摘要:

Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) -Ferrocenylvinylacetylenes Elena I. Klimova,*a Marcos Martinez Garcia,b Tatiana Klimova,a Lena Ruiz Ramireza and Jose Manuel Mendez Stivaleta a Department of Chemistry, National Autonomous University of Mexico, CP 04510 Mexico DF, Mexico. Fax: +5 25 622 5366; e-mail: klimova@servidor.unam.mx b Institute of Chemistry, National Autonomous University of Mexico, CP 04510 Mexico DF, Mexico.Fax: +525 616 2203 Thermolysis of 3-isopropyl- and 3-cyclobutyl-3-ferrocenylcyclopropenes results in the formation of 3-alkylidene-3-ferrocenylpropynes and (Z,E)-1-alkyl-1-ferrocenylpropenes; 2,2-dibromo-1-methyl-, 2,2-dibromo-1-isopropyl- and 2,2-dibromo-1-cyclobutylferrocenylcyclopropanes are converted into ferrocenylvinylacetylenes on treatment with ButOK in THF.It is well known that the introduction of a ferrocenyl substituent into a cyclopropane or cyclopropene ring substantially alters its properties. The transformations of gem-dihalo(ferrocenyl)cyclopropanes into 1,2- and 1,3-dienes under the action of BuLi or Na2CO3 in ethanol1–3 and of 2,2-dibromo-1-alkyl-1-ferrocenylcyclopropanes into monobromides, cyclopropenes and retrocyclization products upon treatment with ButOK in DMSO are the examples.4 3-Aryl-3-ferrocenylcyclopropanes easily undergo intramolecular transformations with small-ring opening followed by retrocyclization involving the aryl fragment.5–8 The reaction of 3-ferrocenyl-3-methylcyclopropene 1a with 1,3-diphenylisobenzofuran (DPIBF) also proceeds in an unusual way, the main product being compound 2, viz., an adduct of DPIBF with 3-ferrocenylbut-3-ene-1-yne 3a formed upon small-ring opening under reaction conditions, as depicted in the scheme.9 All attempts to identify 3-ferrocenylbut-3-ene-1-yne 3a under conditions of cyclopropene 1a thermolysis (refluxing in dry benzene, toluene or xylene in an inert atmosphere), without DPIBF or any other trap for expected 3a were unsuccessful.The only product isolated from the reaction mixture was 2-ferrocenylbut- 2-ene 5a, supposedly, as the trans-isomer. In addition, some other polymeric products of unknown structures were isolated. There are only two reports available in the literature concerning the synthesis of a-ferrocenyl-substituted vinylacetylenes, namely, 3-ferrocenyl-3-cyclohexylidenepropyne.1,3 This compound was synthesised by prolonged refluxing of 1,1-dibromo- 2-cyclohexyl-2-ferrocenylcyclopropane in ethanol (18% yield) or acetonitrile (48% yield) in the presence of Na2CO3.The absence of other data on the chemical properties of ferrocenylenynes and on convenient methods of their synthesis indicates that this class of compounds has not been adequately studied. On the other hand, these compounds can be used for the synthesis of ferrocene derivatives and for studies of the influence of a bulky ferrocenyl substituent on the reactions of conjugated enynes.We examined the preparation of this compounds by thermolysis of 3-alkyl-3-ferrocenylcyclopropenes with secondary alkyl substituents [alkyl = isopropyl (1b) or cyclobutyl (1c)].† We found that these compounds, in contrast to 3-ferrocenyl-3-methylcyclopropene 1a, afford 3-alkylidene-3-ferrocenylpropynes (3b,c)‡ and (Z,E)-1-alkyl-1-ferrocenylprop-1-enes (5b,c)§ as the main products on refluxing in benzene, together with small amounts of methyl vinyl ketones (6b,c),¶,†† respectively.The structures of the compounds obtained were established on the basis of the 1H and 13C NMR spectra and elemental analysis data.Thermolysis of cyclopropenes 1b,c in the presence of DPIBF†† leads to the formation of Diels–Alder adducts 7b,c and compounds 3b,c, 4, 5b,c and 6b,c. The Diels–Alder adducts were obtained as mixtures of two structural isomers 7b1 and 7b2 or 7c1 and 7c2 (~3:1),‡‡ as was found by 1H NMR spectroscopy.The X-ray analysis of the major isomers formed indicates that their structures correspond to exo-1,5-diphenyl-3-anti-ferrocenyl- 3-syn-isopropyl(or cyclobutyl)-6,7-benzo-8-oxatricyclo[3.2.1.02,4]- oct-6-enes (7b1,c1). The structures of minor isomers have not been established as yet. It is quite obvious that in this case heterolysis of a C–C bond of the cyclopropane ring leads to carbenoids 8b,c.We believe † gem-Dibromocyclopropanes 9b,c and cyclopropenes 1b,c were synthesised according to the published procedures.4,7–9 1b: yield 61%, orange crystals, mp 62–63 °C. 1H NMR (hereinafter, CDCl3) d: 0.79 (d, 6H, Me, J 6.73 Hz), 2.41 (m, 1H, CH, J 6.73 Hz), 4.12 (s, 5H, C5H5), 4.02 (s, 4H, C5H4), 6.95 (s, 2H, CH=). 13C NMR (hereinafter, CDCl3) d: 20.70 (Me), 29.91 (CH), 34.90 (C), 66.95 (C5H4), 68.01 (C5H5), 98.73 (CipsoFc), 110.59 (CH=).Found (%): C, 72.29; H, 7.03; Fe, 21.08. Calc. for C16H18Fe (%): C, 72.21; H, 6.81; Fe, 20.98. 1c: yield 52%, orange crystals, mp 66°C. 1H NMR, d: 1.60–2.25 (m, 6H, CH2), 2.85 (m, 1H, CH), 4.11 (s, 5H, C5H5), 3.97 (m, 2H, C5H4), 4.02 (m, 2H, C5H4), 7.05 (d, 2H, CH=, J 0.8 Hz). 13C NMR, d: 14.67, 16.97 (CH2), 29.99 (CH), 33.98 (C), 66.91 (C5H4), 68.00 (C5H5), 98.65 (CipsoFc), 109.93 (CH=).Found (%): C, 73.56; H, 6.38; Fe, 20.14. Calc. for C17H18Fe (%): C, 73.40; H, 6.52; Fe, 20.08. ‡ 3a: yield 52%, orange oil. 1H NMR, d: 3.01 (s, 1H, CH=), 4.16 (s, 5H, C5H5), 4.24 (m, 2H, C5H4), 4.51 (m, 2H, C5H4), 5.47 (d, 1H, CH2, J 0.9 Hz), 5.60 (d, 1H, CH2, J 0.9 Hz). 13C NMR, d: 66.67, 69.09 (C5H4), 69.65 (C5H5), 76.51 (CH=), 82.93 (CipsoFc), 89.97 (C=), 118.15 (CH2=), 128.42 (C).Found (%): C, 71.33; H, 4.99; Fe, 23.54. Calc. for C14H12Fe (%): C, 71.22; H, 5.12; Fe, 23.66. 3b: yield 61%, orange oil. 1H NMR, d: 1.85 (s, 3H, Me), 2.02 (s, 3H, Me), 2.89 (s, 1H, CHº), 4.12 (s, 5H, C5H5), 4.15 (m, 2H, C5H4), 4.19 (m, 2H, C5H4). Found (%): C, 72.87; H, 6.03; Fe, 21.19.Calc. for C16H16Fe (%): C, 72.75; H, 6.11; Fe, 21.14. 3c: yield 53%, orange oil. 1H NMR, d: 1.81–2.53 (m, 6H, CH2), 3.01 (s, 1H, CHº), 4.14 (s, 5H, C5H5), 4.18 (m, 2H, C5H4), 4.29 (m, 2H, C5H4). Found (%): C, 73.85; H, 6.05; Fe, 20.07. Calc. for C17H16Fe (%): C, 73.93; H, 5.84; Fe, 20.23. a Me Fc Fc H H H H H 1a C C CH H2C Fc DPIBF 3a O Ph Ph 4 DPIBF Ph Ph O C Fc CH 2 Fc = C5H5FeC5H4 C C Me Fc H Me 1a D + polymers 5aMendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) that compounds 3b,c and 5b,c result from disproportionation of carbenoids 8b,c according to the following scheme: Methyl vinyl ketones 6b,c are formed upon hydration of acetylenes 3b,c during chromatographic separation of the reaction mixtures. The fact that 1,3-dihydro-1,3-diphenylisobenzofuran 4 is formed during the thermolysis of cyclopropenes 1a9 and 1b,c in the presence of DPIBF indicates that 1,3-diphenylisobenzofuran can act as a partner in the disproportionation of carbenoids 8a–c § 5a: yield 28%, orange oil. 1H NMR, d: 1.44 (d, 3H, Me, J 6.67 Hz), 1.78 (s, 3H, Me), 4.06 (s, 5H, C5H5), 4.01 (m, 2H, C5H4), 4.23 (m, 2H, C5H4), 5.52 (q, 1H, CH=, J 6.67 Hz).Found (%): C, 69.87; H, 6.93; Fe, 23.41. Calc. for C14H16Fe (%): C, 70.02; H, 6.72; Fe, 23.26. (Z,E)-5b (2:1), Rf = 0.75 (hexane), yield 30.5%, orange oil. 1H NMR for (Z)-5b, d: 1.17 (d, 6H, Me, J 6.8 Hz), 1.81 (d, 3H, Me, J 6.6 Hz), 2.40 (m, 1H, CH, J 6.8 Hz), 4.05 (s, 5H, C5H5), 4.00 (m, 1H, C5H4), 4.20 (m, 2H, C5H4), 4.27 (m, 1H, C5H4), 5.51 (q, 1H, CH=, J 6.6 Hz); for (E)-5b, d: 1.19 (d, 6H, Me, J 6.75 Hz), 1.70 (d, 3H, Me, J 6.62 Hz), 2.75 (m, 1H, CH, J 6.75 Hz), 4.03 (s, 5H, C5H5), 3.75 (m, 1H, C5H4), 4.02 (m, 1H, C5H4), 4.18 (m, 1H, C5H4), 4.43 (m, 1H, C5H4), 5.83 (q, 1H, CH=, J 6.62 Hz).Found for (Z,E)-5b (%): C, 71.52; H, 7.65; Fe, 20.98. Calc. for C16H20Fe (%): C, 71.66; H, 7.51; Fe, 20.83. (Z,E)-5c (2.5:1), Rf = 0.71 (hexane), yield 28.1%, orange oil. 1H NMR for (Z)-5c, d: 1.48 (d, 3H, Me, J 6.8 Hz), 1.63–2.40 (m, 6H, CH2), 2.85 (m, 1H, CH), 4.12 (s, 5H, C5H5), 4.02 (m, 2H, C5H4), 4.16 (m, 2H, C5H4), 5.84 (q, 1H, CH=, J 6.8 Hz); for (E)-5c, d: 1.76 (d, 3H, Me, J 7.3 Hz), 1.82–2.40 (m, 6H, CH2), 2.55 (m, 1H, CH), 4.15 (s, 5H, C5H5), 3.86 (m, 2H, C5H4), 4.07 (m, 2H, C5H4), 5.50 (q, 1H, CH=, J 7.3 Hz). Found for (Z,E)-5c, (%): C, 72.74; H, 7.27; Fe, 20.06. Calc.for C17H20Fe (%): C, 72.87; H, 7.19; Fe, 19.94. ¶ 6a: yield 8%, violet crystals, mp 67–68 °C. 1H NMR, d: 1.98 (s, 3H, Me), 4.18 (s, 5H, C5H5), 4.25 (m, 2H, C5H4), 4.47 (m, 2H, C5H4), 5.71 (s, 1H, CH2), 5.89 (s, 1H, CH2). Found (%): C, 66.24; H, 5.32; Fe, 22.04. Calc. for C14H14FeO (%): C, 66.17; H, 5.55; Fe, 21.98. 6b: yield 15%, violet crystals, mp 71–72 °C. 1H NMR, d: 1.74 (s, 3H, Me), 1.96 (s, 3H, Me), 2.05 (s, 3H, Me), 4.23 (s, 5H, C5H5), 4.32 (m, 2H, C5H4), 4.54 (m, 2H, C5H4). Found (%): C, 68.29; H, 6.27; Fe, 19.93. Calc. for C16H18FeO (%): C, 68.11; H, 6.43; Fe, 19.7. 6c: yield 12%, violet crystals, mp 74–75 °C. 1H NMR, d: 1.93 (s, 3H, Me), 1.98–2.68 (m, 6H, CH2), 4.21 (s, 5H, C5H5), 4.31 (m, 2H, C5H4), 4.46 (m, 2H, C5H4).Found (%): C, 69.66; H, 6.04; Fe, 18.78. Calc. for C17H18FeO (%): C, 69.41; H, 6.20; Fe, 19.00. †† Synthesis of 3-alkylidene-3-ferrocenylpropynes 3a–c. gem-Dibromoferrocenylcyclopropanes 9a–c (2 mmol) were added to a solution of ButOK (0.56 g, 5 mmol) in dry THF (50 ml) with stirring under dry argon at 5–10 °C. Stirring was continued for 2–3 h at room temperature, and then water (50 ml) was added.The organic layer was separated, dried with CaCl2 and concentrated. The residue was chromatographed on a plate with neutral alumina (Brockmann activity III) in hexane. Thermolysis of 3-alkyl-3-ferrocenylcyclopropenes 1a–c. A solution of 1 mmol of cyclopropenes 1a–c in 50 ml of dry benzene was boiled for 3–5 h until the disappearance of the initial cyclopropenes (TLC, hexane).Following the removal of the solvent, the residue was subjected to preparative TLC on silica gel (hexane). Reaction of cyclopropenes 1b,c with 1,3-diphenylisobenzofuran. A solution of 0.56 g (2 mmol) of DPIBF and of 0.41 g (1.5 mmol) of cyclopropenes 1b,c in 60 ml of dry benzene was refluxed for 5 h (monitoring by TLC on silica gel, as in the previous experiment).Then, the solvent was removed, and TLC on SiO2 (hexane–benzene, 2:1) was carried out. The following compounds were separated: 1,3-dihydro-1,3- diphenylisobenzofuran 4,9 alkenes 5b,c, propynes 3b,c, vinyl ketones 6b,c and Diels–Alder adducts 7b,c (mixture of isomers, 3 :1). Reaction of propyne 3a with 1,3-diphenylisobenzofuran. A mixture of 3-ferrocenylbut-3-ene-1-yne 3a (0.24 g, 1 mmol) and 1,3-isobenzofuran (0.27 g, 1 mmol) in 50 ml of dry benzene was stirred at room temperature for 10 h.Then, the solvent was removed in a vacuum, and TLC on SiO2 (hexane–benzene, 2:1) was carried out. The following compounds were separated: endo-2a, Rf = 0.27, yield 46%, mp 205 °C; exo-2b, Rf = 0.32, yield 22%, mp 195–196 °C.9 and in the generation of enynes 3a–c. Further, we have found that ButOK in THF, unlike ButOK in DMSO,4,10,11 is a convenient reagent1 for the preparation of ferrocenylvinylacetylenes from corresponding gem-dibromocyclopropanes 9a–c,§§ the yields of acetylenes 3a–c can be as high as 52–63%.†† However, the formation of methyl vinyl ketones 6a–c (8–15%) during isolation and purification cannot be avoided: The reaction seems to occur via intermediate 3-alkyl-1- bromo-3-ferrocenylcyclopropenes 10a–c, although these cannot be captured when the reaction was carried out in the presence of 1,3-dienes.‡‡ 7b1: Rf = 0.29 (hexane–benzene, 2:1), yield 34%, yellow crystals, mp 226–227 °C. 1H NMR, d: 0.39 (d, 6H, Me, J 6.68 Hz), 2.45 (s, 2H, CH), 2.95 (m, 1H, CH, J 6.68 Hz), 4.07 (s, 5H, C5H5), 3.91 (s, 4H, C5H4), 6.95–7.83 (m, 14H, 3Ar).Found (%): C, 80.42; H, 5.94; Fe, 10.54. Calc. for C36H32FeO (%): C, 80.60; H, 6.01; Fe, 10.41. 7b2: Rf = 0.19 (hexane–benzene, 2:1), yield 10%, yellow crystals, mp 234–235 °C. 1H NMR, d: 0.42 (d, 6H, Me, J 6.7 Hz), 2.40 (s, 2H, CH), 2.72 (m, 1H, CH, J 6.7 Hz), 3.97 (s, 5H, C5H5), 4.11 (s, 4H, C5H4), 7.05–7.81 (m, 14H, 3Ar). Found (%): C, 80.76; H, 6.24; Fe, 10.18. Calc.for C36H32FeO (%): C, 80.60; H, 6.01; Fe, 10.41. 7c1: Rf = 0.32 (hexane–benzene, 2:1), yield 36%, yellow crystals, mp 218–219 °C. 1HNMR, d: 1.42–2.05 (m, 6H, CH2), 2.41 (s, 2H, CH), 2.92 (m, 1H, CH), 4.05 (s, 5H, C5H5), 4.01 (s, 4H, C5H4), 7.00–7.91 (m, 14H, 3Ar). Found (%): C, 80.93; H, 5.65; Fe, 10.23. Calc. for C37H32FeO (%): C, 81.02; H, 5.88; Fe, 10.18. 7c2: Rf = 0.32 (hexane–benzene, 2:1), yield 11%, yellow crystals, mp 231–232 °C. 1H NMR, d: 1.75–2.35 (m, 6H, CH2), 2.46 (s, 2H, CH), 3.15 (m, 1H, CH), 4.08 (s, 5H, C5H5), 3.94 (m, 2H, C5H4), 4.04 (m, 2H, C5H4), 7.15–7.76 (m, 14H, 3Ar). Found (%): C, 81.14; H, 5.92; Fe, 10.19. Calc. for C37H32FeO (%): C, 81.02; H, 5.88; Fe, 10.18. §§ 9b: yield 74%, orange crystals, mp 123–124 °C. 1H NMR, d: 0.98 (d, 3H, Me, J 6.8 Hz), 1.15 (d, 3H, Me, J 6.8 Hz), 1.75 (d, 1H, CH2, J 7.2 Hz), 2.11 (d, 1H, CH2, J 7.2 Hz), 2.17 (m, 1H, CH), 4.16 (s, 5H, C5H5), 4.21 (m, 2H, C5H4), 4.25 (m, 2H, C5H4).Found (%): C, 44.85; H, 4.34; Fe, 13.70; Br, 37.63. Calc. for C16H18Br2Fe (%): C, 45.09; H, 4.26; Fe, 13.10; Br, 37.55. 9c: yield 72%, orange crystals, mp 127–128 °C. 1H NMR, d: 1.56 (s, 1H, CH2), 1.87 (s, 1H, CH2), 1.70–2.55 (m, 6H, CH2), 2.58 (m, 1H, CH), 4.15 (s, 5H, C5H5), 3.46 (m, 1H, C5H4), 4.03 (m, 1H, C5H4), 4.13 (m, 1H, C5H4), 4.21 (m, 1H, C5H4).Found (%): C, 46.71; H, 4.28; Fe, 12.52; Br, 36.63. Calc. for C17H18Br2Fe (%): C, 46.60; H, 4.14; Fe, 12.74; Br, 36.52. 2[1b,c] D H H Fc C R H R CHR2 Fc H 8b,c 3b,c + 5b,c C Fc H R R 1b,c CH Fc R R Ph Ph O Fc C C C R R CH C C H R R Fc C Me H Fc C C C R R Me O D D DPIBF 7b,c 48% 3b,c 16% 4 7% 5b,c 8% 6b,c 3–6% 3b,c 23% 5b,c 30% 6b,c 5% b R = Me c R + R = (CH2)3 Fc C Br Br R H R 9a–c Fc C Br R H R 10a–c ButOK THF 3a–c + 6a–c a R = H b R = Me c R + R = (CH2)3Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Further, we have found that 3-ferrocenyl-4-methylpent-3- en-1-yne 3b and 3-cyclobutylidene-3-ferrocenylpropyne 3c, respectively, do not react with DPIBF even on refluxing in m-xylene. This is in contrast to the behaviour of 3-ferrocenylbut- 3-en-1-yne 3a,‡ which gave a Diels–Alder adduct as a mixture of endo- and exo-isomers (2a:2b ~ 2:1) in an almost quantitative yield.9 a-Ferrocenylvinylacetylenes 3a–c readily add water upon dissolution in wet solvents and upon chromatographing on alumina (Brockmann activity III).When stored under ordinary conditions, they undergo rapid polymerization and resinification. References 1 W. M. Horspool, R. G. Sutherland and B. J. Thomson, J. Chem. Soc. (C), 1971, 1554. 2 W. M. Horspool, R. G. Sutherland and B. J. Thomson, J. Chem. Soc. (C), 1971, 1558. 3 W. M. Horspool, R. G. Sutherland and B. J. Thomson, J. Chem. Soc. (C), 1971, 1563. 4 E. I. Klimova, N. N. Meleshonkova, T. B. Klimova, M. G. Martinez and C. T. Alvarez, Mendeleev Commun., 1997, 242. 5 A. J. Fray, P. S. Jain and R. L. Krieger, J. Organomet. Chem., 1981, 214, 381. 6 A. J. Fray, R. L. Krieger, I. Agranat and E. Aharon-Shalom, Tetrahedron Lett., 1976, 32, 4803. 7 E. I. Klimova, T. B. Klimova, L. Ruiz Ramirez, M. G. Martinez, C. T. Alvarez, P. G. Espinova and A R. Toscano, J. Organomet. Chem., 1997, 545, 191. 8 E. I. Klimova, M. G. Martinez, T. B. Klimova, C. T. Alvarez, Ar R. Toscano, R. Moreno Esparza and L. Ruiz Ramirez, J. Organomet. Chem., 1998, 566, 175. 9 E. I. Klimova, L. Ruiz Ramirez, T. B. Klimova, M. G. Martinez, N. N. Meleshonkova and A. V. Churakov, J. Organomet. Chem., 1998, 559, 1. 10 T. C. Shields and W. E. Billups, Chem. Ind., 1967, 25, 1999. 11 T. C. Shields, W. E. Billups and A. N. Kurtz, Angew. Chem., Int. Ed. Engl., 1968, 7, 209. Received: 2nd June 1999; Com. 99/1509

