CONFORMATIONAL STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. IV. ELECTRONIC INTERACTION IN 2-THIASUBSTITUTED CARBONYL SYSTEMS. ω-ETHYLTHIO-p-SUBSTITUTED ACETOPHENONES

Abstract

The carbonyl stretching frequencies and the apparent molar absorptivities are reported for some ω-ethylthio-p-substituted acetophenones and for the corresponding unsubstituted acetophenones. In the ω-ethylthio-series the solvent effect indicates the presence of the cis/gauche rotational isomerism, being the gauche rotamer predominant in the whole series (ca. 90%). In the ω-ethylthioacetophenones, on going from electron-attracting to electron-donating substituents, the progressive increase in the carbonyl cis shifts (Δν_c) is attributed to the increasing Field Effect between C[dbnd]O and C[sbnd]S dipoles, and the progressive decrease in the carbonyl gauche shifts (Δν_g) is due to the deacreasing contribution of the hyperconjugative interaction between π_CO and σ_c[sbnd]s orbitals. The U.V. spectra of the ω-ethylthioacetophenones display a n → π?_CO band which is bathochromically shifted in relation to the corresponding acetophenones, indicating the occurrence of the hyperconjugative interaction between π?_CO and σ?_c[sbnd]s orbitals in the excited state. ¹³C NMR data for the methylene group of ω-ethylthioacetophenones, compared to those for some ω-haloacetophenones,^2,3 suggest that in the fundamental state besides the hyperconjugative interaction, there is also the occurrence of charge transfer from π_CO to 3d_(S) orbitals.     

KINETIC STUDIES ON THE ACID-CATALYZED PUMMERER REACTION OF α-(METHYLSULFINY)ACETOPHENONES

Abstract

The kinetic behavior of the acid-catalyzed Pummerer reaction of α-(methylsulfinyl)acetophenones in dilute hydrochloric acid has been studied in detail. The kinetic data were analyzed in the light of correlations between the reaction rates and acidity functions, activation parameters, solvent isotope effects, polar effects of substituents, etc. Moreover, ¹⁸O-tracer experiments were also carried out using acid media containing H₂ ¹⁸O. Based on these observations, a plausible mechanism for this reaction has been discussed.     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS 69.A NOVEL SYNTHESIS OF 5-SUBSTITUTED 3-(1''''-DIETHOXYPHOSPHORYLALKYL)-2-ISOXAZOLINES

Additions of diethyl phosphite to α-nitroalkenes followed by the introduction of trimethylchlorosilane and an activated alkene, gave the corresponding title compounds via regioselective 1,3-dipolar cycloaddition in moderate yield.     

~(11)B NMR AND QUANTUM CHEMISTRY STUDIES OF BORATRANE COMPOUNDS

The ~(11)B chemical shifts of boratrane compounds were measured. Quantum chemistry calculations of some of the compounds wore carried out using the CNDO/2 method. Both experimental and calculated results confirmed the existence of the B←N dative bonds in boratranes. The exporimental results indicate that the ~(11)B chemical shifts are influenced by the size of the rings, the characteristics of substituents and steric factors. The calculated results indicate that the strengths of the B←N dative bonds in boratranes are about half of that of a purely "covalent two-electron bond" and therefore, the dative bonds B←N are stronger than those of Si←N in the analogous silatranes, and the boratranes are more stable than silatranes.     

OXIDATION OF α-METHYL OR α-METHYLENE GROUPS IN CARBONYL COMPOUNDS WITH AMMONIUM CHLOROCHROMATE

This paper reports a new method for oxidizing the α-methyl orα-methylene groups in carbonyl compounds into 1,2-dicarbonyl compoundsby ammonium chlorochromate(ACC).     

