вход по аккаунту


NMR Spectroscopic Investigation of Intercalation Compounds of Organic Molecules and Sheet SilicatesЧp-Xylene-Hectorite and Related Systems.

код для вставкиСкачать
CAS Registry numbers:
( I ) , 75993-80-5; (1) radical cation, 75993-81-6; (2). 75993-82-7; (2) radical cation.
75993-83-8: (31, 71691-01-5; (3) radical cation, 75993-84-9
[I] For the structurally related Rydberg-state of the neutral ethylene. a twist by
2 5 2 I " of the CH,-groups was derived from the electronic spectrum: A. J.
Merer. L. Schoonueld, Can. J . Phys. 47, 1731 (1969).
[2] See. e-g., W. A. Lothan, W. J. Hehre, J. A . Puple. J. Am. Chem. SOC.Y3. 808
131 See. e.g . W. Rodwell. M F. Cue% D. T. Clark. D. Shuttleworth. Chenl. Phys.
Lett. 45. 50 (1977).
141 The compounds ( 1 ) and (2) were synthesized analogously to /3):cf. IS).
151 A . Krebs, W. Ruger, Tetrahedron Lett. 1979, 1305.
[6] Working electrode: Pt; reference electrode: Ag/O. 1 M AgNO,/CH,CN. Solvent: CH,CN: supporting salt: LiCIO..
[7] Limits of error: -+0.001 mT for (I and +0.0001 for g. ENDOR signals for
( 3 ) : in CH2Cl2at 193 K: 10.96 s. 13.42 w, 14.19 w, and 16.64 s MHz: frequency of the free proton: 13.80 MHz.
[S] H . Ohya-Nishiguchr, Bull. Chem. SOC.Jpn. 52. 2064 (1979).
191 U. Burkerr. Tetrahedron. in press; D. Lenoir. H.Duuner. R. M Frank. Chem.
Ber. 113, 2636 (1980)
TGA readily reveal the degree of uptake and extent of c-axis
expansion that accompanies the formation of these intercalates. High-resolution 'H- and '3C-NMR spectra were obtained using a conventional Varian CFT-20 spectrometer at
80 MHz and 20 MHz, respectively. Both proton and carbon
spectra were obtained using a spinning sample. The proton
spectral widths were such that no extra proton decoupling
power in addition to the 3 kHz available from the basic spectrometer was necessary to obtain l3C spectra at ambient temperature.
Typical spectra of powdered specimens of the organic intercalates at 30°C are shown in Figures 1 and 2. Although
the proton peaks are rather broad they are much narrower
than would be obtained from solid p-xylene or solid y-butyrolactone, indicating that these organic molecules have considerable freedom of motion in the interlamellar region. The
NMR Spectroscopic Investigation of Intercalation
Compounds of Organic Molecules and Sheet
Silicates-p-Xylene-Hectorite and Related
1 000 Hz
By Colin A . Fyfe, John M. Thomas, and
James R. Lyerlal'l
Many categories of sheet silicates are known to be capable
of taking up, within their interlamellar spaces, a wide range
of organic
The majority of these "organic"
intercalates break down upon heat-treatment simply to yield
the separate parent materials, but it has of late become increasingly apparent that several, highly selective chemical
c o n v e r s i ~ n s41~ can
' ~ ~ be
~ ~carried out through the agency of
such intercalates. In elucidating the nature of the microenvironment to which the organic molecule is exposed in the interlamellar region little use has so far been made of NMR
spectroscopy, even though this technique has already proved
illuminating in probing the properties of clay: water systems['], and also in clarifying the nature of adsorbed organic
molecules at exterior surfaces (of ZnO for example[6"]),of organic clathrates[6b1and of small organic molecules, such as
methanol, in zeolites and silica gell'"].
We here report how, using a commercially available
pulsed FT-NMR spectrometer, it is possible to assess (i) the
degree of molecular freedom, (ii) the composition of mixtures and (iii) the keto-enol equilibrium of certain organic
species retained in the interlamellar spaces of a synthetic
hectorite-idealized formula Nao67Si8(MgS33Lio67)010(0H)4.
Experimental methods for preparing a range of room-temperature stable intercalates of hectorites (and of montmorillonites) are given elsewhere171. X-Ray diffractometry and
Fig. I . A) 'H-NMR spectrum of thep-xylene-hectorite intercalate at 80 MHz (50
pulses). The vertical arrow indicates the position of a small, sharp peak arising
from HOD impurity in the D,O lock reference which has been deleted for clarity
(see also Fig. 2A) B) "C-NMR spectrum of the same intercalate at 20 MH7.
(4000 pulses).