ISSN:0959-9436     

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Cyclic (4S)-chloromethyl sulfite and sulfate derivatives of (S)-glycidol as valuable synthetic equivalents of scalemic epichlorohydrin Alexander A. Bredikhin,* Sergey N. Lazarev, Alexander V. Pashagin and Zemfira A. Bredikhina A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Centre of the Russian Academy of Sciences, 420088 Kazan, Russian Federation.Fax: +7 8432 75 2253; e-mail: baa@iopc.kcn.ru The interaction of (S)-glycidol with SOCl2 or SO2Cl2 in stoichiometric amounts leads to the formation of cyclic (4S)-chloromethyl sulfite or sulfate derivatives with the same enantiomeric purity; based on this reaction, a new procedure for the synthesis of (S)-propranolol was developed. 1-Chloro-2,3-epoxypropane (epichlorohydrin) 1 is one of the epoxy compounds most frequently used in organic synthesis.In particular, racemic epichlorohydrin is a key starting material in commercial processes for the production of b-adrenoreceptor blockers 2,1 valuable cardiovascular drugs: The formation of products of double nucleophilic displacement, (ArOCH2)2CH(OH), which usually accompanies the main reaction,2 is a minor limitation for the use of 1 in the above and related processes.Some other weak points of epichlorohydrinbased synthetic strategies may appear on going from racemic to scalemic b-blockers as target products. Thus, scalemic 1 is an expensive and not easily available substance.3 On the other hand, the nucleophilic displacement of a chlorine atom in 1 may be accompanied by the Payne-type rearrangement, which is well known for analogous processes in glycidyl tosilates4 and causes partial racemization of the final products.It is hoped that the use of 4-chloromethyl-2-oxo- and 4-chloromethyl-2,2-dioxo-1,3,2-dioxathiolanes 3 and 4 as synthetic equivalents of epichlorohydrin can allow us to avoid the disadvantages of compound 1.For example, racemic 4 was successfully used in the synthesis of a key intermediate for preparing the racemic b-blocker acebutolol [2a, Ar = 2-(MeCO)- 4-(PrCONH)C6H3, R = But].2 In all published procedures for the synthesis of rac-32,5–7 and rac-4,2,8 rac-15 or rac-3-chloropropane-1,2-diol2,6–8 was used as the starting material, and no scalemic 3 and 4 were mentioned in the literature.Here, we report an efficient new way to cyclic chloromethyl-substituted sulfites and sulfates starting from 2,3- epoxypropan-1-ol (glycidol) 5. Note that at present scalemic glycidol is one of the easily accessible chiral C3 synthons. We found that the reaction of 1 equiv. of rac-5 with 0.5 equiv. of SOCl2 in the presence of 1.1 equiv. of NEt3 results in trivial diglycidyl sulfite 6 formed as a mixture of three diastereomers (two achiral meso- and racemic chiral isomers approximately in the 1:1:2 ratio).† However, along with main product 6, up to 20% of cyclic chloromethyl sulfite 3 (two diastereomers in the cis:trans ratio 41:59) was isolated and identified.Cyclic sulfites 3 became major products (isolated yield up to 90%) when the reaction of equimolar amounts of glycidol and SOCl2 took place in the presence of 1 equiv.of a tertiary amine or without any base. Cyclic sulfites 3 in a scalemic form were obtained in the same yield when the reaction of (S)-glycidol (ee = 90.0%;‡ obtained by Sharpless asymmetric epoxydation9 of allyl alcohol) and SOCl2 took place under analogous conditions. The scalemic diastereomers of 3 were separated by column chromatography.§ † 6: bp 145–147 °C/1 mmHg. 1H NMR (250 MHz, CDCl3) d: 4.17–4.05 and 3.70–3.55 (m, OCH2), 3.04–2.96 (m, CH), 2.64–2.60 and 2.47–2.43 (m, CH2-oxirane). 13C NMR (100.6 MHz, CDCl3) d: 62.63, 62.44, 62.34 (OCH2), 48.95, 48.94, 48.91 (CH), 43.87, 43.82, 43.80 (CH2-oxirane). ‡ The enantiomeric composition was determined by GLC on a Biochrom-1 chromatograph using a Supelco b-Dex-120 column (30 m×0.25 mm).It is well known that a diastereomer of rac-3 with a longer retention time exhibits the trans structure.7 Unfortunately, owing to the similarity of the retention times for two enantiomers we failed to determine the enantiomeric purity for cis-3. The enantiomeric purity measured for the trans isomer (ee = 89.3%) was practically equal to that of parent glycidol.Based on this fact, the (2R,4S)-configuration was easily attributed to the trans isomer and the (2S,4S)-configuration, to the other. When glycidol was mixed with SO2Cl2 under the above conditions, a viscous sulfur-containing mixture was the main reaction product. Better results were obtained by mixing solutions of SO2Cl2 and (S)-5 in CH2Cl2 without any base at –90 °C.About 50% of cyclic sulfate (S)-4 was isolated from the reaction mixture by distillation. The same product¶ can be obtained in 35% yield by oxidation of a mixture of isomeric (4S)-3 with aqueous KMnO4 in a two-phase system. The total yields of target sulfate 4 prepared by direct sulfurization of 5 with SO2Cl2 or by a two-step procedure starting from SOCl2 are comparable; however, the latter procedure gives the product of higher purity.†† The yield in the two-step procedure can be considerably improved with the use of the standard RuCl3–NaIO4 oxidising system.11,12 § Silica gel, light petroleum–diethyl ether.(2S,4S)-3: Rf = 0.31 (light petroleum –diethyl ether, 8:5), [a]D 20 = –6.3 (c 0.64, CH2Cl2). 1H NMR (250 MHz, CDCl3) d: 4.78–4.68 (m, 1H, OCH), 4.58–4.43 (m, 2H, OCH2), 3.81 (d, 2H, CH2Cl, 3J 5.3 Hz). 13C NMR (100.6 MHz, CCl4 + C6D6) d: 80.93 (CH), 69.98 (OCH2), 43.35 (CH2Cl). (2R,4S)-3: Rf = 0.27 (light petroleum– diethyl ether, 8:5), [a]D 20 = 58.2 (c 0.3, CH2Cl2). 1H NMR (250 MHz, CDCl3) d: 5.14–5.04 (m, 1H, OCH), 4.66 (dd, 1H, OCH2, 3J 5.6 Hz, 2J 9.0 Hz), 4.32 (dd, 1H, OCH2, 3J 6.4 Hz, 2J 9.0 Hz), 3.62 (d, 2H, CH2Cl, 3J 5.4 Hz). 13C NMR (100.6 MHz, CCl4 + C6D6) d: 78.83 (CH), 68.94 (OCH2), 42.56 (CH2Cl). Lit. 13C NMR data for rac-3 see in ref. 10. ¶ (S)-4: bp 80–82 °C/0.05 mmHg; nD 20 = 1.4640; [a]D 20 = –2.1 (c 3.4, CH2Cl2). 1H NMR (250 MHz, CDCl3) d: 5.15 (approx. quint., 1H, CH), 4.85 (dd, 1H, OCH2, 3J 6.8 Hz, 2J 8.9 Hz), 4.65 (dd, 1H, OCH2, 3J 6.6 Hz, 2J 8.9 Hz), 3.84 (d, 2H, CH2Cl, 3J 5.8 Hz). 13C NMR (100.6 MHz, CDCl3) d: 79.50 (CH), 70.25 (OCH2), 41.46 (CH2Cl). O Cl ArOH + O OAr base ArO NHR OH H2NR 1 2 O CH2 O S OCH2 O O * * O OH O S O O CH2Cl 6 rac-5 3 0.5 equiv. SOCl2 1.1 equiv. NEt3 Et2 O, –70 °C~0 °C, CH2Cl2 1 equiv. SOCl21 equiv. NEt3 O S O O (2S,4S)-3 OH OH + SOCl2H CH2 Cl O S O O H ClH2 C (2R,4S)-3 (S)-5 ~0 °C, CH2 Cl2 1:11 2 3 4Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Cyclic sulfites and sulfates, which have been known for a long time, were considered as a minor and peripheral class of organic compounds until Gao and Sharpless11 have recognised them as being “like epoxides only more reactive”. Reviews on the chemistry of these substances were published,12 and the “cyclic sulfite/sulfate route” became a popular way to a diversity of bioactive products.(S)-Propranolol (2b, Ar = 1-naphthyl, R = Pri) was also synthesised from a mixture of diastereomeric (4R)-naphthyloxymethyl-2-oxo-1,3,2-dioxathiolanes (4R)-7, which †† The distilled sample of 4 obtained by the direct action of SO2Cl2 on glycidol contains 6–10% of the six-membered cyclic sulfate 5-chloro-2,2- dioxo-1,3,2-dioxathiane. 13C NMR (100.6 MHz, CDCl3) d: 76.38 (OCH2), 46.74 (CHCl).Only trace amounts of this impurity were detected in a sample of 4 obtained by the two-step procedure. The two pairs of signals of diastereomeric 5-chloro-2-oxo-1,3,2-dioxathianes [13CNMR (100.6MHz, CDCl3) d: 60.87 and 60.20 (OCH2), 46.92 and 51.64 (CHCl); cf. ref. 13] with the total integral intensity lower than 2% can also be found in the spectra of crude 3.were prepared from rather exotic (R)-3-benzyloxypropane-1,2- diol by a four-step procedure.14 In a preliminary run, we prepared (S)-2b‡‡ in three steps starting from (S)-glycidol with the overall yield of about 75%. We are grateful to Dr. V. P. Mukhina for her assistance in chromatographic measurements and to Dr. N. M. Azancheev for measuring NMR spectra.References 1 Pharmaceutical Manufacturing Encyclopedia, ed. M. Sittig, Noyes Publication, Park Ridge, 1988, vols. 1 and 2. 2 V. Massonneau, X. Radisson, M. Mulhauser, N. Michel, A. Buforn and B. Botannet, New J. Chem., 1992, 16, 107. 3 (a) N. Kasai, T. Suzuki and Y. Furukawa, J. Mol. Catal., B: Enzymatic, 1998, 4, 237; (b) J. J. Baldwin, A. W. Raab, K.Mensler, B. H. Arison and D. E. McClure, J. Org. Chem., 1978, 43, 4876; (c) Y. Kawakami, T. Asai, K. Umeyama and Y. Yamashita, J. Org. Chem., 1982, 47, 3581; (d) M. K. Ellis, B. T. Golding, A. B. Maude and W. P. Watson, J. Chem. Soc., Perkin Trans. 1, 1991, 747. 4 (a) G. B. Payne, J. Org. Chem., 1962, 27, 3819; (b) P. H. J. Carlsen and K. Aase, Acta Chem. Scand., 1994, 48, 273. 5 G. A. Razuvaev, V. S. Etlis and L. N. Grobov, Zh. Obshch. Khim., 1961, 31, 1328 [J. Gen. Chem. USSR (Engl. Transl.), 1961, 31, 1230]. 6 P. B. D. de la Mare, W. Klyne, D. J. Millen, J. G. Prichard and D.Watson, J. Chem. Soc., 1956, 1813. 7 C. H. Green and D. G. Hellier, J. Chem Soc., Perkin Trans. 2, 1975, 190. 8 K. P. M. Vanhessche and K. B. Sharpless, Chem. Eur. J., 1997, 3, 517. 9 R.A. Johnson and K. B. Sharpless, in Catalytic Asymmetric Synthesis, ed. I. Ojima, VCH, New York, 1993, p. 103. 10 G. W. Buchanan and D. G. Hellier, Can. J. Chem., 1976, 54, 1428. 11 Y. Gao and K. B. Sharpless, J. Am. Chem. Soc., 1988, 110, 7538. 12 (a) B. B. Lohray, Synthesis, 1992, 1035; (b) H. C. Kolb, M. S. van Nieuwenhze and K. B. Sharpless, Chem. Rev., 1994, 94, 2483; (c) B. B. Lohray and V. Bhushan, Adv. Heterocycl. Chem., 1997, 68, 89. 13 J.-P. Gorrichon, G. Chassaing and L. Cazaux, Org. Magn. Reson., 1983, 21, 426. 14 P. H. J. Carlsen and K. Aase, Acta Chem. Scand., 1993, 47, 737. 15 H. S. Bevinakatti and A. A. Banerji, J. Org. Chem., 1991, 56, 5372. ‡‡ (S)-2b·HCl: mp 185–187 °C, [a]D 25 = –22.6 (c 0.66, EtOH). Lit.,15 mp 194–196 °C, [a]D 25 = –25.5 (c 1.05, EtOH). O S O O O CH2Cl H (S)-5 + SO2Cl2 (4S)-3 1:1; –90 °C CH2Cl2 KMnO4/H+ CH2Cl2/H2O (S)-4 O H OH (S)-5 O S O CH2Cl O S O CH2O O HO H NHPri (4S)-3 (4R)-7 (S)-2b i ii iii O O Reagents and conditions: i, SOCl2, CH2Cl2, ~0 °C; ii, NaH, 1-naphthol, toluene; iii, PriNH2, DMF. Diastereomeric mixtures of 3 and 7 were used. Received: 9th July 1999; Com. 99/1518

