close

Вход

Забыли?

вход по аккаунту

?

Metal-Catalyzed Synthesis of Cyclic Carbonates from Carbon Dioxide and Oxiranes.

код для вставкиСкачать
Table 1. Iy5Pt-NMRdata for some platinum-tin complexes [a].
28954
20410
9 067
trans-[PtH(SnCla)(PEt,)2J [fl
10955
truns-[PtH(SnCb)(PPh2CH2Ph)2][fl
tmns-[PtH(SnCI3)(PPh,)2l [fl
11512
I~u~~-[P~(C(CO,E~)==CHCOZE~)(S~C~~)(PP~~)Z]
[g]
11 320
-4780
-5152
- 5302
- 5322
-5195
-4771
1runs-[PtC1(SnC1~)(PEt~)~]
[c]
Irun~-[Pt(SnCl~)~(PEt,)~]
[d]
[a]
Chemical
shifts
rel.
-618 [el
- 426
- 428
- 354
- 469
external Na,PtCI,)
and coupling constants (in Hz).
CD2C12 at -40°C. [d] In (CD3),CO at - 50°C .
6[PtC12(PEt3)2]- 6[Pt(SnC13)2(PEt3)2]divided by 2. [fl In CD2C12at - 70 "C. [g] In CD2Cl2at room temperature.
(6
values
- 864
to
A8=6[PtX(SnC13)(PR3)2]-6[PtX(CI)(PR3)2].
[c] In
The differences between the IJ(195Pt"9Sn)values for the
series of complexes tr~ns-[PtH(SnCl,)(PEt~)~],trans[Pt(SnCl,),(PEt,),], and truns-[PtC1(SnCl3)(PEt3),] may be
understood in terms of the NMR trans influence series
(H > SnC13>Cl)l4].There is some precedence for the similarity of trans influence in carbon and hydride ligandsC4]so that
the coupling constants of 11512 Hz for trans[PtH(SnCl,)(PPh,),]
and
11320
Hz
for
trans[PtL(SnC13)(PPh3),],L = C(CO,Et)-CHCO,Et, appear reasonable.
The large absolute value of 1J(195Pt119Sn)
can be understood in terms of the Fermi contact expression used by Pople
and Suntry[?
The relatively large gyromagnetic ratios
y e for tin[61and
platinum combine with the relatively large expectation values
lP(0)12for heavy metals[71to afford a product which will be
much larger than for most nuclei. Thus, typical 'J('I9SnX)
values are: for X = ' H (Me,SnH), 1744 Hzl'"]; "P
(Me3Sn--PRR'), 460-832 HzLXbl;
,07Pb (Me3Sn-PbMe,),
3570 Hz[*"].Furthermore, the presence of the three electronwithdrawing chlorine substituents on tin are recognized to
result in an enhanced coupling ~onstant~'~.
This result stems
from an increase in nAB,
presumably due to an enhanced
amount of s-character in the metal-metal bond.
The values ~ 5 ( ' ~ ~are
P t )shifted to higher field by several
hundred ppm when a C1- ligand is replaced by SnCly
e.g. from -3916 for tran~-[PtCl~(PEt,)~],
to -4780 for
tr~ns-[PtCl(SnCl,)(PEt,)~]~.
This is in keeping with the exceptional sensitivity of 6 ("'Pt) to changes within the coordination sphere. It appears that 19'Pt-NMR spectroscopy will be
an extremely sensitive probe for molecular structure in this
catalytically active system.
Received: October 1, 1979 [Z 442 IE]
German version: Angew. Chem. 92, 323 (1980)
[l] H. Ituruni, J. C. Builur Jr., Int. Eng. Chem. Prod. Res. Develop. 1 1 , 146
(1972); I. Schwuger, J. E Knifton, J . of Catal. 45, 256 (1976); J. F. Knifton, J.
Org. Chem. 41, 793 (1976).
[2] Cf. P. S. Pregosin, S. N. Sze, Helv. Chim. Acta 61, 1848 (1978).
[3] We have recently learned that the complex (Ph3MeP)2[PtC12(SnC13)z]
shows
a 'J 195Pt"'Sn) value of 27646 Hz: J. H. Nelson, R. Rudolph, personal com(
munication, 1979. We find 6(I9'Pt)= -4212 (CD2CIZ)rel. to ext. Na2PtCk,
and 'J('95Pt"9Sn)= 27754 Hz for (Bu~N)~[P~CI~(SIICI,)~].
[4] T. C. Appleton, H. C. Clark, L. E. Munrer, Coord. Chem. Rev. to, 335
(1973).
[ 5 ] J. A . Pople, D. P. Suntry, Mol. Phys. 8 , 1 (1964); 9, 3 11 (1965).
[6] Both the 'I9Sn and "'Sn one-bond coupling constants are observed in the
Angew. Chem. Int. Ed. Engl. 19 (1980) No. 4
[b]
[el
Ig5Pt-NMRspectrum. The ratio 'J('95Pt''9Sn)/'J('y5Pt''7Sn)
is in agreement
with the ratio of their respective gyromagnetic constants.
171 P. S. Pregosin, R. W. Kunr in P. Diehl, E. Fluck, R. Kosfeld: NMR Basic
Prnciples and Progress, Vol. 16. Springer-Verlag, Berlin 1979.
[8] a) J. D. Kennedy, W. McFurlune, B. Wrockmeyer, Inorg. Chem. 15, 1299