1 000 Hz
['I Prof. C. A. Fyfe
Guelph-Waterloo Centre for Graduate Work in Chemistry
University of Guelph
Guelph. Ontario N1G 2W1 (Canada)
Prof. J. M. Thomas
Dept. of Physical Chemistry, University of Cambridge
Lensfield Road. Cambridge CB2 IEP (England)
Dr. J . R. Lyerla
IBM Research Laboratories
Monterey & Cottle Roads. San Jose, California 95 193 (USA)
This work was initiated when two of us (J. M. T. and C. A. E ) were visiting
scientists at IBM. San Jose. We are grateful to IBM and particularly to Dr
G . Castro for their hospitality and support, and also to the Science Research
Council (U. K.) and the Natural Sciences and Engineering Research Council of Canada for their support
0 Verlog Chemie. GmbH. 6940 Weinheim, 19x1
4 000 Hz
Fig. 2. A) 'H-NMR spectrum of the ybutyrolactone intercalate of hectorite at 80
MHz (I5 pulses). B) "C-NMR spectrum of the same intercalate recorded at 20
MHz (16000 pulses).
$ 02.50/0
Angew. Chem. Inr. Ed. Engl. 20 (1981) No. 1
two proton peaks for the xylene intercalate have relative intensities of 2: 3 and the chemical shifts are very similar to the
aromatic and methyl resonances in the high-resolution solution spectrum. The ”C-NMR spectrum shows separate sharp
absorptions for each of the three different types of carbon in
the molecule (linewidth ca. 25 Hz); and the relative chemical
shifts IS = 0.0
- 114.0 @ and - 108.5 @] are identical to
those of the pure liquid, again indicating that the molecules
are motionally relatively free. The I3C-NMR spectrum of ybutyrolactone (Fig. 2) shows four distinct peaks; and good
quality, readily interpretable, NMR spectra are obtained
from hectorite intercalates of several other organic molecules
including tetrahydrofuran, ethylbenzene and 1,3-pentanedione.
The composition of ethylbenzene/p-xylene mixed intercalates could readily be deduced from the ”C-NMR spectra of
the powdered solid. Moreover, the keto-enol equilibrium of
1,3-pentanedione in the interlamellar space is seen, by in situ
NMR measurement, to be displaced in favor of the enol
It proved readily possible with these systems to measure,
by standard methods, I3C spin-lattice relaxation times. For
the p-xylene intercalate the values are: @ 490, @430 and
C3 480 ms, essentially indistinguishable from one another
within the accuracy of the experiment. (Compare the corresponding values of 11.8,13.5, and 44.7 s for the purep-xylene
as liquid.) These differences again point to the integration of
the xylene guest into the sheet-silicate host. We have also
shown, and shall describe more fully elsewhere, that magicangle spinning, as expectedl8’, enhances the resolution of
both the proton and the carbon spectra of these intercalates.
Received: June 25. 1980 [ Z 664 IE]
German version: Angew. Chem. 93, 104 (1981)
[ I ] a ) A. Weiss in G. Eglingron. M. T. J. Murphy: Organic Geochemistry. Springer, Berlin 1969; h) R. M. Barrer in L. Mandelcorn: Non-Stoichiometric Compounds. Academic Press, New York 1964, p. 309; c) B. K. G. Theng: The
Chemistry of Clay-Organic Reactions Adam Hilger. London 1974. J. M.
Thumas in: Intercalation Chemistry (ed. A J. Jackson and M. S. Whirtingham). Academic Press, New York 1981 (in press).
121 a) J M. Thomas, J. M. Adams, S. H. Graham, D. T. B. Tennakoon. Adv.
Chem. Ser. 163, 298 (1977); b) D. T. B. Tennakoon, J. M Thomas, M. J.
Tricker. S. H. Graham, 1. Chem. SOC.Chem. Commun. 1974, 124: c) J . M.
Adams, S. H. Graham, P. I . Reid, J. M. Thomas, ibid. 1977, 67.
131 T. J. PinnaL,aia. P. K. Welrr, J. Am. Chem. Soc. 97, 3819 (1975).
(41 a) J M . Adams, J . A . Ballanrine, S. H. Graham, R. J Laub, J. H. Purnell, P I.
Reid. W Y M. Shaman, J. M. Thomas, Angew Chem. 90. 290 (1978); Angew. Chem. Int. Ed. Engl. 17. 282 (1978); J. Catal. 58. 238 (1979); c) J. M.
Thomas. Pure Appl Chem. 51, 1065 (1979).
[S] a) R. fuuillaux, P. Salvador, C. Vandermeersche, J J. Fripiar. Isr. J . Chem. 6,
337 (1968): b) A. M. Hechr, E. Geisder, J. Colloid Interface Sci. 34, 32 (1970):
c) J. J. friprar. ibid. 58, 51 1 (1977).