CONFORMATIONAL INVESTIGATIONS OF 5-SUBSTITUTED ISOPROPYLIDENE MALONATES 1. STRUCTURE OF 5-(α-PHENYLETHYL)-2,2-DIMETHYL-l,3-DIOXAN-4,6-DIONE

<正> , Mr=248.28, monoclinic, P2!/n, a=ll.394(4), b=5.770(1), c=20.534(6) &, (3=106.09(2)? V=1297.1(4) X3, Z=4, 1^=1.265, Dx=l.271 Mgm'3, y(Moka)=0.87cm~1, F(000)=527.94, 295K. The structure was solved by direct methods and refined to R=0.057 for 1984 observed Moka reflections. The 1,3-dioxan-4,6-dione ring shows a twist-boat conformation with the a-phenylethyl group occupying a bow position. , . .     

STUDIES ON ORGANOMETALLIC COMPOUNDS OF TITANIUM,ZIRCONIUM AND HAFNIUM——THE CRYSTAL AND MOLECULAR STRUCTURES OF OXO-BRIDGED TETRAKIS(CYCLOPENTADIENYL)BIS (o.TOLYL)AND TETRAKIS(METYLCYCLOPEN-TADIENYL) BIS(p-TOLYL)BINUCLEATED ZIRCONIUM COMPOUNDS

This paper reports the crystal and molecular structures of tetrakis (cyclopentadienyl) bis(o-tolyl)-μ-oxo-dizirconium [dimer (Ⅰ)] and tetrakis (methylcyclopentadienyl) bis (p-tolyl)-μ-oxo-dizirconium [dimer (II)]. Both of them belong to monoclinic system and possess the same spacegroup C_2~5h- 2_1/a. The cell dimer (Ⅰ) containing four molecules is defined by a=19.122A,b=16.319A, c = 9.296A, β= 92°1′; the cell dimer (Ⅱ) containing two molecules is defined bya = 20.076A, b = 8.205A, c = 10.016A, β= 104°41′. The important difference of molecular configurations between the two dimers lies in thatthe dimer (Ⅰ) has no symmetry center and its Zn-O-Zr oxo-bridge presents a slightly bentconfiguration while the dimer (Ⅱ) takes the oxgen atom as a symmetry center and its oxo-bridge present linear linkage. In accordance with the above-mentioned molecular configuration, steric effect and elec-tronic structure have been further discussed.     

STUDIES ON BORON COMPOUNDS (Ⅱ)——SYNTHESIS AND PROPERTIES OF BORON CONTAINING BIS(π-ARENE)IRON(Ⅱ)COMPOUNDS

Thirteen bis(π-arene)iron(Ⅱ) compounds were synthesized.They are [Ar FelB12H12 (Ar=C6H6 MeC6H5;EtC6H5;n-PrC6H5;t-Pr-C6H5 and These compounds have all been identified by elemental analysis and IR spectra,some of them by MS and H NMR.The thermal behavior of these compounds has been investigated by DTA-TG method and IR spectroscopy,and their thermal stability was described.     

CONVERSION OF ACETALS AND KETALS TO CARBONYL COMPOUNDS PROMOTED BY ZrCl_4-NaBH_4

In our study on the chemistry of ZrCl_4-NaBH_4,we have found that aldehydes and ketonescan be regenerated from acetals and ketals at 30℃ in Et_2O in high yield The reaction mechanismwas discussed.     

MICELLIZATION STUDIES OF DODECYL BENZENESULFONIC ACID AND ITS INTERACTION WITH POLYVINYLPYRROLIDONE

Dodecyl benzenesulfonic acid (DBSA) surfactant was used in the present study to find the effect of concentration on its electrical conductance in solution from 293-323K above and below the critical micelle concentration (CMC). The micellization parameters i.e. degree of counter ion binding (β), aggregation number (n) and number of counter ion micelle(m) were measured. The interaction of DBSA with polyvinylpyrrolidone (PVP) was also studied at 293K throughconductance and surface tension measure ments. A number of important parameters i.e. critical aggregation concentration (CAC), Gibb‘s free energy (△G) and binding ratio (R) were determined and the effect of NaCl on the CAC and polymer saturation point (PSP) was also investigated.     

