6400-97-1

Upstream product

• 96-22-0 pentan-3-one 

Downstream Products

• 144032-75-7 3-Pentanol-2,2,3,4,4-d(5) 

Relevant academic research and scientific papers

Potential Energy Profiles for Unimolecular Reactions of Isolated Organic Ions: CH3CH2CH=N(+)HCH3 and (CH3)2C=N(+)HCH3

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.

N-heterocyclic carbene-catalyzed conjugate additions of alcohols

An efficient intermolecular conjugate addition of alcohols to activated alkenes catalyzed by N-heterocyclic carbenes has been developed. With 5 mol % of the free carbene derived from IMes?HCl, unsaturated ketones and esters are competent substrates, and a variety of primary and secondary alcohols can be employed as the nucleophile. No oligomerization is observed under these mild conditions for effective hydroalkoxylation. In addition to reactions with activated alkenes, IMes catalyzes the formation of vinyl ethers through the 1,4-addition of alcohols to ynones and promotes tandem conjugate addition/Michael cascade reactions. Preliminary data support a Bronsted base mechanism with the free carbene.

Highly efficient C-C bond-forming reactions in aqueous media catalyzed by monomeric vanadate species in an apatite framework

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.

Insight into binding of alkanes to transition metals from NMR spectroscopy of isomeric pentane and isotopically labeled alkane complexes

Alkane complexes of the type Cp′Re(CO)2(alkane) (Cp′ = cyclopentadienyl or (isopropyl)cyclopentadienyl; alkane = isotopomers of n-pentane and cyclopentane) have been characterized using NMR spectroscopy following photolysis of Cp′Re(CO)3 in the appropriate alkane at 163-193 K. In the case of n-pentane, three different complexes are observed corresponding to binding of the three different types of carbon in this alkane. ROESY NMR experiments indicate that these isomeric complexes are slowly interconverting intramolecularly at 173 K. The order of the energetically preferred site of coordination is methylene (C2) ≈ central methylene (C3) > methyl (C1) but with a spread of -1. Isotopic perturbation of resonance (IPR) experiments, conducted on several isotopomers of (i-PrCp)Re(CO)2(1-pentane), showed a large shielding of the 1H NMR chemical shift of the proton in a bound CHD2 moiety (δ -3.62) and CH2D (δ -2.64) compared with that of a bound CH3 moiety (δ -1.99). Likewise, the value of 1JCH for the coordinated methyl group of isotopomers of (i-PrCp)Re(CO)2(1-pentane) reduces in the order CH3 > CH2D > CHD2. This suggests that the alkane coordinates in an η2-C,H fashion with a rapid exchange of bound hydrogen or deuterium within a methyl or methylene group, and that binding of a hydrogen atom is preferred over a deuterium by an amount of 0.23 ± 0.03 kcal mol-1. Copyright

Stereochemical analysis of deuterated alkyl chains by MS/MS

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.

The Mechanism of Ethylene Elimination from the Oxonium Ions CH3CH2CH=O+CH2CH3 and (CH3)2C=O+CH2CH3

The reactions of the metastable oxonium ions CH3CH2CH=O+CH2CH3 and (CH3)2C=O+CH2CH3 are reported and discussed.Various mechanisms for ethylene elimination, which is the principal dissociation route for these ions, are considered.It is shown by means of 2H-labelling experiments and analysis of collision-induced dissociation spectra that routes involving ion-neutral complexes pre-empt 'conventional' mechanisms for these processes.In contrast, the behaviour of the lower homologues CH3CH2CH=OR+ and (CH3)2C=OR+ (R = H, CH3) is consistent with the operation of 'conventional' mechanisms for ethylene expulsion.This contrast is interpreted in energetic terms.The significance of these results for the chemistry of homologous and analogous 'onium' ions containing a Z+-R function (Z = O, S, NH, NCH3; R= CnH2n+1, n 2) is explained.

Dioxetane Radical Cations in Solution. An ESR and Cyclic Voltammetry Study

The radical cation formed upon electrochemical oxidation either of adamantylideneadamantane 1 in an O2-saturated solution or of the corresponding dioxetane 2 is shown by ESR spectroscopy to be 2+.This radical cation is relatively long-lived in CH2Cl2:CF3CO2H:(CF3CO)2O solvent mixtures at low temperatures.The resolved hyperfine splittings are 0.325 mT (4H) and 0.075 mT (6H).Using deuterated derivatives, the larger splitting has been assigned to two pairs of γeq-protons and the smaller one to the two remaining pairs of γeq-protons and one pair of β-protons, with each β-proton situated in a different adamantylidine moiety of 2+ (the notation β and γeq refers to the stucture of 1).These data are consistent with a C2 conformation of 2+ which is twisted at the dioxetane ring and does not enantiomerize on the hyperfine time scale at -110 deg C.Dioxetane radical cations 11+ and 13+ generated from isopropylideneadamantane 10 and 3-pentylideneadamantane 12, respectively, have also been studied under similar conditions by ESR spectroscopy.Their hyperfine data give no evidence of twisting at the dioxetane rings and provide a further example for the sensitivity of the long-range splittings to orientation of bonds relative to the spin-bearing orbital.Cyclic voltammograms indicate that the Eo' value for 2 is 0.66 V anodic of 1 at -78 deg C, so that electron transfer from 1 to 2+ is exothermic by 15 kcal/mol.

Bifunctional Even-electron Ions. 1-Fragmentation Behaviour of ω-Methoxy-, ω-Hydroxy- and ω-Chloro-oxonium Ions

Bifunctional oxonium ions - generated from tertiary aliphatic alcohols containing an additional hydroxy, methoxy or chloro group at the end of an alkyl side-chain - do not markedly exhibit fragmentations typical of ordinary oxonium ions, but show as the main reactions those caused by functional group interaction, through-space interaction being the dominant factor.The main primary fragmentation is loss of the additional functional group X as HX, followed by loss of the side-chain originally separating the two functional groups, leading to carbonyl cations.This typical reaction sequence is initiated by proton migration from the oxonium moiety to the additional functional group.The reaction behaviour of the bifunctional ions is discussed.The lowest homologues show specific deviations from the general fragmentation behaviour.

Unimolecular Reactions of Ionized Alkanes

The unimolecular reactions of several CnH2n+2+. radical cations are discussed in terms of species involving an incipient carbonium ion coordinated to a radical.These species can be formed by stretching the appropriate bond in the ionized alkane.Subsequent isomerization of the incipient carbonium ion can give rise to rearranged structures in which a 1,2-alkyl shift has effectively occurred.By means of such mechanisms, much of the previously reported data concerning decomposition of ionized n-butane can be explained; in particular, the results of 2H-labeling studies can be interpreted.In addition, new labeling data are reported for ionized n-pentane and isopentane; the results indicate that both 1,2-methyl and 1,2-ethyl shifts precede or accompany dissociation of these C5H12+. species.Previously published 13C- and 2H-labeling data on ionized n-heptane are also considered; these results can be uderstood in terms of competing 1,2-methyl, -ethyl, and -propyl shifts.