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Trifluoroacetylation of O-vinyl acetoxime Boris A. Trofimov,* Elena Yu. Schmidt, Al’bina I. Mikhaleva, Alexander M. Vasil’tsov, Ludmila I. Larina and Ludmila V. Klyba Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk, Russian Federation. Fax: +7 3952 39 6046; e-mail: bat@irioch.irk.ru O-Vinyl acetoxime reacts with trifluoroacetic anhydride (pyridine, room temperature) to form (E)-O-[2-(trifluoroacetyl)vinyl] acetoxime or 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1,2-oxazole.Vinyl ethers,1 N-vinyl amides1 and vinyl sulfides2,3 are known to be capable of undergoing the non-typical (for ordinary alkenes) electrophilic substitution at the b-vinylic carbon when treated with trifluoroacetic or trichloroacetic anhydrides.Note that under similar conditions, N-vinylpyrroles are trifluoroacetylated normally at the a-position of the pyrrole ring retaining their N-vinyl group intact.4,5 Despite its extraordinary nature, synthetic and mechanistic importance, this type of vinylic electrophilic substitution still has not got the attention it deserves. This note is a preliminary communication on the trifluoroacetylation of currently available6,7 O-vinyl oximes, representing the first example of electrophilic substitution at the vinyl group adjacent to two directly linked heteroatoms, CH2=CHON, wherein the basic nitrogen can be concurrently attacked by an electrophile.We found that O-vinyl acetoxime 1 reacts readily with trifluoroacetic anhydride in the presence of pyridine at room temperature to give expected1–3 (E)-O-[2-(trifluoroacetyl)vinyl] acetoxime 2 after direct distillation in 53% yield (not optimised yield) along with pyridinium trifluoroacetate 3 and incompletely reacted pyridine–trifluoroacetic anhydride complex 4.However, when the reaction mixture is treated with aqueous NaHCO3, 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1,2-oxazole 5 is isolated as the only product in 65% yield (Scheme 1).The structure of oxazole 5 follows from the 1H, 13C, 19F and 15N NMR spectra as well as from the fragmentation under electron ionization.† The chemical shift of 15N (–6.41 ppm) corresponds to the 1,2-oxazole structure (–12.0 to 2.2 ppm).8,9 In the IR spectrum of a dilute solution of oxazole 5 in CCl4 (0.001 M), only a narrow symmetric band at 3577 cm–1 is present in the region 3000–3700 cm–1.This band can be attributed to the following intramolecular H-bond: The similar H-bonding was observed earlier10 in 2,6-difluorophenol (nOH = 3586 cm–1). The formation of 5 implies the hydrolysis of 2 via intermediate semi-acetal-like adduct 6 which decomposes to 3-oxo- 4,4,4-trifluorobutyraldehyde 7 and acetoxime 8.The two latter compounds undergo reoximation to result in corresponding aldoxime 9 and acetone (the hydroxylamine exchange between oximes and aldehydes or ketones under solvolytic conditions is a well-established fact11). The intramolecular hydroxyl–carbonyl interaction in aldoxime 9 leads to the ring closure with the formation of oxazole 5 (Scheme 2).Similar compounds, 5-amino-5-trifluoromethyl-3-substituted- 4,5-dihydro-1,2-oxazoles (D2-isoxazolines), have been recently synthesised by an entirely different reaction from 2-amino-2- trifluoromethyl-5,5-dimethyltetrahydro-4-pyrones and hydroxylamine. 12 Thus, the perfluoroacylation of O-vinyl oximes promises to become a source of highly reactive perfluoroalkyl-substituted ketoaldehydes and 1,2-oxazole derivatives, new potent building blocks for the design of biologically active molecules.While the trifluoroacetylation of O-vinyl oximes originates a novel class of multifunctional compounds, the cyclization of trifluoroacetyl acetaldoxime is a useful supplement to the wellknown syntheses12–14 of 4,5-dihydro-1,2-oxazoles (apart from † 1H NMR (400.13 MHz), 13C NMR (101.61 MHz) in CDCl3, standard TMS; 19F NMR (89.35 MHz) in CDCl3, standard CCl3F; 15N NMR (40.56 MHz) in [2H6]DMSO, standard MeNO2.To a mixture of 1.98 g (20 mmol) of O-vinyl acetoxime 1 and 1.58 g (20 mmol) of pyridine in 15 ml of diethyl ether, 4.2 g (20 mmol) of trifluoroacetic anhydride was added dropwise for 1.5 h. (a) Upon distillation of the reaction mixture in a vacuum, 2.07 g of oxime 2 (yield 53%) was isolated, bp 60–63 °C (2 mmHg). 1H NMR, d: 8.21 (d, H-2, 3J2–3 12.3 Hz), 6.18 (d, H-3, 3J2–3 12.3 Hz), 2.02, 2.00 (Me2). 13C NMR, d: 180.36 (C=O, 2JC–F 35.1 Hz), 166.91 (C-2), 163.89 (C-4), 116.53 (CF3, 1JC–F 290.6 Hz), 97.80 (C-3), 21.47, 16.73 (Me2). 19F NMR, d: –78.73. IR (neat, n/cm–1): 571, 536, 582, 595, 683, 700, 726, 752, 826, 898, 972, 1055, 1145, 1195, 1257, 1279, 1308, 1371, 1435, 1598, 1650, 1688, 1711, 1793, 2852, 2926, 2964, 3001, 3052, 3086.Found (%): C, 42.99; H, 4.56; N, 7.20; F, 28.67. Calc. for C7H8F3NO2 (%): C, 43.08; H, 4.13; N, 7.18; F, 29.21. (b) The reaction mixture was poured into 30 ml of a saturated aqueous NaHCO3 solution. The organic layer was separated, and the aqueous layer was extracted with diethyl ether (4×5 ml).The combined extract was washed with water (3×5 ml) and dried over MgSO4. After the removal of ether and vacuum sublimation (1 mmHg) of the residue, 2.01 g (65%) of oxazole 5 was obtained, mp 41–42 °C. 1H NMR, d: 7.30 (nr. m, H-3, 3J3–4 1.7 Hz, 3J3–4' 1.5 Hz, 5JH–F 0.8 Hz), 3.72 (br. s, OH), 3.37 (dq, H-4, 2J4–4' 18.8 Hz, 3J3–4 1.7 Hz, 4JH–F 0.5 Hz), 3.18 (dq, H-4', 2J4–4' 18.8 Hz, 3J3–4' 1.5 Hz, 4JH–F 1.5 Hz). 13C NMR, d: 146.58 (C-3, 1J3–4 34.8 Hz), 121.99 (CF3, 1JC–F 283.7 Hz), 101.59 (C-5, 2JC–F 34.9 Hz, 1J4–5 41.8 Hz), 43.65 (C-4, 1J3–4 34.8 Hz, 1J4–5 41.8 Hz). 19F NMR, d: –83.65. 15N NMR, d: –6.41 (2JN–H 15.8 Hz). IR (KBr, n/cm–1): 451, 471, 534, 576, 602, 700, 734, 800, 840, 886, 924, 980, 1010, 1057, 1130, 1182, 1199, 1256, 1304, 1330, 1416, 1430, 1628, 2861, 2930, 2957, 2991, 3100, 3577 (OH in CCl4).MS, m/z (%): 155 (1.8, [M+]), 138 (6.1, [M – OH+]), 125 (14.7), 111(14), 97 (12.5, [CF3CO+]), 92 (14.7), 86 (100), 69 (36.1), 68 (19.8), 67 (8.4), 63 (17.5), 58 (21.6), 56 (19.3), 54 (15.3), 44 (22.7), 42 (61.3). Found (%): C, 30.65; H, 3.06; N, 8.51; F, 36.67. Calc. for C4H4F3NO2 (%): C, 30.18; H, 2.52; N, 8.81; F, 36.77.Me N Me O Me N Me O F3C O pyridine 1 N N H CO2CF3 · O(COCF3)2 2 3 4 1 2 3 4 NaHCO3/H2O N O H3 H4' H4 OH CF3 5 Scheme 1 + (CF3CO)2O N O O H C F F FMendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) the above procedure,12 also through the 1,3-dipolar addition of nitrile oxides to alkenes13 and oximation of a,b-ethylenic carbonyl compounds14).References 1 M. Hojo, R. Masuda, Y. Kokuryo, H. Shioda and S. Matsuo, Chem. Lett., 1976, 499. 2 M. Hojo, R. Masuda and Y. Kamitori, Tetrahedron Lett., 1976, 1009. 3 M. Hojo and R. Masuda, J. Org. Chem., 1975, 40, 963. 4 B. A. Trofimov and A. I. Mikhaleva, N-Vinilpirroly (N-Vinylpyrroles), Nauka, Novosibirsk, 1984, p. 127 (in Russian). 5 B.A. Trofimov, in Pyrroles, Part Two: The Synthesis, Reactivity and Physical Properties of Substituted Pyrroles, ed. R. A. Jones, Wiley, New York, 1992, p. 131. 6 B. A. Trofimov, A. I. Mikhaleva, A. N. Vasil’ev and M. V. Sigalov, Izv. Akad. Nauk SSSR, Ser. Khim., 1979, 695 (Bull. Acad. Sci. USSR, Div. Chem. Sci., 1979, 28, 651). 7 O. A. Tarasova, S. E. Korostova, A. I. Mikhaleva, L.N. Sobenina, R. N. Nesterenko, S. G. Shevchenko and B. A. Trofimov, Zh. Org. Khim., 1994, 30, 810 (Russ. J. Org. Chem., 1994, 30, 863). 8 M. Witanovski, L. Stefaniak and G. A. Webb, in Annual Reports on NMR Spectroscopy, ed. G. A. Webb, Academic Press, London, 1981, vol. 11B, p. 502. 9 Ban Chin Chen and W. von Philipsborn, Helv. Chim. Acta, 1983, 66, 1537. 10 D. A. K. Jones and J. G. Watkinson, J. Chem. Soc., 1964, 2371. 11 P. A. S. Smith, The Chemistry of Open-Chain Organic Nitrogen Compounds, Benjamin, Inc., New York, 1966, ch. VII, p. 100. 12 V. Ya. Sosnovskikh, M. Yu. Mel’nikov and A. V. Zaitsev, Mendeleev Commun., 1999, 40. 13 R. Huisgen, Angew. Chem., 1963, 75, 604. 14 A. Belly, R. Jacquier, F. Petrus and J. Verducci, Bull. Soc. Chim. France, 1972, 330. Me N Me O F3C O 2 H2 O OH 6 O F3C O 7 NOH Me Me 8 NOH F3C O 9 O Me Me Scheme 2 5 Received: 25th May 1999; Com. 99/1490

