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71.
72.
H. R. Hudson R. W. Matthews O. O. Shode Gy. Keglevich I. Petneházy L. Toke 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Trialkyl phosphites are known to react with α-halogenoketones to yield β-ketophosphonates (Arbuzov product) or vinyl phosphates (Perkow product) according to coniiitions.1 α-Hydroxyphosphonate may be formed in addition, in prcltic media.2 We have now shown that none of these products is formed in the presence of silver perchlorate (in benzene sclutim); nor could we detect the ketophosphonium perchlorate reported previously. Phosphorus-31 nmr showed the formation of trimethyl phosphate and tetramethyl pyrophosphate as the exclusive phosphorus-containing products. The sequence of possible reaction is complex and the overall stoichiometry may vary somewhat according to the rate and order of rixing. Trialkyl phosphate could be formed by elimination of alkyne from vinyloxyphosphonium intermediate produced together with silver iodine in first stage of the interaction. Pyrophosphate formation would then result from nucleophilic attack of trimethyl phosphate on the trimethoxy(1-nethylvinyloxy)phosphoniun ion, which may be formed as a reactive intermediate. Evidence for formation of methyl perchlorate in the final dealkylation of the quasiphosphonium intermediate is provided by proton nmr spectroscopy and by the formation of the N-methylquino-linium salt on addition of quinoline. No change in the 31P nmr spectrum occurs at this stage. Other by-products of the main reactions include the dehalogenated ketone (acetone from iodoacetone or acetnphenone from α-iodoacetophenone). 相似文献
73.
In this paper a proposal is put forward for the calculation of the shearing factor NS linked to the well known, demagnetization coefficient ND, from the data of a sheared saturation loop, obtained by a non-toroidal, open circuit hysteresis measurement. Following that, the paper illustrates the way to recover the real static loop data from an open circuit, measured data. The proposal is based on the hyperbolic model. The proposed method was illustrated on the tests carried out on two closed and open toroidal samples, mimicking the demagnetization effect of the open circuit VSM measurement, made of NO Fe–Si electrical steel sheets. These test results, presented here, agree very well with the calculated results, based on the hyperbolic modeling. 相似文献
74.
Gy. Keglevich I. Petnehazy L. Tuke 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract The ring enlargement of ready available phospholenes by dichlorocarbene addition to the double bond and subsequent opening of the cyclopropane ring is discussed. Adductcs of phospholene wih dichlorocarbene (2)can be synthetised under liquid-liquid phase transfer circumstances. The simplest bray to open the cyclopropane ring in the adducts is thermal transformation giving the two regioisomers of the appropriate dihydrophosphorin (3). Electrophilic reagents can also be used for -the opening of the cyclopropane ring. On heating with silver nitrate in water or in alcohols the adducts are transformed to the -two rcgioisomers of the hydroxy- or the alkoxy -tetrahydrophosphorins, respectively (4, Y=H, CH3 C2H5) In the reaction of adducts with mercury acetate-acetic acid the corresponding acetoxy-derivatives (4, Y=CH3CO) are formed. The Friedl Crofts reaction of the adducts with benzene iii the presence of aluminium trichloride yields diarylated product. 相似文献
75.
DIHALOCARBENE ADDITION TO ARYLSUBSTTTUTED VINYL PHOSPHATES UNDER PHASE TRANSFER CATALYTIC CONDITIONS
Imre Petneházy György Keglevich László Tőke 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):77-82
Abstract Dihalocarbene addition to aryl-substituted vinyl phosphates was carried out both in solid-liquid and in liquid-liquid two phase systems. The dihalocyclopropane adducts of vinyl phosphates could be obtained in better yield using dihalocarbenes generated by the latter method and no hydrolysis of the vinyl phosphate and of the adduct occurred under these circumstances. Eighteen new vinyl phosphate-dihalocarbene adducts were synthetized and characterized. 相似文献
76.
I. Petneházy Zs. M. Jászay Gy. Keglevich L. Toke 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Reaction of trialkyl phosphites 1 with α,β-unsaturated oxo-compounds 2 gives oxaphospholenes 3 or/and two types of Arbuzov products, γ-keto-phosphonates 4 and alkyl-enol-ethers 5. 相似文献
77.
Forced ideal carbocationic copolymerization of isobutylene and isoprene has been achieved by continuous addition of monomer mixtures of different compositions to cumyl chloride/TiCl4 charges at -50°C. The overall rate of copolymerization could be kept equal to that of addition rate with up to 10 mol% isoprene in the mixed monomer feed. In this monomer concentration range the composition of the copolymer was identical to that of the feeds. At higher diene concentrations in the feed, chain transfer to monomer and other side reactions (intramolecular cyclization, gel formation) could not be completely avoided. The number-average molecular weight of the copolymers increased almost linearly with the amount of consumed monomers at 10 mol% isoprene concentrations in the feed (i.e., in the quasiliving range). According to 1H-NMR and 13C-NMR spectroscopy, the products are random copolymers. 相似文献
78.
Reaction of aryl aldehydes with Meldrum's acid 2 in the presence of formic acid and triethylamine gives 5-arylmethyl Meldrum's acid derivatives 4 at room temperature, whereas at 80–100°C 3-arylpropanoic acids 5 are formed. 相似文献
79.
Dr. Györgyi Váradi Prof. Gábor K. Tóth Dr. Zoltán Kele Dr. László Galgóczy Ádám Fizil Prof. Gyula Batta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12684-12692
The folding of disulfide proteins is of considerable interest because knowledge of this may influence our present understanding of protein folding. However, sometimes even the disulfide pattern cannot be unequivocally determined by the available experimental techniques. For example, the structures of a few small antifungal proteins (PAF, AFP) have been disclosed recently using NMR spectroscopy but with some ambiguity in the actual disulfide pattern. For this reason, we carried out the chemical synthesis of PAF. Probing different approaches, the oxidative folding of the synthetic linear PAF yielded a folded protein that has identical structure and antifungal activity as the native PAF. In contrast, unfolded linear PAF was inactive, a result that may have implications concerning its redox state in the mode of action. 相似文献
80.
The effect of the fullerene C60 branching center on the structure and conformation of star-shaped polystyrenes with different arm lengths at equal concentrations in deuterotoluene (c = 1 g/dL) is studied by the method of small-angle neutron scattering. The analysis of neutron scattering for linear PS precursors and stars (the molecular masses of arms are ~7 × 103 and ~4 × 104) shows that the stars have ~6 arms that form a dense excluded-volume zone around a core inaccessible to other macromolecules. In low-molecular-mass stars (the molecular mass of the arm is ~7 × 103), strengthening of the static rigidity of arms is observed; as a result, the size of arms increases relative to the size of free PS chains in a good solvent. At a greater length of arms (M ~ 4 × 104), their individual properties are weakly pronounced in the correlation spectrum of the arm because of the interpenetration of arms, thereby demonstrating similarity in the structures of stars and their linear analogs. The mechanism controlling the effect of fullerene C60 on the conformations of stars via solvent structuring by fullerene is discussed. 相似文献