6400-97-1Relevant articles and documents
Mead,Williams
, p. 1654,1657 (1971)
Potential Energy Profiles for Unimolecular Reactions of Isolated Organic Ions: CH3CH2CH=N(+)HCH3 and (CH3)2C=N(+)HCH3
Bowen, Richard D.
, p. 403 - 408 (1982)
The slow unimolecular reactions of metastable CH3CH2CH=N(+)HCH3 and (CH3)2C=N(+)HCH3 ions are reported and discussed.Details of the mechanisms of these reactions are elucidated by 2H-labelling studies.Loss of C3H6 from these C4H10N(+) ions shown to occur after irreversible isomerisation to CH3CH2CH2N(+)H=CH2 and related structures.The behaviour of CH3CH2CH=N(+)HCH3 and (CH3)2C=N(+)HCH3 is compared with that of the lower homologues and contrasted with that of the oxonium ion analogues CH3CH2CH=O(+)CH3 and (CH3)2C=O(+)CH3.
Highly efficient C-C bond-forming reactions in aqueous media catalyzed by monomeric vanadate species in an apatite framework
Hara, Takayoshi,Kanai, Satoko,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Jitsukawa, Koichiro,Kaneda, Kiyotomi
, p. 7455 - 7462 (2007/10/03)
A calcium vanadate apatite (VAp), in which PO43- of hydroxyapatite (HAP), Ca10(PO4)6(OH) 2, is completely substituted by VO43- in the apatite framework, was synthesized. Physicochemical analysis of the VAp reveals the presence of isolated VO4 tetrahedron units with a pentavalent oxidation state. The VAp acts as a high-performance heterogeneous base catalyst for various carbon-carbon bond-forming reactions such as Michael and aldol reactions in aqueous media and the H-D exchange reactions using deuterium oxide. For example, a 200-mmol-scale Michael reaction under triphasic conditions proceeded rapidly, with an extremely high turnover number of up to 260 400 and an excellent turnover frequency of 48 s-1. No vanadium leaching was detected during the above reactions, and the catalyst was readily recycled with no loss of activity.
Stereochemical analysis of deuterated alkyl chains by MS/MS
Morizur,Taphanel,Mayer, Philip S.,Morton, Thomas Hellman
, p. 381 - 387 (2007/10/03)
Vicinally deuterated sec-alkyl phenyl ethers, CH3(CH2)(m)CH(OPh)CHD(CH2)(n)CH3, display significant differences in mass spectra between threo and erythro stereoisomers. MS/MS experiments, in which parent ions of a single mass are selected and their fragmentation patterns subsequently measured, show that alkene expulsion represents virtually the only decomposition pathway. Two types of MS/MS experiment are reported: mass- analyzed ion kinetic energy (MIKE) spectroscopy of metastable ions and collisionally activated decomposition (CAD) of stable ions. The expulsion of a deuterated alkene from a monodeuterated precursor yields ionized phenol, PhOH·+ (m/z 94). The expulsion of an undeuterated alkene yields PhOD·+ (m/z 95). Without exception, the ratios (PhOD·+/PhOH·+) from precursors in the threo series have values greater than their diastereomers in the erythro series. The ratio of ratios, r = PhOD·+/PhOH·+ for the threo divided by PhOD·+/PhOH·+ for the erythro, has a value of 1.2 for the 2- phenoxy-3-deuteriobutanes and larger values for all of the higher homologues up through the monodeuterated phenoxyoctanes (m + n = 4). The highest degree of stereoselectivity, r = 5.8, is measured for 3-phenoxy-4-deuteriohexane. Experiments with multiply deuterated analogues show that alkene elimination is highly regioselective, unlike the corresponding decompositions of ionized sec-alcohols or their acetates. The fact that a large fraction of ionized sec-alkyl phenyl ethers undergo stereospecific syn-elimination means that mass spectrometry has a useful capacity to distinguish one isotopically labeled diastereomer from another.