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) The mechanism of a diad prototropic rearrangement of hydrophosphorylic compounds Victor M. Mamaev,*a Andrew V. Prisyajnuk,b Dmitry N. Laikov,a Ludmila S. Logutenkob and Yuri V. Babinb a Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation. Fax: + 7 095 0932 8846; e-mail: vmam@nmr.chem.msu.su b Far-East Academy of Economics and Management, 690091 Vladivostok, Russian Federation.Fax: +7 4232 40 6634; e-mail: yub@mail.primorye.ru A prototropic rearrangement of a number of hydrophosphorylic compounds has been found to proceed by a bimolecular mechanism with tunneling predominant at temperatures below 340 K. Organophosphorus compounds play an important role in biochemical processes.The chemistry of phosphorus depends on the development of adequate quantum-chemical models of the electronic structure of phosphorus compounds in order to predict the structure and ways of synthesis of new phosphorus compounds. Hydrophosphorylic compounds are the main raw materials for synthesis of different classes of chemical products such as catalysts, extractants and drugs.This paper is devoted to a theoretical study of a diad prototropic tautomeric rearrangement of hydrophosphorylic compounds. Most of trivalent phosphorus acids are well known to be stable as hydrophosphorylic compounds 1 (R, R' = Alk, AlkO):1 According to ICR data,2 in the case of R, R' = MeO, the energy of tautomerization is equal to 6.5 kcal mol–1.On the other hand, for bis-pentafluorophenylphosphinic acid3 and some cyclic esters of phosphorous acid4 an equilibrium between 1 and 2 can be observed. If R and R' are strong acceptor substituents (like CF3), the equilibrium is almost completely shifted toward 2.5 Since experimental determination of the mechanism and energy of tautomerization of the prototropic rearrangement in hydrophosphorylic compounds is difficult, a theoretical study of such systems is of great interest.Thus, theoretical studies of various fluorine-substituted dimethylphosphinic acids can provide an opportunity to elucidate the regularities of the prototropic equilibrium, self-association and other important aspects of acid–base interactions.6 We report here on calculations of the structures of the stationary points on the potential-energy surfaces of reactions (1)–(5).The calculations were performed with a RHF wave function in the 6-31G** basis set with taking into account the correlation effects at the MP2 level using the GAMESS program,7 as well as by DFT according to the PBE formula for the correlation exchange functional8 using the program from ref. 9. We assumed the rearrangement to occur by both unimolecular and bimolecular mechanisms. The geometry parameters of the obtained equilibrium structures are consistent with the experimental data for related compounds (Table 1). The results of the RHF + MP2 and DFT calculations are in a good agreement with each other (Table 2). Note that the DFT reproduces the experimental value of the tautomerization energy for reaction (5).2 According to Table 2, in the cases of (3) and (4), the reaction equilibrium in the system will be shifted toward 2, while for (1) it will be shifted toward 1. It is interesting that for reaction (3) both computational methods predict the reaction equilibrium to be shifted toward 2 to a greater extent than for (4). In the case of a unimolecular mechanism of (1)–(5) the rearrangement goes from a bound state of 1 to 2 via a transition state (TS).All the structures have a symmetry plane: According to DFT data, the activation barriers for (1)–(5) are as high as 50–60 kcal mol–1. If we consider a bimolecular mechanism of the rearrangement, a TS of C2 symmetry is formed (TS2). Its structure is given below: In this case, the activation barrier is lowered by ca.an order of magnitude. The geometry and energy parameters of TS and P OH R' R 1 P O R' R 2 H Me2POH Me2P(O)H; (CH2F)2POH (CH2F)2P(O)H; (CHF2)2POH (CHF2)2P(O)H; (CF3)2POH (CF3)2P(O)H; (MeO)2POH (MeO)2P(O)H. (1) (2) (3) (4) (5) aIn PMe3. bIn P(CF3)3. cIn P(OMe)3. dIn O=PMe3. eIn O=P(CF3)3. fIn O=P(OMe)3. Table 1 Bond lengths in the test compounds.Bond (reaction) Experimental bond length10/Å RHF (6-21G**) + MP2 data/Å DFT data/Å P–C (1) 1.844a 1.831 1.855 P–C (4) 1.904b 1.866 1.922 P–O (5) 1.620c 1.639 1.656 P=O (1) 1.476d 1.482 1.511 P–C (1) 1.809d 1.831 1.855 P=O (4) 1.517e 1.475 1.495 P–O (4) 1.5725e 1.610 1.620 P=O (5) 1.477f 1.475 1.495 P–O (5) 1.5806f 1.639 1.656 O–C (5) 1.4326f 1.443 1.450 1 2 O P O P O P TS O P O P TS2Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) TS2 for reaction (1) are given in Table 3. Note that the replacement of hydrogen atoms with fluorine atoms changes these parameters only slightly. The proton-transfer reactions are known to occur with an essential tunnel effect.11 In order to evaluate the tunnel effect, we have to calculate the so-called transmission factor c(T) (i.e., the ratio of the cumulative thermal rate constant to its over-thebarrier component).12 For the case of small tunnel corrections, we can use the Wigner expression for c(T):13 where w� is the imaginary ‘vibrational frequency’ at the saddle point of TS, and kB is the Boltzmann constant.If c is equal to 2, the tunnel and activation contributions to the rate constants are equal at a given temperature.Calculations by the Wigner formula show that in the case of a unimolecular mechanism of reactions (1)–(5) c� 2 (i.e., tunneling is predominant) at T £ 420 K, while in the case of a bimolecular mechanism c � 2 at T £ 340 K. Thus, we can conclude that for reactions (1)–(5) the bimolecular mechanism is favourable, and tunneling contributes mainly to the rate constant at T £ 340 K.References 1 M. I. Kabachnik, in Khimiya i primenenie fosfororganicheskikh soedinenii (Chemistry and Applications of Organophosphorus Compounds), Izd. AN SSSR, Moscow, 1957, p. 18 (in Russian). 2 W. J. Pietro and W. J. Hehre, J. Am. Chem. Soc., 1982, 104, 3594. 3 D. D. Magnelly, G. Test, J. U. Lowe and W. E. McQuistion, Inorg. Chem., 1966, 5, 457. 4 E. E. Nifant’ev, A. I. Zavalishina, S. F. Sorokina and A. A. Borisenko, Zh. Obshch. Khim, 1976, 46, 471 [J. Gen. Chem. USSR (Engl. Transl.), 1976, 46, 469]. 5 J. E. Griffits and A. B. Burg, J. Am. Chem. Soc., 1960, 82, 1507. 6 E. E. Nifant’ev, Khimiya gidrofosforil’nykh soedinenii (Chemistry of Hydrophosphorylic Compounds), Nauka, Moscow, 1983 (in Russian). 7 M. W. Schmidt, K.K. Balridge, J. A. Boatz, S. T. Elbert, M. S. Gordon, J. J. Jensen, S. Koseki, N. Matsunaga, K. A. Nguyen, S. Su, T. L. Windus, M. Dupuis and J. A. Montgomery, J. Comput. Chem., 1993, 14, 1347. 8 J. P. Perdew, K. Burke and M. Ernzerhof, J. Chem. Phys., 1996, 105, 9982. 9 D.N.Laikov, Chem. Phys. Lett., 1997, 281, 151. 10 V. A. Naumov and L. V. Vilkov, Molekulyarnye struktury fosfororganicheskikh soedinenii (Molecular Structures of Organophosphorus Compounds), Nauka, Moscow, 1986 (in Russian). 11 W. H. Miller, N. C. Handy and J. E. Adams, J. Chem. Phys., 1980, 72, 99. 12 D. Truhlar, W. Hase and R. Hynes, J. Phys. Chem., 1983, 87, 2264. 13 R. P. Bell, The Tunnel Effect in Chemistry, Chapman and Hall, London, 1980. aA negative value means that form 2 is more stable than 1. bWith the addition of the zero point energy. Table 2 Energies of structures 2 with respect to 1 for reactions (1)–(5)/ kcal mol–1.a Reaction RHF + MP2 method DFTb 1 –8.8 –3.8 2 –2.5 3.9 3 5.0 8.6 4 2.5 6.7 5 –12.0 –6.1 aThe activation barriers are counted relatively to the energies of 1 for TS, and relatively to the doubled energies of 2 for TS2. The bond lengths are given in Å, the energies are in kcal mol–1 with allowance for the zero point energy. Table 3 The geometry and energy (E�) parameters of TS and TS2 structures for reaction (1).a Parameter TS TS2 P–H 1.48 1.59 O–H 1.46 1.35 P–O 1.62 1.69 4.5 c(T) = 1 + , 2 hw� 24kBT Received: 11th January 1999; Com. 99/14

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Preparation of mesoporous aluminosilicates in the presence of lecithin: a simulation of biomineralization processes Yuri G. Goltsov,* Lily A. Matkovskaya, Zinaida V. Smelaya and Vladimir G. Il’in L. V. Pisarzhevsky Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 252039 Kiev, Ukraine. Fax: +38 044 265 6216; e-mail: ipcukr@sovam.com Various combinations of lecithin with cetyltrimethylammonium bromide or octadecylamine were used as template agents in the preparation of biporous materials (pore size up to 100 Å) in the aluminosilicate system.Recent studies indicate that a biomimetic approach based on the main constructional processes of biomineralization results in the development of new strategies in the controlled synthesis of highordered inorganic materials.1–6 Considerable advantages of these methods consist in rather low process temperatures, the use of biomolecules rather than toxic surfactants as templates and the use of water in place of organic solvents.1–3 Thus, these synthetic routes and the resulting materials can be considered to be environmentally friendly.6 Aluminosilicate materials prepared in the presence of organic template molecules are of particular interest as appropriate supports for immobilised enzymes because of specific affinities to templates.7 One of the problems arising with the use of biomolecules in the synthesis of inorganic substances is the sensitivity of biomolecules to reaction conditions.We optimised the composition of reaction mixtures used for preparing MCM-41 aluminosilicate materials in order to attain near-neutral pH values of the reaction mixtures.These pH values are important for the retention of the physico-chemical properties and reactivity of biomolecules. The synthesis of MCM-41 aluminosilicate materials in the presence of cetyltrimethylammonium bromide (CTAB) was carried out using a reaction mixture of the following composition (pH was close to neutral): 16.2SiO2× ×Al2O3·5.4Na2O·13.8CTAB·1767H2O (sample 1), sodium silicate and aluminium sulfate served as sources of silica and aluminium, respectively.The hydrothermal synthesis was performed at 423 K for 48 h. The product obtained was washed with water, dried and calcined at 823 K in air for 6 h.The X-ray diffraction data (DRON-3M instrument, CuKa radiation) and the adsorption (desorption) isotherms (methanol, 293 K, activation at 373 K) of sample 1 (Figure 1, Table 1) indicate that the material exhibits a hexagonal array of uniform mesopores with diameter D = 34 Å. The Si:Al ratio in sample 1 (7.8) is close to that in the reaction mixture. Thus, at neutral pH of the reaction mixture, a highly ordered aluminosilicate MCM-41 material with high aluminium content was obtained.This fact is important both for the preparation of mesoporous substances in the presence of biotemplates and for the synthesis of various inclusion compounds.8 This work was devoted to examining the applicability of supramolecular structures of lecithin (L) molecules as templates to the synthesis of mesoporous aluminosilicates.For this purpose, lecithin (17% of L-a-phosphatidylcholine, Sigma) or its combinations with CTAB or octadecylamine (ODA) were added instead of CTAB to the reaction mixture, so that the L:CTAB and L:ODA molar ratios in the reaction mixture were 0.47 or 1.40 and 0.34 or 1.04, respectively. The hydrothermal synthesis was performed at 353 K for 72 h.The products obtained were washed with water, dried and calcined in air at 823 K for 6 h. To examine the effects of pH and the Si:Al ratio in the reaction mixture on the structure of the products, similar syntheses were carried out using the reaction mixture (pH ~ 9) 116SiO2·Al2O3·38Na2O·49CTAB·9101H2O (Table 1). The Kelvin equation (assuming a hemispherical meniscus shape and a zero contact angle) with the multilayer thickness correction was used for determining the pore size distribution.9 The mesopore volume Vmes of the samples was estimated from the isotherms (Figures 1 and 2) at p/ps = 0.89.The X-ray diffraction patterns of samples 3–6 and 9 exhibited a single peak at low angles (Table 1 summarises the corresponding interplanar distances d).It was found (Figure 2, Table 1) that mesoporous substances are formed in the presence of only lecithin; that is, the supramolecular structures of lecithin molecules are a template in the formation of an aluminosilicate framework. The self-assembly of amphiphilic lecithin molecules in spherical, cylindrical and bilayer structures and two-dimensional phases in a free solution is well studied (under the reaction conditions, lecithin molecules form lamellar bilayer structures such as flat layers or closed vesicles).10 However, it is unknown how the presence of inorganic species affects these aggregates, and which is the structure of supramolecular vesicles participating in the templating process.The structure of organic–inorganic composites is determined 20 15 10 5 0 0.2 0.4 0.6 0.8 1.0 p/ps n/mmol g–1 1 3 5 7 2q/° (a) (b) dV/dD 30 40 D/Å d100 = 39 Å Figure 1 (a) X-ray diffraction pattern and (b) methanol adsorption (desorption) isotherm for sample 1.Insert: Pore size distribution of sample 1, calculated from the methanol desorption branch.Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) by the organic–organic interactions to form arrays of organic molecules, organic–inorganic interactions at the appropriate interfaces, and inorganic–inorganic interactions resulting in the polymerization of inorganic species.11 It is obvious that the role of each type of these interactions in the formation of porous structures depends on the synthesis conditions and the nature of the template.The structure of pre-organised lecithin molecule arrays that form an aluminosilicate framework depends on the Si:Al ratio and the pH of the reaction mixture (Figure 2). The alkalinity of the reaction mixture controls the geometry and charge density of aluminosilicate species and template head groups (Me3N+ groups of lecithin and CTAB and NH2 groups of ODA).Sample 8 (Si:Al = 58) has larger and more homogeneous pores than sample 2 (Si:Al = 8). In our opinion, this difference can be explained by the fact that at Si :Al = 58 in alkaline media the initial arrangement of lecithin molecules is disrupted upon strong ionic interactions with negatively charged aluminosilicate particles. Next, they undergo reorganisation to form new configurations uniform in size, which are similar to cylindrical CTAB structures11 formed in the alkaline synthesis of MCM-41 materials.The disordering of the structure at Si:Al = 8 can be explained not only by an increase in the aluminium content but also by the fact that the slightly negatively charged aluminosilicate particles insignificantly perturb the self-organisation of lecithin vesicles, which exhibit a spread in size.It is our opinion that the structure formation processes in the above systems are similar to naturally occurring biomineralization processes because the supramolecular structures of lecithin participate in the templating process, and the interaction between aluminosilicate oligomers and the template surface depends on the Si:Al ratio and the pH of the reaction mixture.It is likely that the bilayer structures of lecithin molecules (the thickness is approximately equal to 40 Å)10 play a templating role in the formation of 40 Å diameter pores in samples 2 and 8. The fact that pores of this size in sample 8 exhibit a small adsorption volume indicates that bilayer structures are also formed in a reaction mixture with Si:Al = 58, however, the amount of these structures is insignificant because of strong organic–inorganic interactions.These assumptions concerning a key role of organic–inorganic and organic–organic interactions in the formation of aluminosilicate frameworks were also supported by the data on the porous structure of substances obtained in the presence of lecithin mixtures with CTAB or ODA (Figure 2, Table 1).We found that mesoporous substances with pore diameters up to 100 Å and biporous materials which have bimodal mesopore size distribution can be prepared in the presence of the above combinations as template agents in the aluminosilicate system. The formation of biporous materials indicates that along with mixed micelles12 other types of micelles (for example, micelles that consist of CTAB or ODA and also liposomes or disc-shaped lecithin structures with small inclusions of CTAB or ODA) can occur in the reaction mixture.The participation of such structures in the framework formation depends upon the pH of the reaction mixture. The adsorption (desorption) isotherms of samples with Si:Al = = 8 (pH close to neutral) exhibit well-defined steps due to various types of the templating agents (Figure 2), whereas the shape of the isotherms of samples with Si:Al = 58 (pH ~ 9) is independent of the template and is characterised by a sharp rise at p/ps > 0.8 and by a larger mesopore volume (for samples obtained in the presence of the same template).Thus, the inexpensive and environmentally benign template procedure described leads to mesoporous materials with large pore volumes and hybrid porous structures.References 1 S. Mann, D. D. Archibald, J. M. Didymus, T. Douglas, B. R. Heywood, F. C. Meldrum and N. J. Reeves, Science, 1993, 261, 1286. 2 S. Mann, Nature, 1993, 365, 499. 3 D. D. Archibald and S. Mann, Nature, 1993, 364, 430. 4 P. T. Tanev and T. J. Pinnavaia, Science, 1996, 271, 1267. 5 I.A. Aksay, M. Trau, S. Manne, I. Honma, N. Yao, L. Zhou, P. Fenter, P. M. Eisenberger and S. M. Gruner, Science, 1996, 273, 892. 6 Y. Wei, D. Jin, T. Ding, W.-H. Shin, X. Liu, S. Z. D. Cheng and Q. Fu, Adv. Mater., 1998, 3, 313. 7 K. Morihara, M. Kurokawa, Y. Kamata and T. Shimada, J. Chem. Soc., Chem. Commun., 1992, 358. 8 J. M. Thomas, Nature, 1994, 368, 289. 9 S. J. Gregg and K.S. W. Sing, in Adsorption, Surface Area, and Porosity, Academic Press, New York, 1982, 2nd edn., p. 113. 10 D. M. Small, J. Lipid Res., 1967, 8, 551. 11 G. D. Stucky, Q. Huo, A. Firouzi, B. F. Chmelka, S. Schacht, I. G. Voigt- Martin and F. Schüth, in Progress in Zeolite and Microporous Materials, Studies in Surface Science and Catalysis, eds. H. Chon, S.-K. Ihm and Y.S. Uh, Elsevier Science, Amsterdam, 1997, vol. 105, p. 3. 12 D. Lichtenberg and Y. Barenholz, Methods Biochem. Anal., 1988, 33, 337. dV/dD D/Å 0 50 100 150 1 2 3 4 5 dV/dD D/Å 0 50 100 150 55 50 45 40 35 30 25 20 15 10 5 0 0.1 0.2 0.4 0.6 0.8 1.0 p/ps 0.1 0.1 0.1 0 0 0 0 0 n/mmol g–1 Figure 2 Methanol adsorption (desorption) isotherms for samples (1) 2, (2) 3, (3) 5, (4) 9, (5) 8 and (6) 11. Insert: Pore size distribution of samples (1) 3, (2) 9, (3) 6, (4) 5, and (5) 11, calculated from the methanol desorption branch. 1 2 3 4 5 6 aThe Si:Al ratio in the reaction mixture. bMaterials with a bimodal mesopore size distribution. Table 1 Characteristics of the materials obtained. Sample no. Si:Ala Template D/Å d/Å Vmes/cm3 g–1 1 8.1 CTAB 34 39 0.58 2b 8.1 L 38; 44 — 0.48 3b 8.1 L:CTAB = 0.47 36; 98 54 0.62 4b 8.1 L:CTAB = 1.40 31; 40 54 0.61 5b 8.1 L:ODA = 0.34 41; 65 57 0.76 6 8.1 L:ODA = 1.04 42 59 0.47 7 58 CTAB 34 39 1.00 8b 58 L 46; 66 — 0.47 9 58 L:CTAB = 0.47 91 59 1.07 10 58 L:CTAB = 1.40 80 — 0.92 11b 58 L:ODA = 1.04 58; 114 — 0.66 Received: 7th April 1999; Com. 99/1474

