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Clays Direct Aromatic Nitration.

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3.1 8' [ l o ] ) and the widening of the intracyclic angle at C, .
Open-chain q3-I,3-diphosphaallyl complexes show smaller
P-C-P angles." '1
The quantitative conversion of 2 into 4 (31PNMR) opens
up several new perspectives: (1) the easy variation of the
substitution pattern of 4 via the choice of the starting 1,2diph~sphete;[~l
(2) the optional ql-coordination of the two
phosphorus atoms of these unhindered 1,3-diphospholide
species (such a coordination appears to be difficult in the
case of the strongly hindered 2,4,5-tris-tert-butyl derivative[81);( 3 ) the 2-H atom the 1,3-diphospholide ligand in
q5-complexes such as 5 could be substituted. We are currently investigating these possibilities.
Experimental Procedure
Synthesis of 2a, 2b: The P-P bond of 1 (3.94 g, 10 mmoles) was cleaved under
an argon atmosphere by stirring with lithium (140 mg, 20 mmol) in 20 mL of
T H F for 3 h. The solution was then cooled to - 80 "C and one equivalent of CS,
(600 pL, 10 mmol) was added. After fifteen minutes, two equivalents of methyl
iodide (1.24 mL, 20 mmol) were added dropwise. After stirring for an additional fifteen minutes at - 8 0 ° C the reaction mixture was slowly warmed to room
temperature. After evaporation of THF, the mixture was chromatographed
over silica gel 60 with hexaneltoluene (50150) to remove any unconsumed 1, and
then with toluene. About 10% unconsumed 1 was thus recovered and 80%
pale yellow crystals of a mixture of the two isomers 2a and 2b.
Synthesisof5: Asolutionof2(2 g.4 mmoles)in20 mLofTHFwasstirred with
170 mg (24mmol) of lithium wire (1% Na) under an argon atmosphere for
24 h at room temperature. The product 3 was treated with 1 mL (12 mmol) of
rBuCl and the reaction mixture left to stand for an additional 24 h, thus yielding
4. Finally, 4 was allowed to react with 1.5 g (4 mmol) of [CpFe(C,H,,)IePF:
at room temperature for 4 h to yield 5. The reaction mixture was quickly
chromatographed on a short silica gel column (20 g, I = 8 cm, Q5 = 26 mm) and
eluted with CH,Cl,. After evaporation of the solvent, the residue was chromatographed a second time over silica gel (100 g, l = 21 cm, @ = 36 mm) and
eluted with a mixture of hexane and CH,Cl, (70/30). The expected product 5 is
obtained with the bright red head fraction, yield 41 YO.5 can be purified by
heating under vacuum (0.1 torr) in a sublimer at 120°C to remove an oily
residue that cannot be removed by chromatography. 5 can be recrystallized
from a mixture of toluene and methanol (5195).
equal to 1.3 times that of the attached carbon atom while using anisotropic
temperature factors for all other atoms. A non-Poisson weighting scheme
was applied with a p factor equal to 0.08. The final R factors were
R = 0.047, R w = 0.064, G.O.F. = 1.27. Further details of the crystal structure investigation are available on request from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich-technische Information mbH, D-7514 Eggenstein-Leopoldshafen 2(FRG), on quoting the
depository number CSD-54551, the names of the authors, and the journal
[lo] F. Mathey, A. Mitschler, R. Weiss, J. Am. Chem. Soc. 99 (1977) 3537.
[11] R. Appel. W. Schuhn, F. Knoch, Angew. Chem. 97 (19x5) 421; Angew.
Chem. lnt. Ed. Engl. 24 (1985) 420.
Clays Direct Aromatic Nitration **
By Christine Collet, Alfred Delville, and Pierre Laszlo *
Dedicated to Professor Paul von Rague Schleyer
on the occasion of his 60th birthday
Modified clays can act as efficient catalysts of organic
reactions." 31 Among clays, kaolinites have seldom been
used for such purposes,[21 although they do intercalate
molecules as polar as water,141 formamide,['] N-methylformamide,'51 dimethyl sulfoxide,I6.'I and dimethyl selenoxide[71within their layers. Therefore, we set about exploring the catalytic potential of kaolinites for reactions proceeding through highly polar transition states. Discrimination
between transition states differing in polarity and in steric
bulk was our goal. We chose to study the nitration of p-anisaldehyde (1).