(1976); b) H. Schumunn, H. J. Krorh, Z . Naturforsch. B 32, 876 (1977).
Metal-Catalyzed Synthesis of Cyclic Carbonates
from Carbon Dioxide and Oxiranes
By Michael Ratzenhofer and Horst Kischl']
The reactions of carbon dioxide are attracting renewed interest with regard to the use of readily available primary
chemicals in organic synthesis"]. Its reaction with methyloxirane (1) gives polycarbonates['] or the monomeric carbonate
4-methyl-1,3-dioxolan-2-one
depending upon the reaction conditions. All the catalytic processes known so far for
the synthesis of (2) operate at elevated C 0 2 pressure (5-200
atm) and elevated temperature (100-200 0C)13341.We now
wish to report catalysts that are active at room temperature
and normal pressure.
H 3 c b
+
c02
MX, /Lewis-Base
20'C.latm
t
4ch
O0K0
I21
Ill
Addition of (1) to a mixture of a metal halide and a Lewis
base under CO,, is shown by IR spectroscopy to lead to the
formation of (4, v(CO)= 1800 cm-l in (I). Pure (2) is ultimately isolated directly from the reaction flask by simple vacuum distillation. Thus the MoC15/PPh3catalyst system gave
the best conversions and yields at a molar ratio of 1:6 of the
components and a 100 to 200-fold excess of (1) relative to
MoCIS (see Procedure and Table 1).
The best catalysts were found to be mixtures of triphenylphosphane and the halides of aluminum, molybdenum, or
iron. Neither of the catalyst components on its own is able to
induce formation of (2). Transition metal compounds in low
oxidation states such as tr~ns-(N~),W(diphos)~or
CoC1(PPh3), fail to catalyze the reaction; however, the latter
compound does become active at high temperature and high
pressure131.
Preliminary mechanistic studies have been performed with
the AlCl,/Lewis base catalyst system: reaction of ( I ) with
["I
Priv.-Doz. Dr. H. Kisch, Dr. M. Ratzenhofer
Institut fur Strahlenchemie im Max-Planck-lnstitut fur Kohlenforschung
Stiftstrasse 34-36, 0-4330 Miilheim a. d. Ruhr 1 (Germany)
0 Verlug Chemie, CmbH, 6940 Weinheim, 1980
0570-0833/80/0404-0317
$ 02.50/0
317
Table 1. Activity of some catalyst systems for the synthesis of (2) from carbon
dioxide and (1) under normal conditions of pressure and temperature (7 d reaction time, in 10 ml of (1) as solvent).
MXJLewis base [a]
[MXJ
Imol/~l
AlCI,/PPh,
AICI,/NEl, (I :3)
AII,/PPh,
TiCIJPPh,
CrCIJPPh, (1 : 3)
MoC15/PBu,
MoCIJPPh, ( I :5)
MoCI,(C4HxO)3/PPh3
MoCI,/NEt,
WCI,/PPh,
FeC13/PPh3
CoCI2/PPhl ( I :5)
NiBrJPPh,
0.14
0.23
0.1
0.09
0.19
0.1
0.15
0.063
0.084
0.044
0.185
0.034
0.16
Turnover
n um ber [c)
Yield of
12) Ibl
47
52
46
15
46
32
67
24
and triphenylphosphane (11 g, 42 mmol) in a two-neck flask
under C 0 2 atmosphere. The solution is stirred for seven days
at room temperature and then vacuum distilled: unreacted
(1) (50 ml, 50%) distils over first, followed by the pure product (2) at b.p. 45-5O0C/O.1 torr; yield: 68.7 g (47% based on
weigh-in of (i), 94% based on reacted (I)); turnover number,
92 mol/mol MoC15. Experiments with other catalysts were
performed analogously.
<: 1
< 1
55
78
13
36
36
75
76
20
Received: April 4, 1979
supplemented: October 22, 1979 [ Z 423 IE]
German version: Angew. Chem. 92. 302 (1980)
79
76
31
61
29
58
32
18
[a] Molar ratio 1:6 unless stated otherwise. [b] Isolated product (W based on
weigh-in of ( I ) ) . [c] mol (2)/mol MX,.
AlC13 under argon is strongly exothermic and yields
[MeCH(Cl)CH,0]3A1[51.We found that this chloroalkoxide
takes up COz in the ratio of 1 : l ; the IR spectrum of the
product (KBr) shows strong bands at 1610 and 1430 cm-'
which are probably due to a metal alkyl carbonate formed by
insertion of CO, into one of the A1--0 bonds of the alkoxidel''. The dioxolanone (2) arises from the aluminum alkyl
carbonate only after addition of PPh3, pyridine, or NEt,. The