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年代:1999

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Electrochemical investigation of microemulsions in the C12H25SO3Na–BuOH–C7H16–H2O system at different water contents Chunsheng Mo and Nataliya N. Kochurova* Department of Chemistry, St. Petersburg State University, 198904 St. Petersburg, Russian Federation. Fax: +7 812 428 6939; e-mail: oleg@nk2235.spb.edu The phase inversion from water-in-oil to oil-in-water microemulsions in the title system was examined by cyclic voltammetry and conductivity measurements.Diffusion measurements are widely used for characterising aqueous surfactant solutions. Quasi-elastic light scattering,1 pulsed field gradient NMR,2 small angle X-ray scattering,3 neutron scattering,4 Taylor dispersion5 and electrochemical measurements6 are also among the most commonly used techniques.In this work, the sodium dodecyl sulfonate–butanol–heptane–water system was examined by cyclic voltammetry using electroactive probes for determining the diffusion coefficients of microemulsion droplets and for detecting phase inversion in the microemulsion region. Electric conductivity measurements were also carried out to support the results obtained by cyclic voltammetry.In cyclic voltammetry, the peak current for a reversible system is described by the Randles–Sevcik equation7 where n is the number of electrons involved in the oxidation or reduction, F is the Faraday constant, A is the electrode surface area, C0 is the concentration of an electroactive probe, R is the gas constant, T is the absolute temperature, D is the diffusion coefficient of the electroactive probe, u is the scan rate, and ip is the peak current.It follows from equation (1) that ip linearly increases with u1/2 at a given electrode surface area and a constant probe concentration, a plot of ip against u1/2 is linear, and the diffusion coefficient D can be calculated from the slope of this straight line.In microemulsion systems with an electroactive probe completely solubilised in the microemulsion droplets, the diffusion coefficient D in equation (1) corresponds to the diffusion coefficient of microemulsion droplets because the probe diffuses with the droplets. In order to examine the microstructure of microemulsion droplets, we used oil-soluble ferrocene (Fc) and watersoluble potassium ferricyanide [K3Fe(CN)6] as the electroactive probes in cyclic voltammetry.The initial test sample was a mixture of an emulsifier (a surfactant and a cosurfactant) and heptane, in which the initial oil content was 21 wt% (3 g of C12H25SO3Na, 6 g of BuOH and 2.4076 g of C7H16). Next, water was added drop by drop to the mixture. A continuous single-phase optically transparent microemulsion was formed when the water content was within the range 20–83%.Figure 1 demonstrates the plots of ip against u1/2 for the two electroactive probes at different water contents. Figure 2 shows the diffusion coefficients of the probes as functions of the water content of microemulsions. The plots in Figure 1 are straight lines passing through the origin.This fact indicates that the electron transport properties of Fc+/Fc and [Fe(CN)6]3–/[Fe(CN)6]4– electrode reactions in the microemulsions are diffusion controlled. The measurement error in the peak current ip was evaluated as ±0.02 mA. Thus, diffusion coefficients D found from these lines are reliable. As can be seen in Figure 2, the diffusion coefficient of ferrocene decreases with increasing water content over the entire single-phase microemulsion region.At water contents lower than 45%, this decrease is gradual; an abrupt decrease in the diffusion coefficient is observed in the range from 45 to 65%, and a gently sloping curve is also observed at water contents above 65%. Similar inflection points are also observed in Figure 2 for potassium ferricyanide used as the electroactive probe; however, the diffusion coefficient of K3Fe(CN)6 in microemulsions increases with increasing water content. The difference between the diffusion behaviour of ferrocene and potassium ferricyanide over the same microemulsion region can be explained by the solubility in water and oil.Ferrocene was expected to probe the oil environment because of its limited water solubility.At low water contents, a water-in-oil microemulsion is formed, and the oil is the medium. In this case, the diffusion coefficient of ferrocene was found to be relatively high. In contrast to ferrocene, the diffusion coefficient of K3Fe(CN)6 in an oil medium corresponds to the diffusion coefficient of water-in-oil microemulsion droplets because K3Fe(CN)6 diffuses ip = 4.463×10–4nFAC0(nF/RT)1/2D1/2u1/2, (1) 20 18 16 14 12 10 8 6 4 2 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 u1/2/V1/2 s–1/2 ip/mA 1 2 Figure 1 Peak current ip vs.u1/2 for the C12H25SO3Na–BuOH–C7H16–H2O system in the presence of ferrocene or K3Fe(CN)6·3H2O: (1) 0.0055 g of ferrocene and 34.20 g (75%) of H2O, (2) 0.0364 g of K3Fe(CN)6·3H2O and 3.80 g (25%) of H2O. 12 10 8 6 4 2 0 20 30 40 50 60 70 80 H2O (%) D/10–11 m2 s–1 1 2 Figure 2 Diffusion coefficients of probes as functions of water content F of the system (30 °C) in the presence of (1) 0.005 g of ferrocene or (2) 2.50×10–2 mol dm–3 K3Fe(CN)6.Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) with the aqueous phase. The diffusion coefficients of both ferrocene and K3Fe(CN)6 in the water content range from 20 to 45% change slowly.This fact indicates that the microenvironment of microemulsions remains unchanged. A similar behaviour was observed in this microemulsion at a high water content (above 65%). In the latter case, the oil microdroplets were dispersed in a water medium, and the diffusion coefficient of ferrocene can be considered as that of oil-in-water microemulsion droplets.However, a dramatic change in the diffusion coefficients of both ferrocene and K3Fe(CN)6 was observed at water contents in the range from 45 to 65% (Figure 2). This fact is indicative of a change in the microenvironment of microemulsions. In other words, neither water-in-oil nor oil-in-water microemulsions exist in this region. We can suggest that a bicontinuous microstructure was formed, in which both aqueous and oil solutions are local continuous phases.8 We also measured the electric conductivity of the above microemulsions, and Figure 3 demonstrates typical experimental results.The electric conductivity k plotted against water content exhibits features characteristic of percolate conduction. The relationship between the conductivity and the water content in the water-inoil microemulsion region takes the form9,10 where F is the water content, Fc is the percolation threshold or the critical water content, k0 and a are constants.At F < Fc, a � 1, the conductivity of microemulsions is very low, and the electric conductivity k slowly increases with F. However, in the case of F > Fc, a = 1, and the electric conductivity k linearly and steeply increases up to F = Fb, k = kb.Various mechanisms have been proposed to explain the percolate conduction observed in some water-in-oil microemulsions. One of the commonly accepted mechanisms is the model of ‘sticky droplet collisions’ suggested by Fletcher and Robinson.11 According to this model, frequent sticky collisions between spherical microdroplets of waterin- oil microemulsions above the percolation threshold Fc can occur due to the attractive interactions.These sticky collisions may lead to the formation of narrow water tubes or channels in an oil medium, and counter-ions can migrate through these narrow channels to result in an abrupt and steep increase in the electric conductivity. Evidently, a water-in-oil microemulsion is formed in this region of low water contents.At high water contents, for example, at F > Fm, the value of k, after arriving the maximum value km, decreases with increasing water content. This obvious decrease in the electric conductivity k results from dilution with the added water, which decreased the concentration of the dpersion phase. Accordingly, an oil-in-water microemulsion was formed in this region of high water contents.However, in the region of moderate water contents at Fb < F < Fm, the conductivity curve exhibits an abnormal behaviour: the electric conductivity k nonlinearly increases up to a maximum. This feature of conductivity curves was often used to identify the occurrence of a bicontinuous microemulsion.The conductivity curve in Figure 3 clearly illustrates the occurrence of the three regions: water-in-oil (20–43% water), oil-inwater (64–83%) and bicontinuous (43–64%) microemulsions. Thus, the results obtained by the two electrochemical methods are in agreement. In summary, cyclic voltammetry was found to be a promising technique for examining structural transformations in macro- and microemulsion systems.References 1 E. Dayalan, S. Qutubuddin and J. Texter, J. Colloid Interface Sci., 1993, 158, 249. 2 M. Leaver, I. Furo and U. Olsson, Langmuir, 1995, 11, 1524. 3 J. Marignan, J. Appell, P. Bassereau, G. Porte and R. P. May, J. Phys. (Paris), 1989, 50, 3553. 4 H. Okamura, T. Imae, K. Takagi, Y. Sawaki and M. Furusaka, J. Colloid Interface Sci., 1996, 180, 98. 5 D. G. Leaist and H. Ling, J. Phys. Chem., 1993, 97, 7763. 6 A. C. Onuoha and J. F. Rusling, Langmuir, 1995, 11, 3296. 7 P. T. Kissinger and W. R. Heineman, J. Chem. Educ., 1983, 60, 701. 8 P. Guering and B. Lindman, Langmuir, 1985, 1, 464. 9 M. Lagues and C. Sauterey, J. Phys. Chem., 1980, 84, 3503. 10 B. Lagourette, J. Peyrelasse, C. Boned and M. Clausse, Nature, 1979, 281, 61. 11 P. D. I. Fletcher and B. H. Robinson, Ber. Bunsen–Ges. Phys. Chem., 1981, 85, 863. 1.2 1.0 0.8 0.6 0.4 0.2 0.0 10 20 30 40 50 60 70 80 H2O (%) k/S m–1 kb km Fb Fc Fm Figure 3 Electric conductivity k as a function of water content F of the system (30 °C). k = k0(Fc – F)aF < Fc, k = k0(F – Fc)aF > Fc, (2) Received: 15th June 1999; Com. 99/1502

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年代:1999

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) The influence of sodium salicylate on the micellar rate effect and the structural behaviour of dodecylpyridinium bromide micelles Lucia Ya. Zakharova,*a Dmitry B. Kudryavtsev,b Lyudmila A. Kudryavtseva,a Alexander I. Konovalov,a Yury F. Zuev,c Natalia N. Vylegzhanina,c Natalia L. Zakharchenkoc and Zyamil Sh. Idiatullinb a A.E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Centre of the Russian Academy of Sciences, 420088 Kazan, Russian Federation. Fax: +7 8432 75 2253; e-mail: vos@iopc.kcn.ru b Kazan State Technological University, 420015 Kazan, Russian Federation c Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, 420503 Kazan, Russian Federation A correlation between salt-induced structural transitions of dodecylpyridinium bromide micelles and their catalytic effect on the basic hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate has been found.Although the electrolyte effects on the micellar catalysis are widely investigated,1–3 some urgent aspects of the problem remain hitherto unsolved. The most important problem is the influence of salt-induced micellar transitions on the micellar rate effect. It is well known4–6 that addition of electrolytes results in a change in micellar characteristics such as a critical micellar concentration (cmc), an aggregation number, a degree of counter-ion binding, a micellar shape etc.At a definite counterion concentration, a gradual change in the above parameters with counter-ion concentration turns into a sharp change, which is revealed by a break in the ‘property’ vs.lg Csalt plot. In accordance with the literature,4 these threshold electrolyte concentrations are associated with micellar sphere-to-rod transitions. It is reasonably to assume that alterations in the above micellar parameters should exert an influence on the reactivity in the micelles. In our earlier studies,7,8 a mechanism of the electrolyte effect on nucleophilic substitution reactions and acid–base equilibria in cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) micelles has been investigated. The aim of this work was to study the kinetics of basic hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate 1 in dodecylpyridinium bromide (DPB) micellar solutions (Scheme 1) in a wide range of sodium salicylate (NaSal) concentrations and the structural behaviour of the micelles used as nanoreactors by surface tension measurements and NMR and EPR spectroscopy.Cationic micelles exhibit a unique behaviour in the presence of Sal-anions, which requires further investigation. Substrate 1 was prepared according to the published procedure.9 The surfactant DPB of ‘pure’ grade was twice recrystallised from ethanol.The surface tension measurements were performed by the anchor-ring method.10 The surface tension isotherms were used to determine the counter-ion binding with the ±0.01 accuracy.11 The Fourier transform proton pulsed-gradient spinecho (FT-PGSE) measurements were performed using a modified TESLA-BS 576A NMR spectrometer at 100 MHz to give the self-diffusion coefficients of micellar components.12 The X-band EPR spectra were recorded on an RE 1306 spectrometer under conditions described elsewhere.13 5-Doxyl-stearic acid (Sigma) was used as a spin label in a concentration of 5×10–4 mol dm–3.The reaction was monitored by observing the p-nitrophenolate anion absorption using a ‘Specord M-400’ spectrophotometer equipped with temperature-controlled cell holders.The kinetic data were treated in terms of the pseudophase model using the equation14 where k'obs (dm3 mol–1 s–1) is the second-order rate constant obtained by division of the observed pseudo-first-order rate constant kobs by the total nucleophile concentration; k2,w and k2,m (dm3 mol–1 s–1) are the second-order rate constants in the aqueous and micellar phases, respectively; KS and KOH (dm3 mol–1) are the substrate and nucleophile binding constants, respectively; V is the molar volume of the surfactant assumed to be equal to 0.3 dm3 mol–1; C is the DPB concentration below the cmc.Problems and approximations involved in these definitions have been discussed earlier.14 Figures 1 and 2 represent the kinetic data, which demonstrate a decrease in the observed rate constant with addition of NaSal.According to the pseudophase model,14 such an inhibition can result from a decrease in the micellar surface potential with counter-ion concentration, which in turn is responsible for weakening the electrostatic attraction of hydroxide ions with positively charged micelles, in which the reaction occurs.In addition, the displacement of the substrate by Sal– ions from the micellar surface is probably observed. The results of the quantitative treatment of the kinetic data in terms of equation (1) summarised in Table 1 show a reduction in the substrate binding constants and the rate constants in the micellar pseudophase as the counter-ion concentration increases.Note that in the absence of electrolytes both the concentrating factor (Fc) and the micellar microenvironment (Fm) make positive contributions to the micellar rate effect, which is unusual for the ion–molecule nucleophilic substitution reactions in cationic micelles.2 O NO2 P ClH2C EtO O + 2OH O NO2 + H2O O P ClH2C EtO O 1 Scheme 1 0.2 0.1 0.0 0.00 0.02 0.04 0.06 0.08 CDPB/mol dm–3 kobs/s–1 CNaSal/mol dm–3: 0 0.005 0.01 0.02 Figure 1 The observed rate constant of basic hydrolysis of 1 in micellar solutions of DPB as a function of surfactant concentration at different NaSal concentrations (0.005 mol dm–3 NaOH, 25 °C).k' obs = , k2,w + k2,mKSKOHC/V (1 + KSC)(1 + KOHC) (1)Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) An analysis of the kinetic data on semilogarithmic coordinates has been carried out (Figure 2), which revealed critical NaSal concentrations (Ccr) corresponding to the breaks in the kobs vs. lg Csalt plot. For comparison, analogous data for Br– and Cl– counter-ions were obtained. According to refs.7 and 8, Ccr values can be associated with the above structural transitions in the DPB micelles.The value of Ccr for Sal– is equal to 0.05 mol dm–3 (for Cl– and Br–, Ccr values are equal to 1.1 and 0.5 mol dm–3, respectively). In order to test correlation between the micellar structure and reactivity, the structural behaviour of the DPB micelles has been studied by surface tension measurements, NMR and EPR spectroscopy.The surface tension experiments yielded the cmc values of micellar DPB solutions at various NaSal concentrations. Based on published data,6 the empirical equation lg cmc = = –0.85lg Csalt – 5.32 has been drawn. An analysis of the surface tension isotherms using the known methodology11 enables us to calculate the degree of counter-ions binding (b) at various NaSal concentrations (Table 1).A marked increase in the b value is observed as bromide ions are replaced by Sal– ions. Using the Nernst correlation between the surface potential and cmc d|Y|/dlg cmc = 59.16 mV,15 the DPB surface potential has been calculated at different NaSal concentrations. The results are shown in Figure 3 together with the data for hydrophilic counter-ions, added for comparison.Similarly to published data,8 we found a coincidence of Y values corresponding to the Ccr values for Br and Cl, which are 74 and 71 mV, respectively. This fact indicates a prevalent role of the surface potential in the inhibition mechanism of inorganic counter-ions. The Ccr value for Sal– corresponds to –7 mV. This result is consistent with the published data on negative surface potentials Y16 and x-potentials17,18 of cationic micelles in the presence of Sal– ions.An unique effect of Sal– on CTAB, CPB and tetradecyltrimethylammonium halide micelles, which dramatically differs from that of hydrophilic inorganic counter-ions is extensively studied,17,18 whereas the behaviour of DPB micelles in the presence of NaSal is almost unknown. We examined the influence of Sal– on the structure of DPB micelles. The micellar size and shape were determined on the basis of the DPB self-diffusion coefficients (D) (Table 2) obtained from the diffusive decay of a line due to the (CH2)n protons in the NMR spectra of DPB.The experimental details were published elsewhere.12,19,20 The Stokes–Einstein equation where h is the solvent viscosity, gives the effective radius of DPB micelles in the absence of NaSal R = 15.4 Å, which is very close to the DPB molecule length calculated from the bond 1 2 3 0.12 0.08 0.04 0.00 –2.0 –1.6 –1.2 –0.8 –0.4 0.0 0.4 kobs/s–1 lg Csalt Figure 2 The observed rate constant of basic hydrolysis of 1 in micellar solutions of DPB as a function of the logarithm of salt concentration (0.005 mol dm–3 NaOH, 25 °C): (1) KCl, (2) KBr and (3) NaSal. 125 100 75 50 25 0 –25 –30 –25 –20 –15 –10 –5 0 5 lg Csalt Y/mV KCl KBr NaSal Figure 3 The surface potential of DPB micelles as a function of the logarithm of electrolyte concentration. aThe Fc and Fm values were calculated using the modified equation The left member (the ratio between the pseudo-first-order rate constants in the micellar system and water) describes the maximum acceleration of the reaction. The first multiplier is associated with the influence of the micellar microenvironment (Fm), and the second multiplier reflects concentrating the reagents in micelles (Fc).Table 1 Kinetic data for the different NaSal concentrations (Figure 1) treated in terms of the pseudophase model. CNaSal/mol dm–3 k2,m/dm3 mol–1 s–1 KS /dm3 mol–1 KOH/dm3 mol–1 Fa c Fam (kobs /kw)max FcFam b 0 11.7 233 1.4 3.9 2.9 10.4 11.5 0.71 0.005 5.0 200 3.0 7.9 1.3 8.6 9.8 0.92 0.01 4.5 83 3.0 7.0 1.1 7.0 8.0 0.94 0.02 1.1 63 11.0 19.0 0.3 4.0 5.0 0.96 (kobs /kw)max= .k2,m k2,w KSKOH V(KS 1/2 + K1/2 OH)2 70 60 50 40 30 20 10 0 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.01 0.1 CNaSal/mol dm–3 Axis ratio Time correlation/ns Figure 4 The spin-label correlation time (t = 1.1 ns with no NaSal added) and the axis ratio of DPB micelles as functions of NaSal concentration.D = kT/6phR, (2)Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) parameters (15.5 Å). This fact is indicative of a spherical shape of DPB micelles with no NaSal added. In the presence of NaSal, equation (2) gives improbably high values of R.Because of this, we used D to obtain the axis ratio P = B/2A (Figure 4) considering the DPB micelles as prolate ellipsoids.21 Here, B is the length of an ellipsoidal micelle, and A is equal to the radii of a spherical micelle in the absence of NaSal. Figure 4 shows that an increase in the Sal– concentration results in changes of the micellar shape from spherical to intermediate sphere-cylindrical (P = 1–5) at the first stage and to strongly stretched at CNaSal ~ 0.05 mol dm–3.The sphere-to-rod transition is reflected in the packing density of surfactant molecules in the micelle structure.22 To characterise it, we made EPR measurements and found the correlation time of spin-label rotation t = 6.65DH+[(I+/I–)–1/2 – 1]×10–10 s, where DH+ is the width of the low-field component in the EPR spectrum, I+ and I– are the intensities of the low- and high-field hyperfine components, respectively.The mobility of a spin label connected with the carbon atom of stearic acid at the 5-position can characterise the packing degree of DPB molecules close to polar head groups of the micelles. Figure 4 exhibits two linear regions in the NaSal concentration dependence of t.At the first stage (below ~0.05 mol dm–3 NaSal), an increase in the correlation time shows that the fraction of cylindrical micelles increases as compared with spherical micelles, i.e., the micelles lengthened. At the second stage when micelles become long enough, the contribution from spherical particles exerts no effect on the average correlation time.Thus, the NMR self-diffusion and EPR data give evidence for the structural transition in DPB micelles at a 0.05 mol dm–3 NaSal concentration. Comparing Figures 2 and 4, it can be seen, that Ccr values (Figure 2) are in the NaSal concentration range corresponding to dramatic structural changes in the DPB micelles. This work was supported by the Russian Foundation for Basic Research (grant no. 99-03-32037a). References 1 C. A. Bunton, in Reaction Kinetics in Micelles, ed. E. N. Cordes, Plenum Press, New York, 1973, p. 73. 2 L. S. Romsted, in Surfactants in Solution, ed. K. L. Mittal, Plenum Press, New York, 1984, vol. 4, p. 1015. 3 C. A. Bunton, F. Nome, F. N. Quina and L. S. Romsted, Acc. Chem. Res., 1991, 24, 357. 4 S. Ikeda, in Surfactants in Solution, ed.K. L. Mittal, Plenum Press, New York, 1984, vol. 3, p. 825. 5 G. Porter and J. Appel, in Surfactants in Solution, ed. K. L. Mittal, Plenum Press, New York, 1984, vol. 2, p. 805. 6 K. Shinoda, T. Nakagawa, B. Tamamushi and T. Isemura, Colloidal Surfactants, Academic Press, New York, 1963. 7 L. Ya. Zakharova, S. B. Fedorov, L. A. Kudryavtseva, V. E. Bel’skii and B.E. Ivanov, Izv. Akad. Nauk, Ser. Khim., 1993, 2161 (Russ. Chem. Bull., 1993, 42, 1329). 8 L. Ya. Zakharova, L. A. Kudryavtseva and A. I. Konovalov, Mendeleev Commun., 1998, 163. 9 V. E. Bel’skii, L. A. Kudryavtseva, O. M. Il’ina and B. E. Ivanov, Zh. Obshch. Khim., 1970, 49, 2470 (in Russian). 10 V. I. Baranova, E. E. Bibic, N. M. Kozhevnikov, I. S. Lavrov and V. A. Malov, Praktikum po kolloidnoi khimii (Laboratory Manual on Colloid Chemistry), Vysshaya Shkola, Moscow, 1983 (in Russian). 11 A. I. Rusanov and V. B. Fainerman, Dokl. Akad. Nauk SSSR, 1989, 308, 651 (in Russian). 12 V. D. Fedotov, Yu. F. Zuev, V. P. Archipov, Z. Sh. Idiyatullin and N. Garti, Colloids Surf., 1997, 128, 39. 13 V. D. Fedotov, N. N. Vylegzhanina, A. E. Altshuler, V. I. Shlenkin, Yu. F. Zuev and N.Garti, Appl. Magn. Reson., 1998, 14, 497. 14 K. Martinek, A. K. Yatsimirsky, A. V. Levashov and I. V. Beresin, in Micellization, Solubilization, and Microemulsions, ed. K. L. Mittal, Plenum Press, New York, 1977, vol. 2, p. 489. 15 R. A. Hobson, F. Grieser and T. W. Healy, J. Phys. Chem., 1994, 98, 274. 16 T. Imae and T. Kohsaka, J. Phys. Chem., 1992, 96, 10030. 17 M. A. Cassidi and G. G. Warr, J. Phys. Chem., 1996, 100, 3237. 18 L. J. Magid, Z. Han, G. G. Warr, M. A. Kassidi, P. B. Bulter and W. A. Hamilton, J. Phys. Chem. B, 1997, 101, 7919. 19 P. Stilbs and M. E. Moseleg, Chem. Scripta, 1978, 11, 26. 20 V. D. Fedotov, Yu. F. Zuev, V. P. Archipov and Z. Sh. Idiyatullin, Appl. Magn. Reson., 1996, 11, 7. 21 N. A. Mazer, M. C. Carey and G. B. Benedek, in Micellization, Solubilization, and Microemulsions, ed. K. L. Mittal, Plenum Press, New York, 1977, vol. 1, p. 359. 22 V. N. Tsvetkov, V. E. Eskin and S. Ya. Frenkel, Struktura makromolekul v rastvore (Structure of Macromolecules in Solution), Nauka, Moscow, 1964 (in Russian). Table 2 The self-diffusion coefficients of DPB DDPB in water at different NaSal concentrations (CDPB = 0.05mol dm–3). CNaSal/mol dm–3 DDPB/10–11 m2 s–1 0 14.0 0.01 11.4 0.03 6.21 0.05 2.00 0.1 1.38 0.2 1.04 Received: 2nd July 1999; Com. 99/1510