CCI,, Ac,O
Received: November 30, 1989 [Z 3661 IE]
German version: Angew. Chem. I02 (1990) 575
CAS Registry numbers.
1, 96693-28-6: 2a. 126134-65-4; 2b, 126134-66-5; 4, 126134-67-6, 5, 12613468-7, [CpFe(C,H,,,)IePFF. 34978-37-5
[l] R. Bartsch, P. B. Hitchcock, J. F. Nixon, J: Chem. Soc. Chem. Commun.
1987. 1146.
[2] A. H. Cowley, S . W Hall, Polyhedron 8 (1989) 849.
[3] R. Bartsch, J F. Nixon. Polyhedron 8 (1989) 2407.
141 L. Ricard, N. Maigrot, C. Charrier, F. Mathey. Angew. Chem. 99 (1987)
590: Angen.. Chem. Int. Ed. Engl. 26 (1987) 548.
[5] C. Charrier, J. Guilhem, F. Mathey, J. Org. Chem. 46(1981) 3; C. Charrier,
N. Maigrot, E Mathey, F. Robert. Y. Jeannin, Organometallics 5 (1986)
[6] C. Charrier, F. Mathey Tetrahedron Lett. 28 (1987) 5025.
[7] The reaction of cationic (qs-cyclopentadienyl)(qb-arene)ironcomplexes
with phospholide anions yields the corresponding monophosphaferrocenes: R. M. G. Roberts, A. S . Wells, Inorg. Chim. Acra 112(1986) 171.
[8] R. Bartsch, P. B. Hitchcock, J. F. Nixon, J. Organomet. Chem. 340 (1988)
[9] Crystals of5, C,,H,,FeP, were grown at - 18 "C from a methanol-toluene
solution of the compound. Data were collected at 18" i. 1" on an Enraf
Nonius CAD4 diffractometer. The crystal structure was solved and refined using an Enraf Nonius CAD4 diffractometer. The compound crystallizes in the space group P2,/n, a = 10.194(1) A, b = 9.841(1)A,
c = 16.818(1) A, B = 95.05(1)"; V = 1680.710 A3;Z = 4, e..i.d= 1.487 g/
cm3; Cu,, radiation (1. = 1.54184 A) graphite monochromator; p =
90.6 cm- '; F(000) = 768. A total of 3683 unique reflexions were recorded
in the range 2" < 2q < 150.0", of which 1683 were considered as unobserved (F2 < 3.Oo(F2)), leaving 2000 for solution and refinement. The
structure was solved by direct methods, yielding a solution for 12 of the 23
heavy atoms. The hydrogen atoms positional parameters were refined in
the final stages o f a least-squaresrefinement with fixed thermal parameters
Angew Chem. Int. Ed. Engl. 29 (1990) No. 8
The methoxy substituent directs nitration to the ortho and
para positions.['] In the former case, the resulting Wheland
intermediate has only to lose a proton for product 2 to be
formed. In the latter case, that of nitration ips0 to the 4formyl-substituted position, expulsion of protonated carbon
monoxide is a prerequisite for the appearance of product 3.
Accordingly, under homogeneous reaction conditions, only
minuscule quantities of the minor 3 form (Table 1). The two
''I leading to products 2 and 3 are
highly polar, with calculated dipole moments (MINDO3[15])of 4.49 and 5.57 D, respectively. Accordingly, the expectation that the high acidity (Hammett acidity function
Ho = -6 to -8)[16' and perhaps also the intense electric
field at the interface of a montmorillonite clay ',
favor the 1 - 3 pathway was borne out (Table 1): in the
presence of montmorillonite K10" 31 the proportion of3 in
the product mixture 2 3 goes up by more than one order
of magnitude, and increases as the Brernsted acidity at
Prof. Dr. P. Laszlo, C. Collet, Dr. A. Delville
Laboratorre de chimie fine aux interfaces
Universite de Liege
Sart Tilman par B-4000 Liege (Belgium)
and Ecole Polytechnique,
F-91128 Palaiseau (France)
We thank Professor Jacques Thorer and Mr. Diano Antenucci. University
of Liege, for the X-ray diffractograms
Verlugsgesellschafi mhH. 0-6940 Weinheim, 1990
Table 1. Proportion of p-nitroanisole formed ( f 1 . 2 % ) as a function of the
solid present (0.15 g per mmol of l)[a].