SYNTHESIS AND ELECTRONIC SPECTRA OF RUTNENIUM(Ⅱ)-1,1''''-BIISOQUINOLINE COMPLEXES

l,l'-biisoquinoline can coordinate with ruthenfum(Ⅱ) to form a new series of mononuclear complexes and the electronic absorption of these complexes were measured and reasonably assigned.     

CONFORMATIONAL CHARACTERISTICS OF POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID)

A full-relaxation optimization of molecule and the Dreiding force field are employed toobtain the geometry parameters and the conformational energy surfaces of meso or racemicdyad of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA). Three differentcarbonyl-bond orientations of side-groups resulted in the differences in depth of potentialwells in their energetic contours for a meso or a racemic dyad. These discrepancies areinterpreted as a result of various fine structures corresponding to grid search conformationsas well as thereby different interactions. The analysis on the most stable conformationsof PMAA confirmed that the ester groups are nearly perpendicular to the plane definedby the two adjacent skeletal bonds but may possibly change their relative orientations tomeet the requirement of lower energy during the conformational state transition. For eachpolyme, two global energy maps of a meso and a racemic dyad were finally constructedfrom the superposition of energy data for the three kinds of side-group orientations by theBoltzmann factors. From an ensemble average, the proposed scheme with three rotationalisomeric states (RIS) allowed us to access the experimentally unperturbed dimensions ofPAA chain via the configurational statistical mechanics. Although the calculation wasbased on the short-range, local interactions, it was interested to note that the experimentalcharacteristic ratios just fell within the range calculated for atactic chains.     

PHOTOPHYSICS STUDIES OF ORGANIC COMPOUNDS——NANOSECOND LASER PHOTOLYSIS AND TRANSIENT ABSORPTION SPECTRA STUDIES OF PYRENE-AROMATIC AMINES

Nanosecond time-resolved transient absorption spectra of pyrene-triphenylamine, pyrenediphenylamine, pyrene-N, N-dibenzylaniline systems in various solvents have been investigated. In nonpolar solvent, pyrene-triphenylamine exciplex and pyrene-N, N-dibenzylaniline exciplex were observed directly. In acetonitrile, the pyrene anion radical, triphenylamine and diphenylamine cation radicals were detected. On the basis of the present experimental facts, the mechanism of fluorescence quenching processes of pyrene in polar and nonpolar solvents has been established.     

STUDIES ON ORGANO-MOLYBDENUM AND TUNGSTEN COMPOUNDS(Ⅲ)——CATALYTIC POLYMERIZATION OF ACETYLENE BY M-O-C BOND-CONTAINING COMPLEXES OF Mo AND W

Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymerization of monosubstituted acetylene.The catalytic mechanism has been preliminarily discussed.It is suggested that the active species be metal-car-bene.In our previous publications we reported the synthesis of some new Fischer's molybdenum and tungsten-carbene complexes and catalytic activity for alkyne polymerization.The results show that the activity of Fischer's molybdenum-carbene is higher than that of tungsten.The catalytic polymerization of alkyne by M-σ-c bond-containing complexes of molybdenum and tungsten has not been reported yet in literature.Therefore,four M-σ-C bondontaining complexes of molybdenum and tungsten were synthesized by using the method reported in the literature,and catalyst polymerization of alkyne by these complexes was examined.     

NMR STUDIES ON THE WEAK INTERACTION OF FOUR-MONONUCLEOTIDES WITH TRYPTAMIDE AND LEUCINAMIDE

NMR spectroscopy analysis was introduced to investigate the weak interaction of four 5'—mononucleotides with tryptamide and leucinamide. Assuming a 1∶1 complex formation, the association constants were determined by nonlinear regression analysis. The association affinity of 4 mononucleotides with tryptamide decreased in the order: G>A>C>U, indicating that purine bases stack more strongly with tryptamide than pyrimidine bases. But with leucinamide the affinity decreases in the order: G>C>A=U, suggesting an amino acid—anticodonic preferential interaction. The implication of the present data to the origin of genetic code was briefly discussed.     

