摘要:

Grignard addition of phenylmagnesium bromide to 3,5-O-benzylidene-1-deoxy-D-erythro-2-pentulose (1) affordsC-phenyl branched-chain pentitols having exclusively either theD-arabino(2) orD-ribo(5) stereochemistry according to the mode of substitution of1. In order to determine the chirality of these products conclusively, the crystal and molecular structure of the unsubstituted pentitol6(from2) has been determined. Crystals of 1-deoxy-2-C-phenyl-D-arabinitol (6; C11H16O4) are orthorhombic, space groupP212121, with cell dimensionsa = 8.9420(6),b = 18.910(1),c = 6.4263(6) Å, andZ = 4. The structure was solved by multi-solution direct methods and refined to a final discrepancy index of 5.6%. The molecule has an extended, planar zigzag conformation with the phenyl ring nearly perpendicular to this plane. Compound6forms one intramolecular (between 2-OH and O-4) and three intermolecular hydrogen bonds. Palladium-catalyzed hydrogenolysis of the 2-phenylcarbamate of2results in deoxygenation of the benzylic center with complete-inversion of configuration, as established by crystal-structure determination of the product7. Crystals of 2(S)-4-O-acetyl-3,5-O-benzylidene-1,2-dideoxy-2-C-phenyl-D-erytro-pentitol (7; C20H22O4) are monoclinic, space groupC2, with cell dimensionsa = 19.102(1),b = 6.1925(5),c = 16.098(1) Å, β = 108.325(9)°, andZ = 4. The structure was solved by multi-solution direct methods and refined to a final discrepancy index of 5.9%. The molecule has an almost ideal planar, zigzag backbone conformation which incorporates the 1,3-dioxane ring. Comparison of the conformation observed in the crystal with that calculated from proton–proton coupling constants shows good agreement

ISSN:0008-4042    

DOI:10.1139/v78-478

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Cd(HSal)2is extracted from aqueous solutions inton-butanol, but not into non-hydroxylic solvents (such as benzene and chloroform) at pH 4.5 to 6.0. Addition of N bases, which have no effect alone, causes extraction into the latter solvents, apparently by displacement of coordinated water, giving Cd(HSal)2•2B. This synergistic effect varies with B (β-picoline > pyridine > quinoline). Formation and distribution constants are given for the experimental conditions.

ISSN:0008-4042    

DOI:10.1139/v78-479

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The compound S7NSN(CH3)2has been prepared by the reaction of S7NH with S[N(CH3)2]2. Crystals are orthorhombic witha = 12.412(4),b = 23.894(6),c = 8.132(2) Å,Z = 8, space groupPbca. The structure was refined to a final agreement indexR1of 0.051 for 1721 observed reflections. The structure of S[N(C6H11)2] was also determined for comparison. The crystals are monoclinic witha = 13.74(2),b = 6.196(8),c = 13.74(2) Å, (β = 91.26(8)°,Z = 2, space groupI2. The structure was refined to a final agreement index,R1of 0.052 for 1024 observed reflections.

ISSN:0008-4042    

DOI:10.1139/v78-480

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Rate constants for the reactions O(3P) + HX → OH + X (X = Br, I) have been determined by a phase shift technique. Oxygen atoms were generated by modulated mercury photosensitized decomposition of nitrous oxide, and were monitored by the chemiluminescence from the reaction with nitric oxide. Over the temperature interval 298–554 K, the rate constants are satisfactorily represented by the Arrhenius expressionskO+HBr = (8.09 ± 0.86) × 109exp (−3.59 ± 0.08)/RTandkO+HI = (2.82 ± 0.27) × 1010exp (−1.99 ± 0.07)/RT, where the units are ℓ mol−1s−1and kcal mol−1. The indicated uncertainties are one standard deviation. The results of bond energy–bond order calculations, incorporating recently proposed modifications, are discusse

ISSN:0008-4042    

DOI:10.1139/v78-481

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The standard enthalpy of transfer of trimethyldecylammonium bromide, tetramethylammonium bromide, methyl and decylsodium sulfate have been determined from water to water + acetone mixtures from calorimetric measurements at 298.15 K. The standard entropy function has been calculated using standard Gibbs free energy of transfer data for the same compounds. It is shown that the standard enthalpy and entropy of transfer of a n-nonylhydrocarbon chain attached to the sulfate or to the trimethylammonium groups are quite different whereas the standard Gibbs free energy functions are practically equal in the mixed solvents. It is concluded that the sign of the charge on the ionic groups is responsible for this behaviour and that the influence of this effect extends to a large number of solvent molecules. It is suggested that a similar effect may contribute to the standard enthalpy of so called reference ions: e.g. tetraphenylboron ion casting some doubt on the reliability of these extrathermodynamic approaches at least in mixed solvents, as far as the standard enthalpy function is concerned.