Solid support
3 (Oh)
Cu(NO,), . 3 H,O on kieselguhr
Cu(NO,), . 3 H 2 0 on acidic alumina
Cu(NO,), . 3 H 2 0
K 1O-Cuze
K ~ o - z ~ ~ ~
3 -6
27 P I
[a] 1.5gofthesolid + 10mmol1 + 3.1 mlAc,Oi.e.anexcessrelativetoHNO,
plus the residual water in the clay [12] are introduced in that order in CCI,
(25 ml) and retluxed for 15 min while 0.5 mL of fuming HNO, (Merck, p.a.,
99.5% min.) is added dropwise. [b] 73% of 2. Claycop is clay-supported cupric
nitrate [3]
the surface is enhanced by the Lewis-acidic interstitial
cations.[' - Likewise, in a still more pronounced manner,
a kaolinite, also a clay with a strongly acidic surface
(Ho = -3 to -6),[16] favors ips0 nitration: the yield of 3
rises to 27 %, boosted by a factor of 25 compared to homogeneous conditions!
The percentage of 3 varies with the amount of kaolinite
present (Fig. 1): such a plot, with a strong resemblance to a
Langmuir isotherm, is consistent with a single type of cata-
CAS Registry numbers.
1, 123-11-5; 2, 31680-08-7; 3, 100-17-4, Kaolinite, 1318-74-7
[l] P. Laszlo Science 235 (Washington D. C.) (1987) 1473-1477.
[2] P. Laszlo in P. Laszlo (Ed.): Preparative Chemistry Using Supported
Reagents, Academic Press, San Diego 1987, p. 3
[3] A. Cornelis, P. Laszlo Aldrichimica Acta 21 (1988) 97-103.
[4] a) P. Costanzo, R. F. Giese, M. Lipsicas CIays Cfay Miner. 32 (1984)
419-428; b) M. Lipsicas, C. Straley, P. Costanzo, R. F. Giese, J. Colloid
Interface Sci. 107 (1985) 221 -230.
(51 M. Lipsicas, R. Raythatha, R. F. Giese, P. Costanzo, Clays Clay Mmer. 34
(1986) 635-644.
[6] J. G. Thompson, C. Cuff Clays Clay Miner.33 (1985) 490-500.
[7] M. Raupach, P. F. Barron, J. G. Thompson Clays Clay Miner. 35 (1987)
208 - 219.
[8] K. Schofield: Aromatic Nitration, Cambridge University Press, Cambridge
[9] Aromatic nitration ofan activated substrate such as 1 has a late transition
state resembling the Wheland intermediate [8], a statement not overturned
by recently proposed SET mechanisms [lo].
[lo] a) C. L. Perrin J. Am. Chem. Soc. 99 (1977) 5516-5518; b ) L. Eberson, F.
Radner Acc. Chem. Res. 20 (1987) 53-59; c) M. J. Thompson Tetrahedron
45 (1989) 191-202; d) J. F. Johnston, J. H. Ridd, J. P. B. Sandall J. Chem.
Soc. Chem. Commun. 1989, 244-246.
[ I l l The proportion of 3 formed is identical when the reaction is run either
under dinitrogen or carbon monoxide pressure (20 bar); which rules out
carbon monoxide loss in the rate-determining step.
[12] Acetic anhydride plays a role in dehydrating both the clay and the nitrating
agent. Under such conditions [13], acetyl nitrate is the likely nitrating
species 1141. Furthermore, acetic acid could serve as the base and pull off
a highly acidic proton, the pK. of its conjugate acid being 0.58 in H,SO,.
