摘要:

We have made measurements with a flow calorimeter leading to apparent molal heat capacities of aqueous solutions of NaCl, HCl, KBr, KCl, KOH, NaBr, HBr, and NaOH at 298 K. Results have been used to derive apparent molal heat capacities of these electrolytes at infinite dilution and thence ΔCp0 = −215.2 ± 4 J K−1mol−1for ionization of H2O(liq) at 298 K.

ISSN:0008-4042    

DOI:10.1139/v76-477

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Crystals of CaK2As2O7and CdK2P2O7, both grown from the melt, are monoclinic withZ = 4. The lattice parameters area = 9.222(6),b = 5.835(3),c = 14.698(10) Å, β = 105.84(5)° with space groupP21/cfor the diarsenate anda = 9.737(2),b = 5.548(1),c = 12.766(2) Å, β = 106.50(2)° with space groupC2/cfor the diphosphate. The structures were refined by full-matrix least-squares methods utilizing 2070 reflections (R = 0.056) for the diarsenate and 1145 reflections (R = 0.067) for the diphosphate. Both structures contain pseudo-hexagonally packed anions, in staggered configurations, forming layers with the divalent cations in six coordinate sites between the layers. The average M—O bond lengths are 2.342 and 2.290 Å for M = Ca and Cd respectively. The K ion has nine oxygen atoms with mean K—O bond lengths of 2.943 and 3.020 Å in the diarsenate in the coordination sphere. The mean of the ten shortest K—O is 2.939 Å in the diphosphate.

ISSN:0008-4042    

DOI:10.1139/v76-478

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Oxetane has been polymerized using both triethyloxonium hexafluorophosphate and triphenylmethyl hexafluorophosphate as initiators at −30 °C. The former gives a slow polymerization with a slow initiation process. The latter gives a rapid initiation and rapid initial polymerization which may slow down to rates similar to those found for the former initiator. The results are interpreted in terms of the formation of two types of tertiary oxonium ions. One type incorporates the oxetane molecule and is suggested to have a very rapid reaction with more oxetane. The second type does not involve the oxetane molecule but an ether linkage, such as in the polymer chain, and reacts only slowly with oxetane.

ISSN:0008-4042    

DOI:10.1139/v76-479

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The possibilities of improving the computational processing of chemical rate measurements, in the frame of linear and non-linear least-square fit methods, are investigated. A simple scaling technique to avoid the distortion of the fitted parameters, inherent in the logarithmic transformation of the rate equation, is tested on several examples, and an iterative discarding method for the selection of accurate data points is recommended.

ISSN:0008-4042    

DOI:10.1139/v76-480

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The partial pressure of KAlF4over K3AlF6–KAlF4melts at temperatures as high as 815 °C was measured by thermogravimetry. Melt activities were calculated from the measurements. The results are discussed with reference to the use of this salt mixture as a flux for aluminum alloys.

ISSN:0008-4042    

DOI:10.1139/v76-481

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Cobaltocene anions have been prepared electrochemically in dimethylformamide. Their reaction with various electrophiles gives, in quantitative yields, substituted cyclopentadiene cobalt cyclopentadienyls, some of which cannot be prepared by usual methods.Substituted cyclopentadiene cobalt cyclopentadienyls are also obtained in excellent yield, by reaction of electrochemically generated cobaltocene with organic halides.

ISSN:0008-4042    

DOI:10.1139/v76-482

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The oxidation of several substituted cyclopentadiene cobalt cyclopentadienyls electrochemically, by air, by hydrogen ions, and by triphenylmethyl tetrafluoroborate has been studied. The derivatives with anexohydrogen yield the corresponding cobalticinium salts. When theexosubstituent is CH3or C6H5, a degradation occurs. If theexosubstituent is CO2CH3, oxidation by triphenylmethyl tetrafluoroborate takes place withendohydrogen elimination, leading to the substituted cobalticinium salt in quantitative yield.

ISSN:0008-4042    

DOI:10.1139/v76-483

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The kinetics of the gas phase thermolysis of 2-vinyloxirane (4) have been studied over the temperature range 270–310 °C. The racemization of chiral4occurs six times faster than the structural isomerization to 2,3-dihydrofuran, (E)- and (Z)-2-butenal, and 3-butenal. The butenals undergo a slow thermolysis to propene and carbon monoxide.cis-Deuterio- andtrans-3-deuterio-vinyloxirane have been synthesized and their interconversion is slow. Deuterium kinetic isotope effects onmono- anddideuterio-4suggest that for the formation of the butenals the rate determining step involves rupture of the oxirane C—O bond. The dihydrofuran is produced by thermolysis of the oxirane C—C bond. The preferred mechanistic interpretation is that a carbon–oxygen diradical serves as an intermediate for butenal formation, and that a carbonyl-ylide is involved in the formation of the dihydrofuran.The relative rates, at 307.4 °C, ofcis–trans-5-isomerization:dihydrofuran formation:racemization: butenal formation for 3-deuterio-2-vinyloxirane are 1.0:0.88:40.2:5.94, respectively.

ISSN:0008-4042    

DOI:10.1139/v76-484

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The syntheses of 2-isopropylamino-1-(5-hydroxy-4H-pyran-4-on-2-yl)ethanol and the corresponding 4-pyridone and 1-methyl-4-pyridone analogues are described. The selective reduction of an aliphatic nitro group in the presence of a benzyl ether linkage was a key step in the reaction sequence.

ISSN:0008-4042    

DOI:10.1139/v76-485

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The chromyl chloride oxidations of cyclohexene and 1-methylcyclohexene have been reexamined. The products from cyclohexene were found to be cyclohexanone,cis- andtrans-2-chlorocyclohexanols, 2-chlorocyclohexanone, cyclohex-2-enol, cyclohex-2-enone, and cyclohexene oxide. Treatment of cyclohexene oxide with chromyl chloride produced onlytrans-2-chlorocyclohexanol and 2-chlorocyclohexanone. The products from 1-methylcyclohexene were 2-methylcyclohexanone, 1-methylcyclopentyladehyde,cis- andtrans-2-methyl-2-chlorocyclohexanol, 2-methyl-2-chlorocyclohexanone, 2-methylcyclohex-2-enone, and 4-methylcyclohex-2-enone. Treatment of 2-methylcyclohexene oxide with chromyl chloride yielded only 2-methylcyclohexanone and 1-methylcyclopentylaldehyde. The origin of the various products and possible mechanisms for their formation is discussed. A 1,3-cyclic addition reaction is proposed for the formation of thecis-chlorohydrins.

ISSN:0008-4042    

DOI:10.1139/v76-486

出版商:NRC Research Press    

年代:1976

数据来源: NRC