STUDIES ON THE DEMETHYLATION-ALKYLATION REACTION OF ACETOPHENONES VIA 2-(1,3-DITHIAN-2-YLIDENE)-1-ARYLETHENONES

2-(1,3-dithian-2-ylidene)-1-arylethenones3 Via chemoselective 1,2-addition with methyl,ethyl,phenyl,allyl,and benzyl Grignard reagents afforded thecorresponding alcohols(4).Catalyzing by silica gel,thealcohols 4 were converted to the aryl.ketones(5).Theentire process represent a demethylation— alkylationreaction of acetophenones.The mechanism of reaction areproposed and the structure requirement for the conversionof the alcohols(4)was discussed.     

STUDIES ON TRANSITION-METAL PERHALOPHENYL COMPOUNDS.VI.CRYSTAL STRUCTURE OF TRANS-BROMO-BIS(METHYLDIPHENYLPHOSPHINE) (σ-PENTABROMOPHENYL)NICKEL(II)

<正> M= 1010.62, D24-P212121, a=11.654(3), b=15.812(9), c=18.556(8) A, V=3419.5A3, Z=4, Dc=1.963 g·cm-3. Final R=0.066 for 2187 reflections. The central nickel(II) atom of the title compound is in slightly distorted square-planar coordination.     

STUDIES ON ORGANOMETALLIC COMPOUNDS OF TITANIUM,ZIRCONIUM AND HAFNIUM——THE SYNTHESES AND PROPERTIES OF BIS (CYCLOPENTADIENYL) AND BIS (METHYLCYCLOPENTADIENYL) DI(ARYL)-METAL DERIVATIVES

Aryllithium reacts with Cp_2MCl_2 and Cp'_2 MCl_2 (C_p=η~5-C_5H_5, C_P′=η~5-CH_3C_5H_4:M=Ti, Zr, Hf) respectively to prepare a series of new bis (cyclopentadienyl), bis (methy-lcyclopentadienyl) diaryl derivatives of titanium, zirconium and hafnium. The hydrolysicreaction of these organometallic compounds are studied, the derivatives of zirconium andhafnium can be easily hydrolyzed with the exception of that of titanium. They react withhydrogen chloride, acetyl chloride, bromine and haloacids to form the respective bis(cyclo-pentadionyl) dihalides of these metals. The NMR and IR spectra were discussed in regardto the structure of (η~5--CH_3C_5H_4)_2 MAr_2 and (η~5--CH_3C_5H_4)_2 MX_2.     

MOLECULAR STRUCTURE AND SPECTRAL STUDIES OF Ni(ENAC)

<正> C12H20N2O2Ni,Mr = 283. 02, orthorhombic, Pbn21 ,a = 10. 269 (2), b = 12. 182(2),c= 10. 348(1) A,V=1294.5 A3,Z = 4,DC = 1. 452 g/cm3,MoKa radia-tion(λ= 0.71073 A ) ,μ= 14. 96 cm-1, F (000) = 600, R = 0. 058 for 1131 reflections. The Ni (Ⅱ ) ion in This molecule has a square planar configuration. The three chelate rings formed by Ni atom and ENAC2- are coplanar with the plane of NiO2N2. Ultra violet-visible and IR spectra are in agreement with the crystal structure data.     

STUDIES ON ORGANOMETALLIC COMPOUNDS OF TITANIUM,ZIRCONIUM AND HAFNIUM TITANIUM, ZIRCONIUM AND HAFNIUM——SYNTHESES AND PROPERTIES OF BIS (CYCLOPENTADIENYL) DI-(ARYLOXY) DERIVATIVES

The dichlorides of bis(cyclopentadienyl) or bis(methylcyclopentadienyl) titanium, zircon-ium and hafnium reacting with phenol or substituted phenols in the presence of base give aseries of new aryloxymetal derivatives. The activities of chlorine atoms in the dichlorides ofbis(cyclopentadienyl)titanium, zirconium and hafnium molecules towards phenols are compared.The influence upon HNMR of the cyclopentadienyl ring due to the electronegativities of themetals and the substituents on the phenyl rings, as well as the number and position of thesubstituents are discussed.