final reaction step occurs only in polar solvents such as tetrahydrofuran, oxetane, or methyloxirane.
The method described above is the simplest procedure
available for the synthesis of cyclic carbonates from carbon
dioxide and oxiranes. The disadvantage of the relatively long
reaction time of about seven days is offset by the advantages
of mild reaction conditions, very good yields (90-100%
based on reacted oxirane), and recovery of unreacted oxirane. On use of a chiral base, the catalyst system could in
principle permit a facile synthesis of chiral dioxolanones.
Preliminary experiments with MoCls and (R)-( +)-dimethyl1-(phenylethyl)amine, (+ )-brucine,
(R,R)-( -)-1,2-bis-
[ I ] Summary: M.E. Volpin, J . S. Kolomnikou, Organomef. React. 5, 313 (1975):
Pure Appl. Chem. 33, 567 (1973).
[2] W. Kuran, S. Pasynkiewkr, J. Skupiriska, Makromol. Chem. 178, 47 (1976).
[3] H. Koinuma, H. Kafo, H. Hirar, Chem. Lett. 1977, 517.
141 J. T. Dunn. US-Pat. 2773881 (1953);A. F. Millikan, US-Pat. 2993908 (1958);
G. W. Crosby, A. F. Millikan, US-Pal. 2994704, 2994705 (1958);K. Shimomura, S. Yafa, M . Gogo, C. Tsuno, Jap. 70 38,534(1970); Y. Fujira, T. Morimolo, Jap. 72 15,951 (1972);J. Harada. A. Kimura, J. Takeshrta, K. Wafanabe, H. Sugahara, lap. Kokai 77 03.064 (1977).
[5] Cf. F. Schmidt. Brit. Pat. 716126 (1955).
161 Cf. M. Hidai, T. Hikita. Y. Uchida. Chem. Lett. 1972, 521
171 We are grateful to Dr. L J . Wang for experimental cooperation, and to Dr. J.
Neuffer for providing chiral phosphanes.
Synthesis of the Epirneric 4-Methyl Derivatives of
endo-endo- and exo-endoTetracyclo (6.2.1.13-a.02-7]
d~decane~"]
By Dieter Lenoir and Robert M . Frank"]
The three isomeric tetracyclo[6.2.1.13.6.02.7]dodecanes
(i),
(2), and (3) (R, R = H ) were first used by Winstein et al. as
test compounds for examining steric hindrance as a result of
trans-annular H/H interactions[']. Subsequently, strain energies were estimated for the hydrocarbons by force field cal-
Table 1. Calculated standard enthalpies of formation and strain energies [4] (values in parentheses) for the isomeric tetracyclo[6.2.1.1 '~".O'-']dodecanes and norbornane and
their alkyl derivatives (values in kcal/mol). Inside, R=aIkyl, R ' = H; outside, R = H, R'=alkyl.
R
R'
endo-endo
compound
exo-endo
compound
(1)
(2)
6.12
4.82
- 0.57
- 6.64
- 11.42
- 7.34
- 17.71
Norbornane
(inside & endo)
(outside & exo)
- 2.92
- 4.97
- 9.45
- 16.98
- 18.48
- 17.35
(49.86)
(55.64)[a]
(50.25)[b]
(56.39)
(51.61)
(63.88)
(53.51)
(40.82)
(45.85)[c]
(41.37)[d]
(46.05)
(44.55)
(53.87)
-26.04 (45.18)
- 12.99 (16.98)
-19.15 (17.90)
- 20.01 (17.04)
[a] Identical with compound (12). [b] Identical with compound (6). [c] Identical with compound (15j. [dl Identical with compound (9).
(dimethylamino)cyclohexane, ( - )-2-menthyldimethylphosphane, ( +)-bis(2-menthyl)methylphosphane, and ( + )-2,2dimethyl-4,5-bis(diphenylphosphinomethyl)-l,3-dioxolane
("diop") have so far proved unsuccessful, h o ~ e v e r ~ ' ~ .
culations[zl and X-ray structure data were determined for
derivatives of endo-endo-(1) and of the exo-exo compounds
(3)[,I.
['I
Procedure
added
( l ) (loo ml, 1430 mmol) is
dropwise to molybdenum pentachloride (2.0 g, 7.3 mmol)
318
0 Verlag Chemie, GmbH, 6940 Weinheim. 1980
Pnv.-Doz. Dr. D. Lenoir, Dr. R. M. Frank
Organisch-chemisches Institut der Technischen Universitat Munchen
Lichtenbergstrasse 4, D-8046 Garching (Germany)
r*]
Results of Non-bonded Interactions, Part 1. This work was supported by the
Deutsche Forschungsgemeinschaft.
0570-0833/80/0404-0318
S 02.50/0
Angew. Chem. Int. Ed. Engl. 19 (1980) No. 4
Документ
Категория
Без категории
Просмотров
0
Размер файла
216 Кб
Теги
synthesis, dioxide, cyclic, metali, carbonates, oxiranen, carbon, catalyzed
1/--страниц
Пожаловаться на содержимое документа