[13] J. B. Menke Reel. Truv. Chim. Pays-Bas 44 (1925) 141-149.
[I41 M. A. Paul J. Am. Chem. Soc. 80 (1958) 5332-5333; A. Cornelis, L. Delaude, A. Gerstmans, P. Laszlo Tetrahedron Lett. 29 (1988) 5657-5660.
[15] R C. Bingham, M. J. S. Dewar, D. H. Lo. J. Am. Chem. Soc. 97 (1975)
1294- 1301.
Am. Chem. SOC.78 (1956) 5490-5494.
[I61 H . A. Benesi .
[17] The magnitude of the electric field was calculated from Gauss's law, at a
distance of 6 A from a clay sheet with a charge density, appropriate for a
The electric field at the
smectite (the Upton bentonite) of 6.8 me .k2.
interface has limiting values of 1.6 x lo8 V m - ' for a dielectric constant of
78.5(water), andof1.2 x 10'oVm-' foradielectricconstantofunity.The
energy gain for the more polar of two transition states differing by 1 D in
their dipole moments is 5.5 kJ mol-' for a local dielectric constant of 5.
[18] The Bertran group has shown recently that strong electric fields of ca.
10" V m- ' can remove an activation energy barrier. They showed, using
the example of the FR CH,F Walden inversion, that increasing the
strength of the electric field gradually deletes the barrier [19]. The heuristic
interpretation is that electrons donated by the nucleophile follow the field
which pumps the system from its initial to its final state.
1191 J. L. Andrks, A. Lledbs, M. Duran, J. Bertran Chem. Phys. Lett. 153(1988),
[20] Source Clay Minerals Repository, Department of Geology, University of
Missouri Columbia, Missouri 65201 (USA). BET specific surface = 8.8 mz . g-'.
[21] X-ray diffractograms of the kaolinite are identical before and after the
Kaolinit 1 [g rnoi-ll
Fig. 1. Percentage of 3 formed as a function of the ratio (g mol- ') of the mass
of kaolinite (g) to the amount of 1 (mol)
lytic site. In the most conservative estimate, the catalytic
turnover is at least 300.[201The enhanced production of 3 is
observed only with phyllosilicates, such as the K10 montmorillonite and kaolinites. Conversion is quantitative when the
amount of the nitrating reagent has been well-adjusted to
equal that of the aldehyde substrate, taking into account
(minor) losses as vapors of nitrogen oxides. Conversion does
not occur significantly (Table 1) on the surface of microporous solids such as alumina or silica.
These effects do not seem to require intercalation.[z11Protonation of the incipient carbon monoxide leaving group,'' ']
in the adsorbed state, is the probable cause for the considerable increases in the amount of ips0 nitration in the para
position, by a factor 10 with the montmorillonite, and by a
factor 25 with the kaolinite.
Received: November 13, 1989 [Z 3630 IE]
German version: Angew. Chem. 102 (1990) 563
firlagsgesellschaft mbH, 0-6940 Weinheim. 1990
Formation of an Aminoreductone from Glucose
By Sabine Estendorfer, Franz Ledl,* and Theodor Severin *
In many heated foodstuffs, reducing sugars react with
amino acids or proteins to give, inter alia, brown products
and characteristic aromas of roasting (non-enzymatic
browning, Maillard reaction). Such reactions have for some
time attracted interest among physicians and biochemists,
since one presumes that morbid alterations in diabetic per[*] Prof. Dr. T. Severin, S. Estendorfer
Institut fur Pharmazie und Lebensmittelchemie der Universitat
Sophienstr. 10, 8000 Miinchen 2 (FRG)
Prof. Dr. E Led1
Institut fur Lebensmittelchemie der Universitlt
Pfaffenwaldring 55, 7000 Stuttgart 80 (FRG)
Angew. Chem. Int. Ed. Engl. 29 (1990) No. 5
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clay, direct, aromatic, nitration
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