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年代:1999

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Determination of organomercury compounds using horseradish peroxidase immobilised on a polyurethane foam Irina A. Veselova and Tatyana N. Shekhovtsova* Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Russian Federation. Fax: +7 095 939 4675; e-mail: shekhov@analyt.chem.msu.ru Polyurethane foam as a novel support for immobilization of horseradish peroxidase has been used for the development of a test technique for the determination of trace organomercury cations (MeHg+, EtHg+, PhHg+) based on their liberating effect on the enzyme inhibited by phenylthiourea in the o-dianisidine oxidation or on their effect on the duration of an induction period in the 3,3',5,5'-tetramethylbenzidine oxidation in the presence of diethyldithiocarbamate.The determination of trace inorganic and organic mercury has an increasing importance in environmental analysis. Organomercury compounds (OMCs) are the most toxic mercury species. Instrumental methods1–4 for the determination of OMCs are highly sensitive and selective, but the majority of them are fairly complicated and require the use of specialised and expensive equipment.Test methods are characterised by simple experimental techniques and, as a rule, require little or no instrumentation. In enzymatic test methods, the advantages of enzyme assay (high sensitivity and selectivity) and immobilised enzymes (simplicity of application and storage) are combined. Recently,5 test methods for the determination of 0.02– 1000 mmol dm–3 of OMCs were developed using horseradish peroxidase (HRP) immobilised in chitosan in the wells of a polystyrene plate and on chromatography paper.At the same time, it has been shown6 that the most promising support for peroxidase immobilization is a polyurethane foam (PUF). The preparation of PUF-immobilised peroxidase retains a constant catalytic activity for longer than 1.5 years, whereas in the case of polystyrene plates and chromatography paper the enzyme preparations are stable for a year and 6 months, respectively.7–8 We have examined the effect of OMC cations (methyl-, ethyl- and phenylmercury) on HRP immobilised in chitosan on a polyurethane foam and developed a new test procedure for the determination of organic mercury.† Determination of OMCs using (i) o-dianisidine oxidation in the presence of phenylthiourea, or (ii) TMB oxidation in the presence of DEDTC, catalysed by PUF-immobilised HRP.The required volumes of solutions of the reaction components were applied sequentially to the same point at the surface of a PUF tablet (diameter of 0.8 cm and thickness of 0.3 cm) with immobilised peroxidase using a micropipette. (i) When o-dianisidine oxidation was used, 12 ml of a 0.1 mol dm–3 potassium hydrogen phthalate buffer (pH 5.0) and 2 ml of 0.1 mol dm–3 phenylthiourea were added to the PUF-immobilised peroxidase.Next, 6 ml of a methyl-, ethylor phenylmercury solution of a required concentration, 6 ml of 2.5 mmol dm–3 o-dianisidine and 6 ml of 5 mmol dm–3 hydrogen peroxide were added sequentially. † Experimental.Horseradish peroxidase (1.11.1.7) from ‘Reanal’ (Hungary) was used (RZ = A403 /A430 = 3.28). The aqueous enzyme solutions were prepared by dissolving the commercial enzyme preparation in a sodium borate buffer (pH 7.0) containing 20 vol% of a 0.1 M sodium nitrate solution to maintain a constant ionic strength. Solutions of the enzyme substrates [o-dianisidine, o-phenylenediamine and 3,3',5,5'-tetramethylbenzidine (TMB)], sulfur-containing organic compounds [phenylthiourea and diethyldithiocarbamate (DEDTC)], MeHgI, EtHgBr and PhHgCl were prepared daily by dissolving accurately weighed amounts (1.0– 3.0±0.2 mg) in ethanol; chemicals from ‘Soyuzreaktiv’ (Russia) were used.The preparation of phenylmercury solutions included preliminary dissolution of an accurately weighed portion of PhHgCl in 3–4 drops of 0.1 M HCl in order to prevent decomposition.The solution obtained was diluted to the required volume with ethanol. Solutions of phenylthiourea, DEDTC and OMCs were stored in the dark. All the solutions were prepared using twice-distilled and demineralised water. Peroxidase was modified and immobilised using water-soluble native chitosan9 and PUF according to the procedure described in ref. 5. (ii) When TMB oxidation was used, 12 ml of a 0.1 mol dm–3 potassium hydrogen phthalate buffer (pH 5.0), 6 ml of 5 mmol dm–3 TMB, 4 ml of 7.5 mmol dm–3 DEDTC, 6 ml of an OMC solution of a required concentration and 6 ml of 5 mmol dm–3 hydrogen peroxide were added sequentially to the PUF-immobilised peroxidase.In both procedures, at the instant when hydrogen peroxide was added, a stopwatch was started, and the time taken for the spot to develop a red (i) or brown (ii) colour was measured. The calibration graph was plotted as the time of appearance of the corresponding colour vs. OMC concentration. Choice of the indicator system. For the development of the test method for determinating OMCs, peroxidase-catalysed reactions of o-dianisidine, o-phenylenediamine and TMB oxidation in the presence of phenylthiourea and DEDTC were used as indicators.Phenylthiourea and DEDTC were introduced in order to enhance the effect of OMCs on the enzymatic processes.7–8,10 The indicator reaction rate was monitored visually by colour changes of the intermediate and final products, presented in Table 1.The most contrasting colour changes on PUF were observed in the cases of o-dianisidine oxidation in the presence of phenylthiourea (blue–green–red) and TMB oxidation in the presence of DEDTC (blue–brown). The colour changes in the o-phenylenediamine oxidation gave poor contrasts in all cases. Thus, the o-dianisidine–H2O2 in the presence of phenylthiourea and TMB–H2O2 in the presence of DEDTC indicator systems seem to be most promising for the development of the test method for determining OMCs.We found that the introduction of an OMC to the indicator reactions with PUF-immobilised peroxidase led to the same effect as in the presence of native peroxidase. Thus, methylaThe colour appearance was monitored visually. Table 1 Colour changes of polyurethane foams in the oxidation of o-dianisidine, o-phenylenediamine and TMB, catalysed by immobilised peroxidase, in the presence of (i) phenylthiourea and (ii) DEDTC.Indicator reaction Colour change (i) (ii) o-Dianisidine–H2O2 blue®green®reda brown®red-brown o-Phenylenediamine–H2O2 pale red®pale blue pale red®pale blue TMB–H2O2 pale blue®grey® colourless blue®brown Table 2 Optimum concentrations of the components of the reactions of (i) o-dianisidine and (ii) TMB oxidation in the presence of PUF-immobilised peroxidase (0.1 mol dm–3 potassium hydrogen phthalate buffer, pH 5.0). Component Optimum concentration/mmol dm–3 (i) (ii) o-Dianisidine 0.4 — TMB — 0.8 H2O2 0.8 0.8 Phenylthiourea 0.2 — DEDTC — 1.25Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) mercury (as well as other OMCs) decreases the inhibiting effect of phenylthiourea on the enzyme catalysing o-dianisidine oxidation. This results in a decrease in the time of the appearance of a red colour of the final product of o-dianisidine oxidation. Thus, methylmercury acts as a liberator of the inhibited immobilised enzyme11 as in the case of native peroxidase.Such a liberating effect can be explained by the interaction between methylmercury and phenylthiourea (as we earlier showed by spectrophotometry). The combined effect of DEDTC and an OMC (methyl-, ethyl- or phenylmercury) results in a decrease in the induction period in comparison with that in the absence of OMCs. The time of the appearance of a brown colour of the final product of TMB oxidation in the presence of DEDTC decreased proportionally to the OMC concentration.Note that the nature of the anion has no influence on the rate of the indicator process. Optimisation of conditions for the determination of OMCs in the presence of phenylthiourea. The OMC effect on the rate of o-dianisidine oxidation in the presence of PUF-immobilised peroxidase was examined under optimum conditions that were chosen by a detailed investigation (Table 2).The optimum concentrations of the indicator reaction components were selected to give a contrasting colour change on PUF after 30–40 s. This period of time is sufficient to measure reliably the inhibiting effect of phenylthiourea and to make the procedure reasonably rapid.The analytical characteristics of the developed procedures are presented in Table 3. Note that, in contrast to the earlier developed procedures for determining OMCs with another solid supports for immobilised peroxidase, it is not necessary to preincubate the enzyme with components of the reaction. Thus, this procedure is more rapid. Optimisation of conditions for the determination of OMCs in the presence of DEDTC.The rates of TMB oxidation catalysed by PUF-immobilised HRP in the presence of DEDTC as functions of the concentrations of TMB, H2O2 and DEDTC were investigated. The rate was characterised by the time of appearance of a brown colour on a PUF tablet. After varying the concentration conditions for the indicator reaction in the presence of DEDTC, optimum concentrations that gave a contrasting colour change on PUF after 60 s were chosen (Table 2).We found that at DEDTC concentrations higher than 100 mmol dm–3 a brown colour did not appear at all. For DEDTC concentrations from 0.75 to 10 mmol dm–3, there is no induction period, and the reaction proceeds with immediate appearance of a blue colour further changed to a brown colour.A DEDTC concentration range of 75–100 mmol dm–3 was chosen as optimum because it led to a maximum induction period. Under the optimum conditions, OMCs decreased the induction period in proportion to their concentration. This fact allowed us to develop a test procedure for the determination of OMCs with the analytical characteristics presented in Table 4.Inorganic mercury(II) does not influence the rate of the indicator reactions in the presence of phenylthiourea and DEDTC. Mercury(II) inhibits the peroxidase activity only in the presence of thiourea.12 Thus, the proposed test procedures for the determination of OMCs are selective for mercury(II). The investigation of the selectivity of the determination of OMCs in the presence of other known effectors of native peroxidase (heavy metals, sulfurcontaining organic compounds) showed that a 100-fold excess of PbII or BiIII interfered with the determination of OMCs at a level of CL using procedure (ii) because of the capability of these cations to interact with DEDTC, changing the duration of the induction period.Sulfur-containing organic compounds (such as acetylthiourea, 1,4-dithiotrietole, 1,2,4-triazolethiole), which are also peroxidase inhibitors (weaker than phenylthiourea), can interfere with the determination of OMCs according to procedure (i) at their 106-fold excesses.The procedure developed was successfully applied to the determination of methylmercury in water of the Kara Sea.13 The use of PUF-immobilised peroxidase allowed us to develop test procedures for the determination of methyl-, ethyl- and phenylmercury cations, which are more sensitive, reproducible and rapid than those with the use of peroxidase immobilised in polystyrene plate wells and on chromatography paper.It should be emphasised that the catalytic activity of the PUF-immobilised enzyme is stable for a much longer time. The procedures are simple, rather selective (without complicated sample preparation), inexpensive and usable for the determination of organomercury compounds in natural water under field conditions.This work was supported in part by the Russian Foundation for Basic Research (grant no. 97-03-33578a). References 1 M. Hemple, H. Hintelman and R. Wilken, Analyst, 1992, 117, 669. 2 S. Corrado, Pittsburg Conference Abstracts, New Orleans, 1992, p. 310. 3 H. Emborg, D. Baxter, M. Sharp and W. Frech, Analyst, 1995, 120, 69. 4 E. Saouter and B. Blattman, Anal. Chem., 1994, 66, 2031. 5 T. N. Shekhovtsova, S. V. Muginova and N. A. Bagirova, Anal. Chim. Acta, 1997, 344, 145. 6 I. A. Veselova and T. N. Shekhovtsova, Anal. Chim. Acta, 1999, 392, 151. 7 T. N. Shekhovtsova, S. V. Chernetskaya, E.B. Nikolskaya and I. F. Dolmanova, J. Anal. Chem., 1994, 49, 778. 8 T. N. Shekhovtsova, S. V. Chernetskaya, N. V. Belkova and I. F. Dolmanova, J. Anal. Chem., 1995, 49, 709. 9 H.-G. Elias, Polymer News, 1977, 3, 217. 10 A. Foster and J. Webber, Adv. Carbohydr. Chem., 1960, 15, 371. 11 N. N. Ugarova, G. D. Rozhkova and I. V. Berezin, Biochem. Biophys. Acta, 1979, 570, 31. 12 I. F. Dolmanova, T. N. Shekhovtsova and V. V. Kutcheryaeva, Talanta, 1987, 34, 201. 13 T. N. Shekhovtsova, S. V. Chernetskaya and I. F. Dolmanova, Int. J. Environ. Anal. Chem., 1998, 69, 191. ay is the time of the appearance of a red colour, x is the OMC concentration (mmol dm–3). bLower limit of analytical concentrations. cCalculated at cl (n = 3). Table 3 Analytical characteristics of the test procedures for determining the OMCs using o-dianisidine oxidation in the presence of phenylthiourea, catalysed by (i) PUF and (ii) paper-immobilized peroxidase5 (higher limit of analytical concentrations is 1 mmol dm–3).OMC Calibration equation r (i) (ii) cl b/mmol dm–3 RSDc (%) cl b/mmol dm–3 RSDc (%) Methylmercury y = –13.5x + 4.5 0.9998 0.008 11 1 23 Ethylmercury y = –13.3x + 3.9 0.9998 0.01 12 11 18 Phenylmercury y = –11.1x + 3.7 0.9998 25 12 12 18 ay is the time of the appearance of a brown colour, x is the OMC concentration (mmol dm–3). bLower limit of analytical concentrations. cCalculated at cl (n = 3). Table 4 Analytical characteristics of the test procedures for determining the OMCs using TMB oxidation in the presence of DEDTC, catalysed by (i) PUF and (ii) paper-immobilized peroxidase5 (higher limit of analytical concentrations is 1 mmol dm–3). OMC Calibration equation r (i) (ii) cl b/mmol dm–3 RSDc (%) cl b/mmol dm–3 RSDc (%) Methylmercury y = –16.9x + 31.3 0.9998 0.01 9 5 30 Ethylmercury y = –7.8x + 27.6 0.9996 1 11 120 26 Phenylmercury y = –6.9x + 30.4 0.9994 75 12 110 23 Received: 12th March 1999; Com. 99/1459