ISSN:0008-4042    

DOI:10.1139/v78-482

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The Raman spectra of [SbCl4+][Sb2Cl2F9−], [SbCl4+][Sb2F11−], [AsCl4+][SbF6−], and SbCl4F(NbF5)xare reported. The spectra of all compounds except the last are interpreted in terms of a tetrahedral cation with weak association between the cation and anion. The spectra of the adduct found between SbCl4F and NbF5are interpreted in terms of polymeric fluorine bridged arrangements.

ISSN:0008-4042    

DOI:10.1139/v78-483

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Measurements of the penetration of porous substrates (porous glasses) by non-sorbing macromolecules (dextrans) have yielded penetration curves that relate the degree of penetration to molecular size. Combinations of well-characterized polymer fractions with a series of uniformly porous glasses have demonstrated that, in agreement with the theory, the penetration is dependent only on the relative size of the molecule and the pore. Several models differing in the methods of characterizing the sizes of the pores and solute molecules have been compared. The predictions of the shape of the penetration curves are similar for most models and are in similar agreement with the experimental data.

ISSN:0008-4042    

DOI:10.1139/v78-484

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Complex formation between pentachlorophenol and acetone and acetone-d6in carbon tetrachloride solution has been studied in both the hydroxyl and carbonyl stretching regions of the infrared spectrum. Factor analysis of the digitized spectra indicates three absorbing components for each set of solutions in the hydroxyl stretching region. Concentration studies revealed roughly linear relationships between the areas of the 'free' ν(OH) band and both of the resolved complex bands, suggesting that two different 1:1 complexes occur in CCl4solution. In the ν(CO) region only one band due to complex formation was detected. Equilibrium constants for the isotopically different complexes at about 30 °C are reported. In the hydroxyl stretching region, band resolution was also carried out using four components which gave a better fit to the observed spectrum. A set of equilibrium constants were then obtained. However, considerable difficulties were met in the calculations and in the interpretation of these results, so that the three band, two complex model is preferred.

ISSN:0008-4042    

DOI:10.1139/v78-485

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The amino-alcohols HOC(CF3)2CH2CH(CH3)NH(CH2)3NHCH(CH3)CH2C(CF3)2OH and HOC(CF3)2CH2CH(CH3)NH(CH2)3NH(CH2)3NHCH(CH3)CH2C(CF3)2OH have been prepared by reduction of the corresponding imino-alcohols coordinated to, e.g., Cu2+, by use of LiAlH4. The products are capable of acting as polydentate, dinegative, ligands (following ionization of the fluorinated alcohol groups) and the second compound gives stable, neutral, complexes of Co2+, Ni2+, and Cu2+in which the metal atom is five-coordinate.

ISSN:0008-4042    

DOI:10.1139/v78-486

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The kinetics of bromination of the 1,2-dihydro-1,3-dimethyl-2-oxopyrimidinium cation (Q+) in aqueous media (pH 0–5) have been studied using the stopped-flow method. At the higher acidities (pH < 2) the results are consistent with rate determining attack by bromine upon the pseudobase (QOH), whereas at low acidities (pH > 4) it appears that pseudobase formation is rate determining. The change occurs because at high acidity the reversal of the pseudobase QOH to the cation is fast relative to bromine attack, whereas at low acidity the converse is true. Results obtained at intermediate acidities (pH 2–4) are consistent with this interpretation.A separate kinetic study of pseudobase formation (and decomposition) yielded rate constants in good agreement with those derived from the bromination study.

ISSN:0008-4042    

DOI:10.1139/v78-487

出版商:NRC Research Press    

年代:1978

数据来源: NRC