摘要:

Hydrolysis of Co(II) has been studied up to 200 °C using a concentration cell with liquid junction of the type Pt(H2)|H+(a1)||H+(a2)|(H2)Pt. The effect of varying the initial solution pHand cobalt concentration has been studied at different ionic strengths. The hydrothermal hydrolysis for cobalt solutions between pH 3.9 and 9.6 is consistent with the equilibrium Co2+ + H2O → CoOH+ + H+. Higher hydrolytic species are not important. Hydrolysis increases with temperature and produces a buffering action at 200 °C. Thermodynamic quantifies for the hydrolysed species are reported.

ISSN:0008-4042    

DOI:10.1139/v78-069

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The reactions of K2PtCl4with pyridine derivatives L (L = py = pyridine, pic = picoline, and lut = lutidine) were studied in dimethylformamide (DMF).The complexes (1) were isolated and the yield decreased with the order, 2,4-lut = 2-pic > 2,6-lut > 4-pic = py, which can be correlated to the steric hindrance of theorthomethyl groups. The compounds (2) can be converted to the compounds (3), the free ligand acting as catalyst and (3) is the final product of the above reactions. The compounds (3) can also be obtained from a DMF solution of [Pt(L)4]Cl2(L = py) at room temperature. A comparison of the above reactions in water and in DMF was also made.

ISSN:0008-4042    

DOI:10.1139/v78-070

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Calorimetric measurements on potassium chromate(V), K3CrO4(c), and related substances have provided enthalpies that lead to ΔHf0 = −370 ± 2 kcal mol−1for K3CrO4(c) at 298 K.

ISSN:0008-4042    

DOI:10.1139/v78-071

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The crystal structure ofcis-chlorobis(triethylphosphine)-1,8-naphthyridineplatinum(II) tetrafluoroborate has been determined by single crystal X-ray diffraction and refined to anR-value of 0.063. The cell dimensions area = 1.4246,b = 1.2676,c = 1.6530 nm, β = 115.66°. The space group isP21/cwith 4 molecules per unit cell, and the measured density is 1.665 g cm−3. The structure is essentially a 4-coordinate square planar platinum(II) complex containing monodentate 1,8-naphthyridine. Interatomic distances to platinum are: Pt—Cl, 236.6(4); Pt—P(1), 225.4(4); Pt—P(2), 225.2(4); Pt—N(1), 208.3(11); and Pt—N(2), 304.5(14) pm. The structure is discussed in relation to variable temperature nmr studies of solutions, which indicate fluxional behaviour of the heterocyclic ligand.

ISSN:0008-4042    

DOI:10.1139/v78-072

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The unexpected inability of an α-phenyl group to accelerate the rate of vinyl ether hydrolysis more strongly than an α-methyl substituent,k(CH2=CPhOEt)/k(CH2=CMeOEt) = 0.2 for catalysis by H3O+at 25 °C, is examined and is found to be the result of two effects: (i) preferential initial state stabilization by phenyl and (ii) weak resonance interaction with the developing alkoxy carbonium ion in the transition state induced by the reactant-like character of the latter. A curved Brønsted relation for the hydrolysis of 3-methoxyindene catalyzed by carboxylic acids and monohydrogen phosphonate anions gives the Marcus theory parameters ΔG0≠ = 3 ± 1 kcal/mol andwr = 12 ± 1 kcal/mol.

ISSN:0008-4042    

DOI:10.1139/v78-073

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Rates of hydrolysis ofcis- andtrans-β-phenylvinyl methyl ethers,cis- andtrans-β-(p-nitrophenyl)vinyl methyl ethers, andcis- andtrans-β-cyanovinyl ethyl ethers were measured in concentrated (10–55 wt%) aqueous perchloric acids. The results show that thesecisandtransisomers do not interconvert under the hydrolysis reaction conditions, and that formation of the alkoxy carbonium ion intermediate in these reactions is therefore not reversible.

ISSN:0008-4042    

DOI:10.1139/v78-074

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Comparative reactions of some halogenogermanes with lithium(I), lead(II), and organosilicon Group VI species have been investigated, leading to the efficient syntheses of the chalcogermanes of the formula (MenH3−nGe)2E, where E = O, S, Se, Te;n = 0 → 3. The spectroscopic properties of the new bis(methylgermyl) and bis(dimethylgermyl) chalcogenides are discussed. Germanethiols and germaneselenols, viz. MenH3−nGeEH (E = S, Se;n = 0, 3) are isolated as intermediates in the reaction of digermoxanes with H2E and from equilibrium mixtures of (MenH3−nGe)2E with excess H2E. Evidence is presented for the condensation of the chalcogermanes to species of the type MenH3−nGe(EGeH3−nMen)2(n = 1, 2) and for the elimination of metallic selenium or tellurium giving digermanes of the type (MenH3−nGe)2(n = 1, 2).

ISSN:0008-4042    

DOI:10.1139/v78-075

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The proton nuclear magnetic resonance spectra of a reaction mixture of hydrazine and ethyl acetoacetate (EAA) in aqueous solution under flowing and stopped-flow conditions provides kinetic information concerning the rapid addition step to form the carbinolamine (CA) intermediate and the slower dehydration and cyclization steps to form theantihydrazone and 3-methylpyrazol-5-one, respectively. The addition step was studied while flowing at rates faster than the dehydration and cyclization rates so that no product signal was observed. Under these conditions, a broad signal resulting from the coalescence of the CH3proton resonances of EAA and CA is observed. Analysis of the line shape of this broad signal yields the addition rate constant, which has a value that appears to be pHdependent and is of the order of 103 M−1s−1. Stopped-flow spectra provide the time dependence for the reactant and product signals. Analysis of these time dependences provides information concerning the mechanism of product formation. In contrast with hydroxylamine, CA appears to undergo dehydration and cyclization at comparable rates in the pHrange, 8.8–9.2 when hydrazine is the nucleophile. In addition, theantihydrazone cyclizes at an appreciable rate. These intramolecular cyclization rates are compared with the intermolecular values.

ISSN:0008-4042    

DOI:10.1139/v78-076

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The chemical behaviour of 1,2-bis(trimethylsiloxy)cyclopropanes is described. Acid and base solvolyses as well as reactions with chlorine and bromine occur with opening of the ring leading to α-ketols, enones and β-diketones. Ketols and enones arise from a cyclopropanol type ring opening while the β-diketones resuit from the oxidation of the intermediate siloxycyclopropanols or cyclopropanediols. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v78-077

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Treatment ofN2-benzoyl-2′,3′,5′-O-triacetylguanosine and 2′,3′,5′-O-triacetyladenosine with buffered hydrazine gave equilibrium mixtures ofN2-benzoyl-2′(3′),5′-diacetylguanosine and 2′(3′),5′-diacetyladenosine, greatly enriched in the desired 3′-acetates. Fractional crystallization effected recovery of pure 3′,5′-diacetates in 60% yields. From these were prepared the 2′-O-tetrahydropyranyl derivatives required for guanosine and adenosine insertion in phosphotriester oligonucleotide synthesis.

ISSN:0008-4042    

DOI:10.1139/v78-078

出版商:NRC Research Press    

年代:1978

数据来源: NRC