摘要:

The intramolecular alkylation of several bromo- and epoxy-2-methylcyclopentenones,18–23and33, are described. In all cases, except33, alkylative cyclization occurs at the γ′ position to the conjoint ring systems25–31. The "blocked" bromide33(γ′ geminal dimethyl substituent) cyclizes to the fused ring hydrindenones35and/or34depending upon conditions. Enolateanion generation from 3-ethyl-2-methyl-2-cyclopentenone (36) with various bases (KH, LDA, Et3N) is described and the anion populations determined by quenching with chlorotrimethylsilane to afford the enol ethers39–41. The intramolecular alkylations are discussed.

ISSN:0008-4042    

DOI:10.1139/v84-138

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Details of the synthesis, physical properties, and molecular structures of 4,4-dimethyl-2,5,5-triphenyl-1,3-dioxa-4-azonia-2-bora-5-boratacyclopentane,4, and 4,4,5,5-tetramethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-boratacyclopentane,5, are reported. Crystals of4are triclinic,a = 9.841(2),b = 14.722(3),c = 6.6701(12) Å, α = 86.79(1), β = 102.95(1), γ = 93.89(1)°,Z = 2, space group; and those of5are monoclinic,a = 14.9164(12),b = 6.4732(3),c = 18.2248(15) Å, β = 117.263(3)°,Z = 4, space groupCc. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to finalRvalues of 0.032 and 0.035 for 1456 and 1649 observed reflections, respectively. Molecules of4contain non-planar BOBON rings with an unusually long N(sp3)—B(sp3) distance of 1.728(3) Å and in5there is a long N(sp3)—C(sp3) bond of 1.591(3) Å. These structural features are ascribed to steric hindrance.

ISSN:0008-4042    

DOI:10.1139/v84-139

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The title compound was prepared by the reaction of 8-methyl-6,6-diphenyl-5,7-dioxa-8-azonia-6-borata-6,7-dihydro-5H-benzocycloheptene (1) with phenylboronic acid. Crystals of 3a-methyl-2,4,9a-triphenyl-1,2,3a,4,9,9a-hexahydro-1,3,9-trioxa-3a-azonia-2-bora-9a-boratacyclopenta[b]naphthalene are monoclinic,a = 11.8548(4),b = 22.7837(4),c = 8.5457(3) Å, β = 106.952(2)°,Z = 4, space groupP21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures toR = 0.040 andRw = 0.047 for 2970 reflections withI ≥ 3σ(I). The molecule was found to be a formal addition product between1and PhBO which had undergone a 1,4-shift of a phenyl group from boron to carbon. The backbone of the molecule consists of a folded system of three fused rings. The structure contains the longest known B(sp3)—N(sp3) bond, 1.759(2) Å.

ISSN:0008-4042    

DOI:10.1139/v84-140

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The enthalpy of NaI solution was determined in water mixtures with methanol, ethanol, propanol, and isopropanol in the entire range of mixed-solvent concentration at 288.15 and 308.15 K, and in water mixtures withs-butanol andtert-butanol in the range of 0–5 mol% alcohol at 308.15 K. The dependence ofon solvent composition was studied. The enthalpic pair interaction coefficientshENfor NaI–alcohol in water and NaI–water in alcohols were determined, and the effect of temperature onhENvalues in the systems under study was analyzed.

ISSN:0008-4042    

DOI:10.1139/v84-141

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The crystal structure of Pt(CH3CN)2Cl2has been determined twice independently. The compound is thecisisomer. It crystallizes in the monoclinicP21/cspace group,a = 6.660(3) [6.668(4)],b = 12.500(7) [12.519(8)],c = 10.277(6) [10.308(5)] Å, β = 105.42(4) [105.41(4)]°,V = 824.7(8) [829.6(9)] Å3. The structure was refined by full-matrix least-squares analysis to a conventionalRfactor of 0.054 [0.058] andRw = 0.053 [0.057] for 1578 [1226] observed reflections. The coordination is square planar with bond lengths (Pt—N = 1.98(1), 1.98(1) [1.95(2), 1.99(2)] Å and Pt—Cl = 2.264(4), 2.263(3) [2.270(6), 2.277(5)] Å) slightly shorter than normal. The N—C bonds are 1.10(2), 1.11(2) [1. 11(3), 1.16(2)] Å. The C—CH3bonds are shorter than normal single bonds (1.48(2), 1.45(2) [1.49(3), 1.45(3)] Å and the N—C—C framework is almost linear. Infrared (4000–100 cm−1) and Raman (4000–60 cm−1) spectra of the crystalline solid have been measured and assigned; the vibrational spectra confirm thecisstructure. A rough molecular force constant analysis based on a cw-planar C2v. skeleton (ignoring H atoms) was carried out and aided in the vibrational assignments. Thev(Pt—Cl) bands occur at 362 and 333 cm−1; thev(Pt—N) bands occur at 463 and 408 cm−1, and show strong coupling with the PtNC deformations.

