The structure of copolymers of vinyl cyclohexane with styrene

Copolymerization of vinyl cyclohexane (monomer-1) with styrene was investigated in the presence of the stereospecific complex catalyst TiCl₃ + Al(iso-C₄H₉)₃. Monomer reactivity ratios were r₁ = 0·177 ± 0·051 and r₂ = 2·117 ± 0·370. The monomer unit distributions in the copolymers were estimated by comparison of the i.r.-spectra of copolymers and the isotactic homopolymers using absorption bands at 565 and 1084 cm^?1 which correspond to the vibrations of styrene blocks containing ? 5 styrene units and the band at 985 cm^?1 characterizing polystyrene crystallinity. The data indicate the tendency towards alternation in the copolymerization. Analysis of the experimental and literature data led to the conclusion that distribution of the units in copolymers of vinyl cyclohexane with α-olefins is determined by the nature of the α-olefin. The following activity series is proposed for α-olefins in their copolymerization with vinyl cyclohexane in the presence of catalytic systems based on titanium salts and organo-aluminium compounds: propylene >; 4-methylpentene-1 >; styrene >; 3-methylbutene-1 ～ vinyl cyclohexane.     

一个取代的三环1,5-苯并二氮杂卓的晶体结构和构 象分析2

用单晶X射线衍射方法测定了6-苯甲酰基-5-(邻氯苯基)-2,3,3a,4,5,6-六氢-3a-苯基-(1,2,3-三乙酸乙酯基)-1H-吡咯啉[1,2-a][1,5-]苯并二氮杂卓的晶体结构。单斜晶系,空间群P2~1/c,a=1.3235(5)nm,b=1.7142(6)nm,c=1.6204(6)nm,β=100.49(3)°,Z=4,最终偏离因子R=0.062,R~w=0.075。晶体结构测定结果表明分子中二氮杂卓七元环采取船式构象,动力学模拟退火计算结果的最低能量构象为椅式,两者的能量差不大,表明这种船式<－>椅式的变化是非常容易发生的。     

Crystal and molecular structure of salvicin — A diterpenoid acid of the clerodane series

The spatial structure of the diterpenoid salvicin has been determined by x-ray structural analysis. The trans-linkage of rings A/B proposed previously has been confirmed. This indicates that rings A and B in related diterpenoids — salvin and salvinin — also have the trans-linkage.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 63–68, January–February, 1988.     

Crystal structure of a fuse cyclohexane with an axial t-butyl group: 8β-t-butyl-trans-decahydroquinoline

8β-t-Butyl-trans-decahydroquinoline picrate crystallizes a double chair with an axial t-butyl group. Except for a 16.2° torsion of the t-butyl group way from the staggered conformation, the molecule displays only minor conformation deformations.     

Energetic analyses of chair and boat conformations of maleimide substituted cyclohexane derivatives

An analysis of the conformational preferences of two maleimide substituted cyclohexane derivatives proposed as scaffolds for HIV-1 fusion inhibitors is presented. Hybrid Low Mode-Monte Carlo (1:1) conformational searches using seven different force fields were performed in combination with the GBSA(water) solvent model. Low energy structures identified in this way were subjected to geometry optimization on the B3LYP/6-31G** surface. Solvent effects were included in the quantum calculation using the self-consistent reaction field model for water. Quantum results indicate that the 1,3,5-maleimide functionalized 1,3,5-methyl cyclohexane is more stable in the boat conformation, whereas 1,3,5-maleimide functionalized cyclohexane adopts the expected chair conformation with equatorial arms. None of the force fields studied was able to predict the unexpected preference for the boat conformation of 1,3,5-maleimide functionalized 1,3,5-methyl cyclohexane. Comparison of low energy and experimental structures was also performed.     

Reaction of phenyldichlorophosphine with diacetyl

Conclusions Phenyldichlorophosphine reacts with diacetyl to form 5-methyl-2-phenyl-4-chloro-2-oxo-1,2-oxaphosphol-4-ene. Hydrolysis of this compound gives phenyl-(-chloro--oxo)butylphosphinic acid, and alcoholysis gives the ester of this acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 466–468, February, 1969.     

