chem. SOC. 87, 4388 (1965); Angew. Chem. 81, 797 (1969); Angew. Chem. Int. Ed. Engl. 8. 781 (1969).
Electrophilic Addition of a Sulfur, Selenium, and
Tellurium Atom as well as of an SO2 Molecule to
a Metal-Metal Bond'**'
By Werner Hofmann and Helmut Werner"]
We have recently shown that the dinuclear complex (1)
is nucleophilic~'"]. It reacts rapidly with CF3COOH, even
at room temperature, to give the cation (2) which has a
symmetric, bent CoHCo bridge. The CoCo bond lengths
in (1) and (2) (determinqd as BPh4 salt) are closely similar
[(I): 2.544 A; (2): 2.517 A]"b1. This indicates that the metalmetal interaction is little influenced by the protonation,
['I
[**I
Prof. Dr. H. Werner, Dr. W. Hofmann
lnstitut fur Anorganische Chemie der UniversitBt
Am Hubland, D-8700 Wiirzburg (Germany)
Basic Metals, Part 26. This work was supported by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, and,
through a gift of chemicals, by BASF AG, Ludwigshafen. E. Wittmann
is thanked for experimental work.-Part 2 5 : R . Feser. H . Werner. Angew. Chem. 92, 960 (1980); Angew. Chem. Int. Ed. Engl. 19. 940
(1980).
057i%0833/81/1212-1014 S 02.50/0
Angew. Chem. I n t Ed. Engl. 20 (1981) No. 12
Документ
Категория
Без категории
Просмотров
3
Размер файла
139 Кб
Теги
acid, acrylic, reaction, heterogeneous, alder, cyclopentadienyl, diels, phase, derivatives
1/--страниц
Пожаловаться на содержимое документа