Mass spectrometric studies on a β-ketosulfone

The fragmentation of the β-ketosulfone-γ-methylsulfonyl-γ-benzoylbutyronitrile under electron bombardment follows a number of different pathways: formation of the benzoyl ion (Major path); remova of acrylonitrile; liberation of the methylsulfonyl radical or of methylsulfonic acid; and finally elimination of a methylenecyano radical. The fragments observed can be explained by these five degradation paths. The reactions are compared with the photochemical cleavage of this β-ketosulfone in benzene solution.     

Mass spectrometric studies of cycloalkane-α-glycols

The mass spectral fragmentations of stereoisomeric cyclohexane-1,2-diols, p-menthane-2,3-diols, 1-hydroxycarvomenthols and 4-hydroxymenthols are discussed.     

Mass spectrometric comparison of ordinary and fully deuterated α- and β-carotene

The individual, deuterated, isomeric α- and β-carotenes were isolated from the green alga, Scenedesmus obliquus, cultivated in D₂O containing 99·7 to 99·8 atom percent deuterium. Mass spectroscopy showed that both the α- and β-deuterio-carotene preparations contained principally the fully deuterated pigment molecules (C₄₀D₅₆), small quantities of deuterated molecules with one proton (C₄₀D₅₅H) and yet smaller quantities of deuterated molecules with two protons (C₄₀D₅₄H₂). From statistical calculations the deuterio-carotene preparations also contained one to several isotopically-substituted deuterio-carotenes of each mass in the mass range 585 to 599 because of variation of the number of ¹³C and H atoms per molecule. The mass fragmentation of the deuterated pigments was analogous to that of the respective ordinary α- and β-carotene. It indicated that the protons in the C₄₀D₅₅H and C₄₀D₅₄H₂ molecules were distributed approximately randomly in various parts of the structure as in the terminal rings and in the ends and central portions of the polyene chain.     

Mass spectra of esters of α-hydroxy and α-methoxy acids

The most abundant fragment produced by electron bombardment of esters of the type R¹R²C(OR³)CO₂R⁴ is the R¹R²C = \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm O}\limits^{{\rm + } \cdot } $\end{document}R³ ion. Methyl glycollate (R¹ = R² = R³ = H, R⁴ = Me) eliminates the HCO˙ radical by a complex rearrangement involving the methylenic hydrogen atoms. The methyl and ethyl esters of methoxyacetic acid (R¹ = R² = H, R³ = Me, R⁴ = Me or Et) eliminate formaldehyde by the McLafferty rearrangement.     

Mass spectra of some acyclic α,β-unsaturated aldehydes,ketones and esters

The mass spectra of a series of aliphatic acyclic α,β-unsturated aldehydes, ketones and ester have been examined. The spectra do not show evidence for McLafferty rearrangements, alkoxyl migration or for fragmentations which are dependent upon the s-trans or s-cis conformations of the compounds. There is some evidence for cis-trans isomerism about the double bond.     

5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇的合成

以5-雄烯二醇为原料,用微生物转化的方法合成了两个重要的神经甾体5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇。所用菌种总枝毛霉为我们自己筛选,并首次应用于5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇的合成中。     

Studies in organic mass spectrometry-XIII: Investigation of electron-induced isomerisation of αβ- and βγ-unsaturated esters

The mass spectral fragmentation of methyl esters of α,β- and β,γ-unsaturated carboxylic acids has been studied. Deuterium labelling, metastable ion analysis and high resolution mass spectrometry have been utilised to elucidate the mechanism of a number of fragmentations and to check possible double bond migration prior to fragmentation. Some breakdown modes were found to occur through double bond migration. Additional support was provided by application of the ‘Metastable Ion Characteristics’ method. Partial isomerisation of molecular ions must therefore be accepted.