Synthesis and properties of aromatic polyamides containing the cyclohexane structure

1,1-Bis[4-(4-carboxyphenoxy)phenyl]cyclohexane (III) and 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane (V) were prepared in two main steps starting from the aromatic nucleophilic substitution of p-fluorobenzonitrile and p-chloronitrobenzene, respectively, with 1,1-bis(4-hydroxyphenyl)cyclohexane in the presence of potassium carbonate in N,N-dimethylformamide (DMF). Using triphenyl phosphite and pyridine as condensing agents, two series of polyamides with cyclohexylidene cardo groups were directly polycondensated from dicarboxylic acid III with various aromatic diamines or from diamine V with various aromatic dicarboxylic acids in an N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The polyamides exhibited inherent viscosities in the range of 0.45 to 1.78 dL/g. Almost all of the polymers were readily soluble in polar aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc) and could afford transparent, flexible, and tough films by solution casting. The glass transition temperatures (T_g) of these aromatic polyamides were in the range of 180–243°C by DSC, and the 10% weight loss temperatures in nitrogen and air were all above 450°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3575–3583, 1999     

Reaction of 1,1,2,2-tetrafluoropropanal with phenylhydrazine

Conclusions The reaction of 1,1,2,2-tetrafluoropropanal with phenylhydrazine gave difluoromethyl-glyoxal bis(phenylhydrazone) and mesoxaldehyde tris(phenylhydrazone); reaction with phenylhydrazine acetate in aqueous medium gave 1-phenyl-4-phenylazopyrazole. The dehydrofluorination of perfluoroethylglyoxal bis(phenylhydrazone led to 1-phenyl-4-phenylazo-5-trifluoro-methylpyrazole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1912–1916, August, 1977.The authors express their gratitude to P. V. Petrovskii for taking and interpreting the¹³C NMR spectra.     

Kinetics of symmetric electron exchange reaction in series of substituted nitrobenzenes: Influence of reactant structure

Kinetic data on symmetric electron exchange in substituted nitrobenzenes have been obtained by means of ESR. The logarithm of the electron exchange rate constant varies linearly with the square of the constant of hyperfine splitting on the nitrogen atom of the nitro group. On the basis of the results obtained, it is concluded tentatively that solvation of the nitro group plays a decisive role in the kinetics of symmetric electron exchange in this series of compounds.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 6, pp. 688–693, November–December, 1989.     

Comparative basicities of substituted pyridines and electronegativity series for substituents in the pyridine series

Relationships between basicity of the pyridine ring and the nature and position of substituents are found. Comparative electronegativity series are constructed for substituents (, , and ) in the pyridine series. In isolated cases transmission of an effect from the position by a M effect is found.     

Synthesis of substituted oxazolidinones from compounds of the ethylene series

The reaction of N-bromocarbamates with ethylene compounds was investigated, and the high structural specificity of this reaction was demonstrated. The structures of the (-bromocarbamates obtained were confirmed by their IR and PMR spectra. When they are heated to 602-13D°C, they are readily cyclized to the corresponding oxazolidinones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1628–1630, December, 1979.Original article submitted December 11, 1978.     

Tautomerism of a series of substituted 9-acridinethiones

A quantitative estimation of thione-thiol tautomerism in a series of substituted 9-acridinethiones was performed by methods of IR, UV, and mass spectrometry as a function of the aggregated state, temperature, and solvent. It was shown that the thione form predominates in the crystal and gas phase; the position of the equilibrium is ambiguous in solutions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1519–1524, November, 1984.     

Reactions of trialkylborines with hydrazine and phenylhydrazine

Summary With hydrazine and phenylhydrazine trialkylborines form complex compounds which decompose when heated with formation, respectively, of 1,2-bisdialkylborinohydrazines and 1-dialkylborino-2-phenylhydrazines.