ISSN:0008-4042    

DOI:10.1139/v84-142

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Structure determination of theO-trimethylsilyl,O-acetyl, andO-isopropylidene derivatives of some hexosuloses, pentosuloses, and one tetrosulose, as well as their methyl glycosides and 1,1-dimethyl acetals has been achieved by gas chromatography – mass spectrometry.By study based on the qualitative and quantitative differences in the 36 derivatives obtained, and their analogues prepared from tetradeuterio methanol and/or hexadeuterio acetone, and comparison with results reported in the literature, criteria for the unambiguous determination of the structural grouping are proposed. The relative abundance of each compound when the osulose forms more than one isomeric derivative in the same reaction, as well as chromatographic data for the isolated products, are reported.

ISSN:0008-4042    

DOI:10.1139/v84-143

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The densities and heat capacities of various alkali hydroxides were measured in water with a vibrating tube densimeter and a flow microcalorimeter in the temperature range 4 to 55 °C. The concentration ranges investigated were respectively: 0.04 to 3.8 mol kg−1for LiOH, 0.02 to 10.9 mol kg−1for NaOH, and 0.02 to 15.5 mol kg−1for KOH. The partial molar volumesand heat capacitieswere calculated from the least-squares fit of the apparent molar quantitiesas a function of molalities. From the temperature dependence of these functions the apparent molar expansibilitiesandwere derived. The ultrasonic velocities were also measured for the dilute solutions of NaOH at 25 °C, and can be used to calculate the standard partial molar compressibilities and isochoric heat capacities. The present data were compared with literature values. The general trends as a function of concentration are similar to those of other 1:1 electrolytes even though the deviations from the Debye–Hückel theory are larger.

ISSN:0008-4042    

DOI:10.1139/v84-144

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The reaction between 2,3,4,6-tetra-O-benzyl-1,5-di-O-mesyl-D-glucitol and cesium propionate in dimethylformamide at 100 °C leads to an almost quantitative conversion into 3,4,6-tri-O-benzyl-1-O-propionyl-2,5-anhydro-L-iditol. Closure of the anhydro ring appears to entail anchimeric assistance by the 2-O-benzyl substituent in an SN2 displacement at C-5, leading to an inversion at the latter position. Probable contributors to the marked regio- and stereoselectivity observed for the reaction are a unique property of cesium propionate as compared with other carboxylate salts, large differences in rate between competing reactions, and a geometry highly favorable to an intramolecular displacement process. Conformational properties of 2,5-anhydro-L-iditol, as well as of isomeric 2,5-anhydro-D-mannitol, are described, based on nmr evidence.

ISSN:0008-4042    

DOI:10.1139/v84-145

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The preparation, magnetic and thermal properties, electronic and infrared spectra, and molecular structure of poly-bis(μ-di-n-hexylphosphinato)copper(II) are described. Crystals of the compound are triclinic,a = 9.800(3),b = 12.336(6),c = 13.352(8) Å, α = 88.53(3), β = 74.02(4), γ = 82.33(3)°,Z = 2, space group. The structure was solved by Patterson and Fourier syntheses and was refined by full-matrix least-squares procedures toR = 0.045 andRw = 0.056 for 3095 reflections withI ≥ 3σ(I). The crystal structure of Cu[(n-C6H13)2PO2]2consists of well-separated infinite chains of centro-symmetric spiro-fused eight-membered rings propagating along the crystallographicaaxis.The magnetic susceptibility of Cu[(n-C6H13)2PO2]2was studied over the temperature range 4.2 to 300 K. The compound shows ferromagnetic behaviour and the data have been successfully analyzed according to the isotropic Heisenberg model for linear chains withg = 2.16 andJ = 2.58 cm−1. For comparison, the magnetic susceptibilities of Cu[(C2H5)2PO2]2and Cu[(n-C4H9)2PO2]2have also been measured over the range 4.2 to 300 K. The butyl derivative shows ferromagnetic exchange withg = 2.16 andJ = 2.22 cm−1while the ethyl derivative is antiferromagnetic withg = 2.19 and −J = 1.27 cm−1. The structural details of all three compounds are examined in the light of the differing magnetic properties.

ISSN:0008-4042    

DOI:10.1139/v84-146

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The abstraction of hydrogen/deuterium from CH3CHDCl by ground state chlorine atoms produced photolytically from Cl2has been investigated at temperatures betwen 280 and 368 K. The relative rates for the internal competitionare found to conform to an Arrhenius rate law:These data, taken together with the external competition results for the C2H5Cl/CH3CHDCl system, in conjunction with the competitive results using CH4as a primary reference, have yielded the rate constants (cm3s−1):The relatively weak primary kinetic isotope effect,kH/kD, decreases with increasing temperature from 1,855at 280 K to 1.66 at 365 K. The results are compared with those obtained based on the BEBO method. While both the trend and the magnitude of the kinetic isotope effect are satisfactorily predicted, the activation energy is not.

ISSN:0008-4042    

DOI:10.1139/v84-147

出版商:NRC Research Press    

年代:1984

数据来源: NRC