161 a) A . G. Whitney, I D. Gay, J. Calal. 25. 176 (1972); b) J. P. McTague, J.
Chem. Phys 50, 47 (1969).
171 a) J. M Adams. J. M. Thomas. M. J. Walrers, J Chem. SOC.Dalton Trans.
1975. 1459 b) J. M Adams, S. E. Davies. S. H. Graham, J. M. Thomas, J.
Chem SOC.Chem. Commun. 1978, 930; 1979, 527.
(81 J. R. LverIa. C. A. Fyfe, C. S. Yannoni. J . Am. Chem. SOC. !Of, 1351
Selective 7-Glycosylation of 4-Amino-7H-pyrrolo[2,3djpyrimidine to Ara-Tubercidin and Its a-Anomer
By Frank Seela and Heinz-Dieter Winkeler[‘’
4-Amino-7-(~-~-arabinofuranosyl)pyrrolo[2,3-dJpyrimidine (ara-tubercidin) (4b), like its aza analogue ara A[‘],has
Prof. Dr. F. Seela. Dipl.-Chem. H . - 0 . Winkeler
Universita! Paderborn-Gesamthochschule
Fachbereich I3 (Organische Chemie)
Warburger Str. 100. D-4790 Paderborn (Germany)
Angew Chem In1 Ed Engl 20 (1981) No. I
antiviral properties; however, it is not deaminated by adenosine deaminasel21and is therefore not deactivated.
Whereas ribonucleosides are only biologically accepted as
0-anomers, the a-anomers of arabinonucleosides are also of
interest since their 2’-hydroxy group is trans to the nucleobase and therefore several enzymes recognize a-o-arabinonucleosides like P-~-ribonucleosides~’~.
Ara-tubercidin (4b) can be obtained either semisynthetically from tubercidinf4]or by total synthesis via glycosylation
of 4-chloro-2-methylthio-7H-pyrrolo[2,3-dJpyrimidine’2’.
selective 7-glycosylation of the aglycone (1) has hitherto not
been described, since an exclusive activation of the pyrrole
nitrogen avoiding the N-glycosylation of the pyrimidine nitrogens was not possible.
We were able to couple (l)[2.5]with the halogenose (2)Ih1
selectively at N-7 without protecting the 4-amino group under the conditions of phase-transfer cataly~isl’~.A 1 : 1 mixture (‘H-NMR) of the anomers (3a) and (4a) is obtained in
57% yield, which, however, is difficult to separate on a preparative scale. Debenzylation of the mixture is accomplished
by hydrogenation in the presence of palladium on charcoal
and the reaction product is separated on an ionexchange column[’] yielding ara-tubercidin (4b)f2.41
and its a-anomer
2,3,5-Tri-0-benzyl-I -0-p-nitrobenzoyl-D-arabinofuranose[61(2.55 g , 4.4 mmol) is converted into the yellowish, viscous halogenose according to the procedure given in Ref.
(2). A suspension of pulverized (1) (0.5 g , 3.7
dichloromethane (10 cm’) and dimethoxyethane (5 cm3) is
stirred with benzyltriethylammonium chloride (0.15 g , 0.55
mmol) and 50% aqueous NaOH (15 cm’) for 5 min in a vibromixer.-The halo sugar is added dropwise to the emulsion and mixing of the layers is continued for a further 30
min. The organic layer is separated off, extracted with water,
dried over sodium sulfate, filtered, and evaporated. The oily
residue is dissolved in a small amount of chloroform/methano1 (99: 1) and chromatographed in the same solvent on silica gel (Lobar pre-packed column, size C, Merck). The main
zone is separated and the solvent removed; 1.12 g (57%) of a
yellowish, viscous mixture of the anomers (3a) and (4a) (1 : 1)
is obtained. TLC (CHC13/CH30H 98:2): Rc=0.3; UV
(CH’OH): A,, = 270 nm (E = 11400).
The mixture (3a)/(4a)(1.0 g , 1.9 mmol) dissolved in rnethanol (100 cm’) is hydrogenated at room temperature under
normal pressure with 10%palladium on charcoal as catalyst.
After filtration of the catalyst and evaporation of the solvent
a colorless, oily crude product is obtained which is applied
on a 2.5 x 30 cm ion-exchange column (Dowex 1 x 2, OH
0 Verlag Chemre. GmbH. 6940 Weinheim, 1981
$ 02 50/0
Без категории
Размер файла
241 Кб
compounds, intercalation, organiz, molecules, system, xylene, investigation, spectroscopy, nmr, sheet, hectorite, related, silicates
Пожаловаться на содержимое документа