摘要:

Sodium ion preferentially forms long lived complexes with dimethylsulfoxide orN,N-dimethylformamide, in mixtures of either of these solvents with either ethanenitrile or propanone. No long lived complexes are observed in solvent mixtures of water or methanol with ethanenitrile or propanone.

ISSN:0008-4042    

DOI:10.1139/v72-623

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

In the vacuum ultraviolet photolysis of cyclopentanone, the major modes of fragmentation of the electronically excited ketone are:The sum of the quantum yields for reactions A and B is 0.87 at 147.0 nm and these reactions become less important as the incident energy is increased. A pressure study at 147.0 nm of the partitioning of the tetramethylene diradical between paths A and B indicates that the ratiokA/kBis approximately 8. The quantum yield for reaction 8 is only 0.02. The remainder of the decomposition of cyclopentanone is accounted for by reactions 4 and 5, which appear to become more significant as the incident energy increases. The mechanisms for reactions 6 and 8 are best interpreted in terms of diradicals of structure (CH2)nwheren = 1, 3, and 4. The lack of non-acyl σ-cleavage at 147.0 nm is an indication that the absorption of energy occurs at the carbonyl group.

ISSN:0008-4042    

DOI:10.1139/v72-624

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A new form of Cu3V2O8was prepared at 30 kbar and 900 °C. The unit cell has dimensionsa = 6.2493(9),b = 7.9936(9),c = 6.3776(10) Å, β = 111.49(1)°, and the space group isP2/c. The crystal structure, refined by least-squares to a finalR = 0.054, using 848 reflections, is similar to that of Mg3V2O8. Chains of edge-shared M2 octahedra run along thecaxis at abouty = ± 1/4 with M1 octahedra sharing two edges with the M2 octahedra. These octahedral networks at abouty = ± 1/4 are linked by corner-shared V–O tetrahedra. The distortion from the Mg3V2O8structure can be explained on the basis of the Jahn–Teller effect in which four of the octahedral Cu—O distances shorten to 1.93–1.99 Å and two Cu—O distances lengthen to 2.3–2.6 Å.

ISSN:0008-4042    

DOI:10.1139/v72-625

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The ligand exchange reaction between InL3con plexes (L = CF3•CO•CH•CO•R−anion; R = methyl,i-butyl, phenyl, 2-naphthyl, and 2-thienyl) and excess free ligand (HL) has been studied in the solvents diisopropyl ketone, acetonitrile, benzene, and dimethylsulfoxide. Studies of the lifetimes of the reactants as obtained from their19F n.m.r. line-widths show that the exchange is first order in InL3concentration, but zero order in free ligand concentration. The coalescence temperature for the collapse of the n.m.r.19F chemical shift between free and complexed ligand (~50 Hz) yields ΔG≠for the exchange. The results are in agreement with the known stereochemical properties of indium(III) complexes. The rate-controlling process in the exchange is identified as the. rotation of one monodentate ligand about a partial double bond prior to intramolecular proton transfer to a second monodentate ligand.

ISSN:0008-4042    

DOI:10.1139/v72-626

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Tetracyclo[3.3.1.13.7.01..3]decane (i.e., 1,3-dehydroadamantane or DHA) and its 5,7-dimethyl derivative may be synthesized from the corresponding 1,3-dibromoadamantane compounds with sodium–potassium alloy in ether or heptane. These highly strained cyclopropyl compounds are very reactive towards free radical and electrophilic reagents. They homopolymerize 140–160° to thermally resistant, insoluble materials and spontaneously copolymerize with oxygen in solvents at room temperature. Reaction with bromine in ether at −70° yields an intermediate bromoadamantyloxonium tribromide which decomposes to 1-bromo-3-ethoxyadamantane on warming. Other rapid reactions of these strained 1,3-dehydroadamantanes are reported.