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年代:1999

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) 2-Methyl-2-nitrosopropane as a new regulator of the polymer chain growth Dmitry F. Grishin,* Lyudmila L. Semyonycheva and Elena V. Kolyakina Research Institute for Chemistry, N. I. Lobachevskii Nizhnii Novgorod State University, 603600 Nizhnii Novgorod, Russian Federation. Fax: +7 8312 65 8162; e-mail: grishin@ichem.unn.runnet.ru Aliphatic nitroso compounds are efficient regulators of the radical polymerization of methyl methacrylate through the ‘pseudoliving’ chain mechanism. It is well known1–5 that stable nitroxyl radicals, in particular, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and its analogues, can control the chain growth in the polymerization of styrene and methyl methacrylate (MMA).A significant disadvantage of the regulators is that they effectively influence the growth stage only at temperatures above 373 K.Thus, low-molecular stable radicals cannot be widely used under industrial conditions of polymer synthesis. To control polymer chain growth in the radical polymerization of MMA, we proposed the use of 2-methyl-2-nitrosopropane (MNP), which is traditionally employed as a spin trap and can add active radical centres (including polymer radicals) with the formation of stable nitroxyl spin adducts directly in the reaction system. 2-Methyl-2-nitrosopropane was synthesised by a well-known procedure.6 MMA, azobis(isobutyronitrile) (AIBN) and solvents were purified by standard procedures.7 The physico-chemical constants of the compounds used were consistent with the published data.Samples for polymerization were prepared under a residual pressure of 1.33 Pa, the experimental details were described elsewhere.8 The kinetics of polymerization was monitored by gravimetry, dilatometry and thermography.9 The molecular weight (MW) of the polymer was determined by viscometry10 and gel permeation chromatography using a set of five styrogel columns with pore diameters of 105, 3×104, 104, 103 and 250 Å (Waters, USA).An R-403 differential refractometer (Waters) was used as a detector. Tetrahydrofuran served as an eluent. For the calibration, narrow-disperse polystyrene standards11 were used. The data indicate that, on adding 0.01–0.05 mol% MNP, the initial rate of MMA polymerization decreased only slightly (Table 1).At the same time, this additive caused a noticeable decrease in the autoacceleration process. Moreover, a successive increase in the additive concentration from 0.01 to 0.05 mol% relative to MMA results in a gradual decrease of the polymerization rate at the autoacceleration stage (Figure 1, curves 2–4) and almost comletely eliminates a gel effect which induces a spontaneous increase in the molecular weight and the composition inhomogeneity of polymers.Earlier,12 we proposed the use of N-tert-butyl-a-phenylnitrone for controlling the radical polymerization of acrylic monomers. Note that MNP is a more efficient growth regulator because it actively affects the growth of polymer chains in much lower amounts (0.01–0.05 mol%). The addition of more than 0.1 mol% MNP to a monomer mixture gives rise to a considerable increase in the induction period (Table 1) and to strong inhibition of the overall process.On the basis of the reactivity of nitroso compounds and a mechanism of ‘pseudoliving’ polymerization in the presence of nitroxyl radicals,13 it is reasonable to assume that the controlled propagation of a macromolecular chain results from the interaction of MNP with polymeric (oligomeric) radicals to form stable nitroxyl radicals (A·): where ~Pn · is a macroradical containing n monomeric units.This is the cause of an induction period observed in dilatometric studies. Nitroxyl spin adducts (A·) interact with growing radicals with the generation of labile terminal groups: The lability of the chemical bond [~Pn· – – ·A] is caused by the stability of the the nitroxyl radical [A·].This stability is associated with electron density redistribution between oxygen and nitrogen atoms and also with steric hindrances from the tert-butyl group of nitroxyl. It is well-known that radical reactions are very sensitive to steric environments. The uniform reinitiation as a result of reverse reaction (2) leads to the occurrence of a ‘pseudoliving’ polymerization mechanism.In this case, the chain growth proceeds via sequential insertion of the monomer at the labile bond [~Pn· – – ·A]: 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 100 200 300 400 500 600 t/min dP/dT (% min–1) 1 2 3 4 Figure 1 Differential kinetic curves of the polymerization of methyl methacrylate in the presence of MNP at 338 K; iniiator, [AIBN] = 0.1 mol%, MNP concentrations (mol%): (1) 0, (2) 0.01, (3) 0.02, (4) 0.05.~Pn · + But–N=O ~Pn–N–O· But (1) A· ~Pn · + ·A [~Pn · – – ·A] (2) 4 3 2 1 0 0 20 40 60 80 100 MW×10–6 Conversion (%) 1 2 3 4 Figure 2 Molecular weight (MW) of poly(methyl methacrylate) as a function of conversion: (1)–(3), viscosity-average MW; (4) number-average MW; initiator, [AIBN] = 0.1 mol%.MNP concentrations (mol%): (1) 0, (2) 0.01, (3) and (4) 0.02.Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Another explanation of the polymerization mechanism of MMA in the presence of MNP can be given in terms of the secondary catalytic inhibition of the polymerization of vinyl monomers by nitroxyl radicals, which was considered in detail by Smirnov.14 In order to examine this mechanism under particular conditions, the molecular-weight distribution of the samples prepared in the presence of various MNP concentrations and the molecular weights of polymeric products as functions of the degree of conversion were studied.We found that the chromatograms of poly(methyl methacrylate) (PMMA) samples are unimodal, and the mode is regularly shifted towards the high-molecular region with increasing time of polymerization.This indicates that the polymerization is accompanied by a continuous rise of the average MW of the polymer. In addition, the numberaverage and viscosity-average molecular weights are linear functions of the conversion up to high degrees of conversion (Figure 2). This demonstrates that the number of propagating chains is constant during the overall process. The MW data indicate that almost all polymeric chains are able to reinitiate and to grow via the ‘pseudoliving’ chain mechanism up to high degrees of conversion. The coefficient of polydispersity (the ratio between the weight-average and number-average molecular weights) of the polymer varies to some extent in the course of the process (Table 1).An insignificant increase in the coefficient of polydispersity (higher than 1.5) with conversion can be associated with bimolecular chain termination, which lead to formation of an amount of a ‘dead polymer’ simultaneously with the ‘living’ mechanism of polymerization. Thus, MNP as a potential source of stable radicals directly participates in the stage of polymer chain growth and controls the rate of the process and the molecular-weight characteristics of PMMA in a relatively ‘soft’ temperature range (323–338 K).An important feature of this growth regulator is that, in contrast with other regulators,1–5 stable radicals capable to control the polymeric chain growth are formed directly in the course of polymerization by the interaction of the polymeric macroradicals with the additive.This additive is more efficient as a polymerization modifier than TEMPO and other stable radicals. In controlling the polymeric chain propagation, MNP slightly decreases the rate of polymerization and hence can outperform other regulators of radical polymerization.2–5,14 This work was supported by the Russain Foundation for Basic Research (grant no. 99-03-33346) and the Competitive Centre of Fundamental Science. References 1 E. Rizzardo, D. Solomon and P. Cacioli, European Patent Appl., EP135280, 1985 (Chem. Abstr., 1985, 102, 221335g). 2 C. J. Hawker and J. L. Hendrick, Macromolecules, 1995, 28, 2993. 3 C. J. Hawker, G. G. Barclay, A. Orellana, J. Dao and W. Devonport, Macromolecules, 1996, 29, 5245. 4 E. Youshida, J. Polym. Sci., Part A: Polym. Chem., 1996, 34, 2937. 5 R. P. N. Veregin, P. G. Odell, L. M. Michalak and M. K. Georges, Macromolecules, 1996, 29, 3346. 6 S. Terabe and S. Konska, J. Chem. Soc., Perkin Trans. 2, 1972, 2163. 7 Analytical Chemistry of Polymers, ed. G. M. Kline, Wiley, New York, 1962, p. 384. 8 D. F. Grishin, L. L. Semyonycheva and E.V. Kolyakina, Dokl. Ross. Akad. Nauk, 1998, 362, 634 [Dokl. Chem. (Engl. Transl.), 1998, 199]. 9 Uchebnik po khimii i fizike polimerov (Manual in Chemistry and Physics of Polymers), ed. V. F. Kurenkov, Khimiya, Moscow, 1990, p. 310 (in Russian). 10 S. R. Rafikov, S. A. Pavlov and I. I. Tverdokhlebova, Metody opredeleniya molekulyarnykh vesov i polidispersnosti vysokomolekulyarnykh soedinenii (Methods for Determination of Molecular Weights and Polydispersity of High-Molecular Compounds), Khimiya, Moscow, 1963, p. 357 (in Russian). 11 S. Moris, J. Liq. Chromatogr., 1990, 13, 1719. 12 D. F. Grishin, L. L. Semyonycheva and E. V. Kolyakina, Vysokomol. Soedin., Ser. A, 1999, 41, 609 [Polym. Sci. (Engl. Transl.), 1999, 41, 401]. 13 E. Yoshida and T. Fujll, J. Polym. Sci., Part A: Polym. Chem., 1998, 269. 14 B. F. Smirnov, Vysokomol. Soedin., Ser. A, 1990, 32, 583 [Polym. Sci. USSR (Engl. Transl.), 1990, 32, 524]. [~Pn · – – ·A] + CH2=C–Me [~P·n + 1 – – ·A] C(O)OMe (3) Table 1 Characteristics of the polymerization of MMA and the polymer formed in the presence of MNP; initiator, [AIBN] = 0.1 mol%, T = 323 K. Entry MNP concentration (mol%) Induction period/ min Initial rate/ 10–4 mol dm–3 s–1 Conversion (%) Coefficient of polydispersity 1 0 0 1.22 11.8 2.0 2 0.01 0 0.94 — — 3 0.02 ~25 0.59 3.6 1.6 4 0.02 ~25 0.59 5.4 1.8 5 0.02 ~25 0.59 14.7 2.2 6 0.02 ~25 0.59 71.7 2.2 7 0.05 ~50 0.55 — — 8 0.1 ~180 0.37 — — Received: 26th April 1999; Com. 99/1484

