摘要:

Magnetic susceptibilities between 80 and 300 K and57Fe Mössbauer parameters between 4.2 and 295 K are reported for Fe(SO3F)2. These data have been analysed via a crystal field model including spin–orbit and spin–spin coupling. The compound is trigonally distorted by an elongation along the [111] axis of the FeO6octahedron, and the ground state is the orbital doublet. The quadrupole coupling constant e2qQ is positive, and no rhombic distortion could be detected. The electronic spectrum shows a splitting of the5Egexcited level, presumably by a dynamic Jahn–Teller effect, andAttempts to fit a low-temperature magnetic perturbation Mössbauer spectrum using a pseudo-spin Hamiltonian were only partially successful, but suggest that the g tensor is highly anisotropic withand that the internal hyperfine field is small. Spin relaxation in Fe(SO3F)2is fast at all temperatures down to 4.2 K and in applied magnetic fields of up to 5.0 T.

ISSN:0008-4042    

DOI:10.1139/v77-021

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Iodonium nitrate (generated by reaction of iodine chloride with silver nitrate in chloroform–pyridine) reacts with a variety of unsaturated substrates to form the following: 1,4-conjugate addition products of the type alkenyl pyridinium nitrates; alkyliodopyridinium nitrates; products of aromatic iodination of both phenols and anilines; substituted benzodihydrofurans; tetrahydrofurans and tetrahydropyrans; polycyclic bridged ethers; lactones; thiazolines.

ISSN:0008-4042    

DOI:10.1139/v77-022

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The stereochemistry of the products of addition of iodonium nitrate to a series of cycloalk-2-en-1-ols indicates that the intermediate iodonium ion is formedcisto the neighbouring hydroxyl in the case of five-, six-, and seven-membered cyclic alkenols andtransto the hydroxyl in the case of cycloct-2-en-1-ol. The rates and Arrhenius parameters for the second-order additions of iodonium nitrate to these and other unsaturated substrates have been determined. An α-hydroxy group enhances the rate of addition over the corresponding alkene when the iodonium ion is formedcisto the hydroxyl and has the opposite effect when it is formedtransto the hydroxyl. This evidence for neighbouring hydroxyl group participation in additions of iodonium nitrate is in contrast to the known chemistry of iodine isocyanate and iodine azide. The effects of structural changes of the substrate on the kinetic and energetic parameters in iodonium nitrate additions are discussed and compared with those of other pseudo-halogens.

ISSN:0008-4042    

DOI:10.1139/v77-023

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Proton magnetic resonance spectra of methyl 4,6-O-benzylidene-α- and β-D-glucopyranosides (1and10) and their mono-substituted derivatives are determined in dimethyl sulfoxide solution. Assignments of the hydroxyl group resonances of1and10are confirmed by means of INDOR techniques. It is shown that the position of the hydroxyl substituent of the mono-substituted derivatives of1and10can be determined by using the coupling constantsJH—C—O—H. It is proposed that the vicinal diols of1and10give 1:1 associations with dimethyl sulfoxide molecules, and the C—H and O—H bonds at position 2 of the mono-substituted derivatives of1are approximatelyanti.

ISSN:0008-4042    

DOI:10.1139/v77-024

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The reaction of α-diazoacetophenone (1) with methanolic sodium methoxide in dilute solution gives 3-benzoyl-5-hydroxy-4-phenylpyrazole (4), 3-benzoyl-4-hydroxy-5-phenyl-pyrazole (5), 3-benzoyl-5-methoxy-4-phenylpyrazole (9), 3-benzoyl-4-phenylpyrazole (6), 5-benzoyltetrazole (7), 3,6-dibenzoyldihydro-s-tetrazine (10),cis- andtrans- β-benzoyl- α-phenyl-acrylic acid, acetophenone, methyl benzoate, and benzoic acid. The pyrazoles4,5, and9are considered to arise via reaction of1to give α-methoxyacetophenone followed by further reaction of the anion of the latter with1. Evidence in accord with this view was obtained by a study of the products formed when1was treated with methanolic sodium methoxide in the presence of 2-methoxy-4′-methylacetophenone. Acetophenone is considered to arise by reduction of1via phenylglyoxal 2-monohydrazone (37); condensation of1with the enolate ion derived from acetophenone then can give the pyrazole6, while condensation of1with37could give the tetrazole7.

ISSN:0008-4042    

DOI:10.1139/v77-025

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The catalytic decomposition of 2-propanol on hafnium dioxide has been investigated over the temperature range 355–397 °C by a micropulse reactor technique. The major reaction is one of dehydration to propene but dehydrogenation also occurs to a small extent. Isotope effect measurements with deuterio-2-propanols indicate that the rate-limiting step in dehydration involves cleavage of the β-carbon-hydrogen while in the dehydrogenation reaction it is cleavage of the α-carbon-hydrogen bond.

ISSN:0008-4042    

DOI:10.1139/v77-026

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Analysis of heat capacities for weak electrolytes (or 'almost strong' electrolytes) in terms of the various solute species is shown to require allowance for the thermal effects associated with the shift of the association or dissociation equilibrium when the temperature changes during a calorimetric measurement. This shift of equilibrium state is related to changes in the equilibrium constant and activity coefficient with temperature, as expressed by thermodynamic equations we have derived. These equations have been applied to aqueous MgSO4and HIO3to obtain the contributions of the solute species to the apparent molal heat capacities, which are then analyzed to yield heat capacities of MgSO4(aq, undiss.) and HIO3(aq, undiss.) and ΔCP0values for the association reactions of the ions to form these species.

ISSN:0008-4042    

DOI:10.1139/v77-027

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The condensation reaction of modified Reissert compounds with aldehydes was investigated. In the reaction of theN-ethoxycarbonyl Reissert analog1b, ethoxycarbonyl group migration takes place and carbonates of 1-isoquinolylphenylcarbinols (2b,c) are formed. No alkoxycarbonyl group migration was observed in the case of the dihydro-Reissert derivative6, but the cyclic urethane7and the amide8were obtained.

ISSN:0008-4042    

DOI:10.1139/v77-028

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The gas phase reaction of deuteriomethoxide with methyl benzoate and with methyl tri-fluoroacetate yields the corresponding carboxylate anions and not protiomethoxide ion. These results are opposite to what would be expected based upon the known reactions in solution of anions with esters. The reasons for the different behavior between the gas phase and the solution phase are discussed.

ISSN:0008-4042    

DOI:10.1139/v77-029

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The acid-catalyzed hydrogen isotope exchange of norcamphor1in DOAc–DCl–D2O is shown to follow the general theory (4) for exchange of a diastereotopic proton pair α to a carbonyl group. That is, the less reactive proton undergoes exchange via two channels. Through an analysis of a combination of the rate data for acid-catalyzed bromination and the pKBH+values for a series of cyclic and bicyclic ketones, we establish that the reactivity order in the former is controlled by ketone basicity and not, as has been suggested previously, by angle strain developed in a very enol-like transition state.

ISSN:0008-4042    

DOI:10.1139/v77-030

出版商:NRC Research Press    

年代:1977

数据来源: NRC