ISSN:0008-4042    

DOI:10.1139/v72-627

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Rates, activation parameters, and kinetic α-deuterium isotope effects are reported for solvolysis ofp-methyl-benzyl chloride in 80% trifluoroethanol–water, and in ethanol–water andt-butyl alcohol–water of varying solvent compositions. The α-deuterium isotope effect in trifluoroethanol–water (kH/kD = 1.14 per D) indicates approximately limiting behavior. Results in the other solvents (kH/kD = 1.04–1.08) indicate considerable nucleophilic participation by solvent in the transition state. 2,4,6-Trimethylbenzyl chloride gavekH/kD = 1.09 in 80% ethanol–water butkH/kD = 1.16 in 80% trifluoroethanol–water. 2,4,6-Tri-t-butylbenzyl chloride showedkH/kDeffects of 1.13–1.15 int-butyl alcohol–water and 1.15–1.16 in ethanol–water. The higher kinetic isotope effects for solvolysis of these trialkylbenzyl chlorides are discussed in terms of steric hindrance to nucleophilic participation by solvent. N.m.r. chemical shifts give evidence for steric compression of the benzylic protons in 2,4,6-tri-t-butylbenzyl chlorides.

ISSN:0008-4042    

DOI:10.1139/v72-628

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Using an energy-resolved electron beam, appearance potentials for,, andfragment ions from hydrocarbons of formula C3H4, C3H6, C4H6, C4H8, and C5H10have been measured. In each case the fragment appears to have a common structure, corresponding to,, and. Ionization potentials have been measured for propargyl radical (8.68 V), methallyl radical (7.54 V), and 2-methylallyl radical (7.89 V). Corresponding ionic heats of formation are propargyl 281 ± 3 kcal/mol, methallyl 204 ± 3 kcal/mol, and 2-methylallyl 211 ± 5 kcal/mol. Thefragment ion is 25 kcal/mol more stable than propargyl ion, and is almost certainly cyclopropenyl ion. Ionization potentials for propyne, allene, cyclopropene, 1- and 2-butyne, and fifteen isomers of formula CnH2nhave also been measured by monoenergetic electron impact.

ISSN:0008-4042    

DOI:10.1139/v72-629

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Data are presented for the results of γ-radiolysis on cyclopentane, methyl cyclopentane, cyclopentene, and cyclopentadiene, held as solutes in adamantane matrices. Data from this particular matrix isolation technique are in accord with liquid phase studies for cyclopentane and cyclopentene, and indicate that tertiary hydrogen loss occurs in methyl cyclopentane, and that cyclopentadiene yields at least three radicals. Two of the radicals derived from cyclopentadiene have been identified as the C5H5•entity with five equivalent protons, and theallylic-type radical formed by hydrogen atom addition to molecular C5H6.

ISSN:0008-4042    

DOI:10.1139/v72-630

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

cisandtransisomers of 1,4-dimethyl-4-nitro-1,4-dihydro-1-naphthyl acetate (1) have been isolated from a mixture of 1,4-dimethylnaphthalene and nitric acid in acetic anhydride by quenching at −40°. At room temperature only 1-methyl-4-nitromethylnaphthalene (4) is obtained. The conversion of 1,4-dimethylnaphthalene to4and of thecis(1a) andtrans(1b) adducts to4, by nitric acid in acetic anhydride, has been followed by n.m.r. 1,4-Dimethyl-4-nitro-1,4-dihydro-1-naphthyl nitrate (5) appears to be the immediate product from nitration of 1,4-dimethylnaphthalene in acetic anhydride, methylene chloride, or nitromethane. In acetic anhydride5is converted into1. Decomposition of1in acetic acid gives 1,4-dimethyl-2-naphthyl acetate and some4. The formation of4in this reaction is suppressed by urea.

ISSN:0008-4042    

DOI:10.1139/v72-631

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The title compound,9, has been synthesized in an eight-step process, starting with corticosterone (1). The Weidenhagen reaction on1converted the 17-COCH2OH to an imidazole. Reduction with lithium–ammonia–methanol gave 17β-(4(5)-imidazolyl)-5α-androstane-3β, 11β-diol (3) which could be selectively oxidized to the 3β-ol, 11-one, which was then converted to the oxime and hydrogenated to the 3β-ol, 11β-amine,6. Oxidation of the 3β-ol to the 3-one, oximation and sodium–propanol reduction gave9.

ISSN:0008-4042    

DOI:10.1139/v72-632

出版商:NRC Research Press    

年代:1972

数据来源: NRC