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年代:1999

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Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Reactions of resorcinol with substituted 3,4-dihydro-2(1H)-pyrimidinethiones Sergei I. Filimonov Department of Organic Chemistry, Yaroslavl State Technical University, 150023 Yaroslavl, Russian Federation. Fax: +7 0852 44 0729; e-mail: z55@yaroslavl.ru Acid-catalysed alkylation of resorcinol by substituted tetrahydropyrimidinethiones has been examined.The interaction between pyrimidinethiones and phenolic compounds was first examined by Zigeuner et al.1–2 It was found that pyrimidinethiones formed a product of addition at the 6-position of the pyrimidine ring upon boiling with a tenfold excess of 2,6-dimethylphenol in methanol with concentrated hydrochloric acid as a catalyst. Moreover, Zigeuner et al.1 noted that, when the reaction was performed with 2,4-xylenol under the same conditions, the main reaction product was 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane. In this study, the reaction of resorcinol addition to pyrimidinethiones 1 has been examined.It is well known3 that rearrangement products, corresponding 1,3-thiazines and aminodihydro- 2(1H)-pyridinethiones, can be formed when the reaction is performed under the above conditions1 (heating with a strong mineral acid).Thermal reactions (zinc chloride catalyst, temperature up to 140 °C) were unsuccessful (the yields were low). Thus, the reaction conditions were changed. The interaction of compounds 1 with resorcinol was examined at temperatures from 40 °C to the boiling temperatures of nonpolar solvents (chloroform, trichloroethylene and toluene) using sulfonic acids as catalysts. The products were separated as a precipitate or oil in 45–90% yields.† It is likely that the reaction is reversible, and complete alkylation can be performed not always even with a large excess of resorcinol.As a rule, a precipitate (oil) separated from the reaction mixture contained up to 80% of the target product, 10–20% of resorcinol and 5–15% of the starting pyrimidinethione (according to HPLC data).† IR spectra were measured on a Bruker IFS-88 spectrometer in the range 700–4000 cm–1 using suspensions of substances in Vaseline oil. 1H NMR spectra of test compounds were recorded on a Bruker AM-300 spectrometer at 300 MHz using 3–5% solutions in [2H6]DMSO.The chemical shifts of protons were measured with reference to an internal standard of HMDS (0.055 ppm). Mass spectra were measured on a MX-1321 mass spectrometer with direct sample injection at 100–150 °C with an ionisation energy of 70 eV. Reversed-phase high-performance liquid chromatography was performed on a Perkin-Elmer instrument (mobile phase: acetonitrile–water, 70:30; stationary phase: C-18).Starting compounds 1 were synthesised according to published procedures. 1,2 The reaction time of the resorcinol alkylation by compounds 1 depends on the structure of the substituent R. The reaction rate depends on the capability of the substituent R to stabilise the intermediate carbocation. Compounds 1 in which R = H exhibited the highest rate of the reaction with resorcinol.The reaction rate dramatically decreased in the order R = H, Me, Ph and C6H4Me-p. In the case of R = C6H4NO2-p, the reaction does almost not proceed under the specified conditions. The effect of the substituent R3 is not so evident; the reaction time was insignificantly shortened in the order Me, Et and Ph, C6H4OMe-p. Compound 2k (R2 = 2-Fur) is an exception, probably, because of its low solubility.The catalyst amount has almost no effect on the reaction time; an amount equal to 10% of the weight of the pyrimidine-thione reactant is sufficient. With higher concentrations, the amount of by-products increases thus decreasing the yield and making the purification difficult. Methanesulfonic acid was tested as a catalyst; however, it did not exhibit considerable advantages.To decide on a solvent, its capability of dissolving the starting pyrimidinethione should be taken into account. For active compounds with R = H, the reaction proceeded with approximately equal ease in toluene, chloroform or trichloroethylene. In contrast, for compounds with R = Ph, the target product was almost not formed in toluene, and the reaction time was halved when the reaction was performed in trichloroethylene. In this case, the reaction temperature exerted a considerable effect. The IR spectra of resorcinol-substituted pyrimidinethiones did not exhibit bands due to double bonds in the pyrimidine ring in the region 1700–1630 cm–1. Not always clearly defined signals (as a rule, as doublets) appear in the regions 3400–3250 and 1000–900 cm–1, which are indicative of the presence of hydroxyl groups in the molecule.The 1H NMR spectra of resorcinol-substituted pyrimidinethiones 2‡ exhibit a spin–spin interaction constant of 13–14 Hz, which is typical of the gem-protons 5-He/5-Ha. Mixtures of rotational isomers (50:50) were detected for compounds with unsymmetrical substituents R (R = m-ClC6H4 and m-CF3C6H4); in this case, the signals of OH, 5-Ha and 6-Me were split into doublets.On this basis, the most downfield signal (split) of a hydroxyl proton can be attributed to the OH group in the a-position with respect to the pyrimidine ring, and the most upfield signal should be attributed to the 6-Me group. N N R3 R S H R1 R2 HO OH HO OH N N R3 R S H R1 R2 H+ D 1a–l 2a–l aR1= R2 = R3 = Me, R = H b R1 = R2 = R3 = R =Me c R1 = R2 = R3 = Me, R = Ph d R1 = R2 = R3 = Me, R = C6H4Me-p e R1 = R2 = R3 = Me, R = C6H4OMe-p f R1 = R2 = R3 = Me, R = C6H4Cl-m g R1 = R2 = R3 = Me, R = C6H4CF3-m h R1 = R = H, R2 = Ph, R3 = Me i R1 = R = H, R2 = R3 = Ph j R1 = R = H, R2 = Ph, R3 = C6H4OMe-p k R1 = R = H, R2 = 2-Fur, R3 = C6H4OMe-p l R1 = R = H, R2 = Ph, R3 = Et aHPLC (retention time).bThe reaction time for syntheses in chloroform. Table 1 Physico-chemical properties of compounds 2. Empirical formula MW mp/°C R.T./ mina Reaction time/hb Yield (%) 2a C13H18N2O2S 266.36 211–213 0.86 1 90 2b C14H20N2O2S 280.4 207–209 0.82 1.5 86 2c C19H22N2O2S 342.46 210–212 0.99 10 74 2d C20H24N2O2S 356.48 225–226 1.07 18 65 2e C20H24N2O3S 372.48 217–218 0.96 6 60 2f C19H21ClN2O2S 376 212–214 0.97 8 72 2g C20H21F3N2O2S 410.45 221–222 1.02 10 76 2h C17H18N2O2S 312.4 210–212 0.90 4 53 2i C22H20N2O2S 376.47 240–242 0.96 3 55 2j C23H22N2O3S 406.50 188–190 0.86 2 71 2k C21H20N2O4S 396.46 193–195 1.00 4 50 2l C18H20N2O2S 328.43 145–147 0.83 1.5 74Mendeleev Communications Electronic Version, Issue 6, 1999 (pp. 213–255) Compounds 2h–2l were isolated as mixtures of the stereoisomers different in the spatial orientation of resorcinol at carbon in the 6-position.The arrangement of the R2 substituent is always equatorial, as evidenced by a large spin–spin interaction constant of 11–12 Hz of vicinal protons 4-Ha/5-Ha equal to 11–12 Hz. The ratio between the isomers depended on the separation procedure; however, isomers with more upfield chemical shifts of hydroxyl proton signals were predominant.‡ General procedure for the synthesis of substituted tetrahydro-6-(2,4- dihydroxyphenyl)-2(1H)-pyrimidinethiones 2. A suspension containing a pyrimidinethione (0.01 mol), resorcinol (0.015 mol) and 0.1 g of toluenesulfonic acid in 20–30 ml of chloroform was boiled for 1–20 h until the formation of a precipitate (oil), which was separated and purified as follows: (i) the precipitate (oil) was dissolved in isopropanol (acetone) on heating; next, the solution was cooled and poured into water with intense stirring; (ii) the oil or solid precipitate was purified by crystallization from acetone–chloroform or acetone–benzene. 2a: 1H NMR, d: 9.11 (s, 1H, OH), 8.78 (s, 1H, OH), 7.83 (s, 1H, NH), 7.68 (s, 1H NH), 6.88 (d, 1H, H12 Rz, J 8.5 Hz), 6.23 (d, 1H, H9 Rz, J 1.8 Hz), 6.16 (dd, 1H, H11 Rz, J 8.5 and 1.8 Hz), 3.0 (d, 1H, 5-He, J 13.3 Hz), 1.53 (d, 1H, 5-Ha, J 13.3 Hz), 1.55 (s, 3H, 4-Mee), 1.19 (s, 3H, 4-Mea), 0.63 (s, 3H, 6-Me).IR, n/cm–1: 3358, 3290, 3180, 1614, 1604, 981, 940. 2b: 1H NMR, d: 9.46 (s, 1H, OH), 9.17 (s, 1H, OH), 9.89 (s 1H, NH), 6.4 (d, 1H, H11 Rz, J 8.0 Hz), 6.32 (s, 1H, H9 Rz), 6.18 (d, 1H, H12 Rz, J 8.0 Hz), 3.3 (s, 3H, NMe), 2.89 (d, 1H, 5-He, J 13.5 Hz), 1.73 (d, 1H, 5-Ha, J 13.5 Hz), 1.68 (s, 3H, 4-Mee), 1.12 (s, 3H, 4-Mea), 0.58 (s, 3H, 6-Me).IR, n/cm–1: 3330, 3200, 1598, 1520, 1500, 975. 2c: 1H NMR, d: 9.28 (s, 1H, OH), 8.98 (s, 1H, OH), 8.09 (s, 1H, NH), 7.7–7.3 (m, 6H, HAr), 6.26 (d, 1H, H9 Rz, J 1.5 Hz), 6.24 (dd, 1H, H11 Rz, J 8.5 and 1.5 Hz), 3.12 (d, 1H, 5-He, J 13.4 Hz), 1.88 (d, 1H, 5-Ha, J 13.4 Hz), 1.40 (s, 3H, 4-Mee), 1.37 (s, 3H, 4-Mea), 0.63 (s, 3H, 6-Me).IR, n/cm–1: 3350, 3320, 975. 2d: 1H NMR, d: 9.55 (s, 1H, OH), 9.35 (s, 1H, OH), 8.2 (s, 1H, NH), 7.2–7.0 (m, 6H, HAr), 6.32 (s, 1H, H9 Rz), 6.23 (d, 1H, H11 Rz, J 8 Hz), 3.12 (d, 1H, 5-He, J 13.8 Hz), 2.37 (s, 3H, MeAr), 2.0 (d, 1H, 5-Ha, J 13.8 Hz), 1.37 (s, 3H, 4-Me), 1.30 (s, 3H, 4-Me), 0.63 (s, 3H, 6-Me).IR, n/cm–1: 3384, 3377, 3190, 1619, 1606, 980, 961. MS, m/z: 356 (50) [M+], 341, 246, 231, 217, 205, 191, 175, 149, 107, 91, 58, 40. 2e: 1H NMR, d: 9.43 (s, 1H, OH), 9.13 (s, 1H, OH), 8.12 (s, 1H, NH), 7.05 (m, 3H, HAr), 6.8 (dd, 2H, HAr, J 9 Hz,) 6.32 (s, 1H, HRz), 6.27 (d, 1H, HRz, J 8.3 Hz), 3.73 (s, 3H, OMe), 2.0 (d, 1H, 5-He, J 13.5 Hz), 1.9 (d, 1H, 5-Ha, J 13.5 Hz), 1.27 (s, 3H, 4-Me), 1.23 (s, 3H, 4-Me), 0.58 (s, 3H, 6-Me).IR, n/cm–1: 3500, 3350, 1619, 1599, 1523, 1500, 1160, 990, 920. 2f: 1H NMR, d: 9.55 (s, 1H, OH), 9.25 (s, 1H, OH), 8.38 (s, 1H, NH), 7.3 (m, 3H, HAr), 7.05 (m, 2H, HAr) 6.32 (m, 2H, HRz), 3.02 (d, 1H, 5-He, J 14.0 Hz) , 1.95 (t, 1H, 5-Ha, J 14.0 Hz), 1.32 (s, 3H, 4-Me), 1.26 (s, 3H, 4-Me), 0.6 (d, 3H, 6-Me).IR, n/cm–1: 3300, 3200, 980, 940. 2g: 1H NMR, d: 9.35 (s, 1H, OH), 9.03 (s, 1H, OH), 8.36 (s, 1H, NH), 7.7–7.3 (m, 4H, HAr), 7.04 (dd, H, H12 Rz, J 8.0 Hz), 6.32 (s, H, H9 Rz), 6.28 (d, H, H12 Rz, J 8.0 Hz), 3.1 (d, 1H, 5-He, J 13.9 Hz), 1.92 (t, 1H, 5-Ha, J 13.9 Hz), 1.3 (s, 6H, 4-Me), 0.6 (s, 3H, 6-Me), a mixture of rotational isomers with OH, Ar and NH doublets.IR, n/cm–1: 3260, 3030, 1605, 1595, 970, 915. MS, m/z: 412 (1.5) [M+], 411 (5.9), 285 (5.6), 261 (6.1), 259 (15.9), 203 (99), 191 (25.9), 182 (22), 175 (100), 161 (20), 150 (23), 145 (22), 135 (14.9). References 1 G. Zigeuner, A. Frank, H. Dujmovits and W. Adam, Monatsh. Chem., 1970, 101, 1415. 2 G. Zigeuner, W. B. Lintschinger and F.Wode, Monatsh. Chem., 1975, 106, 1219. 3 G. Zigeuner, W. B. Lintschinger, A. Fuchsgruber and K. Kollmann, Monatsh. Chem., 1976, 107, 155. Received: 16th April 1999; Com. 99/1477 2i (a mixture of two diastereoisomers in the ratio ~60:40): 1H NMR, d: major isomer, 9.38 (s, 1H, OH), 9.10 (s, 1H, OH), 8.20 (1H, NH), 7.76 (s, 1H, NH), 7.4–7.1 (m, 11H, HAr + HRz), 6.38 (d, 1H, HRz, J 8.0 Hz), 6.32 (s, 1H, HRz), 4.4 (dd, 1H, 4-H, J 11.5 and 2.9 Hz), 3.1 (dd, 1H, 5-H, J 13.5 Hz and 2.9 Hz), 2.1 (dd, 1H, 5-H, J 13.5 and 11.5 Hz); minor isomer, 9.72 (s, 1H, OH), 8.93 (s 1H, OH), 8.28 (s, 1H, NH), 7.53 (s, 1H, NH), 6.22 (d, 1H, HRz), 6.15 (d, 1H, HRz), 3.84 (dd, 1H, 4-H), 2.64 (dd, 1H, 5-H), 2.38 (t, 1H, 5-H). IR, n/cm–1: 3415, 3300, 3200, 1615, 1600, 978. 2h (a mixture of two diastereoisomers in the ratio ~85:15): 1H NMR, d: major isomer, 9.47 (s, 1H, OH), 9.18 (s, 1H, OH), 8.4 (s, 1H, NH), 8.0 (s, 1H, NH), 7.40–7.15 (m, 5H, HAr), 6.9 (d, 1H, H12 Rz, J 8.0 Hz), 6.35 (s, 1H, H9 Rz), 6.23 (d, 1H, H11 Rz, J 8.0 Hz), 3.78 (dd, 1H, 4-H, J 11.5 and 3.0 Hz), 2.98 (dd, 1H, 5-He, J 12.6 and 3.0 Hz), 1.58 (dd, 1H, 5-Ha, J 12.6 and 11.5 Hz), 1.53 (s, 3H, 6-Me); minor isomer, 9.8 (s, 1H, OH), 9.12 (s 1H, OH), 8.23 (s, 1H, NH), 8.12 (s, 1H, NH), 6.22 (d, 1H, HRz), 6.15 (d, 1H, HRz), 4.23 (dd, 1H, 4-H), 2.9 (dd, 1H, 5-H), 1.7 (t, 1H, 5-H).IR, n/cm–1: 3350, 3120, 1615, 1595, 975. 2j (a mixture of two diastereoisomers in the ratio ~60:40): 1H NMR, d: major isomer, 9.7 (s, 1H, OH), 9.08 (s, 1H, OH), 8.28 (s, 1H, NH), 8.15 (s, 1H, NH), 7.4–6.15 (m, 12H, HAr + HRz), 3.88 (dd, 1H, 4-H, J 11.8 and 3.0 Hz), 3.76 (s, 3H, OMe), 2.6 (dd, 1H, 5-H, J 13.2 and 3.0 Hz), 2.35 (dd, 1H, 5-H, J 13.2 and 11.8 Hz); minor isomer, 9.32 (s, 1H, OH), 9.1 (s, 1H, OH), 8.25 (s, 1H, NH), 7.68 (s, 1H, NH), 4.32 (dd, 1H, 4H, J 11.8 and 3.0 Hz), 3.72 (s, 3H, OMe), 3.12 (dd, 1H, 5-H, J 13.2 and 3.0 Hz), 2.1 (dd, 1H, 5-H, J 13.2 and 11.8 Hz).IR, n/cm–1: 3250, 3380, 1603, 1540, 1040, 978. MS, m/z: 406 [M+], 396, 330, 296, 253, 236, 219, 177, 165, 148, 134, 110, 104, 82, 76, 53, 39. 2k (a mixture of two diastereoisomers in the ratio ~95:5): 1H NMR, d: 9.32 (s, 1H, OH), 9.09 (s, 1H, OH), 8.16 (1H, NH), 7.69 (s, 1H, NH), 7.45 (s, 1H, 3-HFu), 7.13 (m, 3H, HAr + HFu), 6.78 (d, 2H, HAr, J 9.5 Hz), 6.3 (m, 4H, HRz + HFu), 4.35 (dd, 1H, 4-H, J 11.1 and 3.0 Hz), 3.72 (s, 3H, OMe), 3.15 (dd, 1H, 5-H, J 13.9 and 3.0 Hz), 2.38 (dd, 1H, 5-H, J 13.9 and 11.1 Hz). IR, n/cm–1: 3440, 3250, 1618, 1598, 1036, 1018, 982, 930. 2l (a mixture of two diastereoisomers in the ratio ~90:10): 1H NMR, d: 9.25 (s, 1H, OH), 8.95 (s, 1H, OH), 7.75 (s, 1H, NH), 7.7 (s, 1H, NH), 7.4–7.15 (m, 5H, HAr), 6.9 (d, 1H, H12 Rz), 6.35 (d, 1H, H9 Rz), 6.23 (dd, 1H, H5 Rz), 3.9 (dd, 1H, 4-H, J 11.6 and 3.0 Hz), 2.9 (dd, 1H, 5-H, J 12.6 and 3.0 Hz), 1.78 (dd, 1H, 5-H, J 11.6 and 12.6 Hz), 2.03 (m, 1H, CH2), 1.87 (m, 1H, CH2), 0.78 (t, 3H, Me).

ISSN:0959-9436     

出版商:RSC    

年代:1999

数据来源: RSC