Spectrométrie de Masse—IV: Fragmentation des Dicétones—ϵ

The mass spectra of ten symmetrical ?-diketones are reported and a number of fragmentation patterns are documented by deuterium labelling experiments. The McLafferty rearrangement involving one of the carbonyl groups is not an important fragmentation pathway although such a double rearrangement is observed for long-chained ?-diketones. Special attention has been given to the ions resulting from the loss of either a molecule of water or the neutral species C₂H₄ which may involve an electron-impact induced formation of cyclobutanol-type ions analogous to the photochemical Yang's reaction.     

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.     

Hétérocyclisations intramoléculaires par réaction d'oxymercuration. I — synthèse et configurations des hétérocycles

We have accomplished the intramolecular oxymercuration of γ-δ ethylenic alcohols, with different mercuric salts under different conditions. By “in situ” reduction, or by direct reduction of isolated mercuric compounds, we obtain, in some cases, diastereoisomers with different relative yields.     

Low-energy,low-temperature mass spectra. 9—The linear undecanols

The 70 and 12 eV mass spectra of the six linear undecanols are reported. Apart from undecan-1-ol, whose spectrum is akin to that of undec-1-ene, the spectra are dominated by peaks corresponding to loss of water and α-cleavage. The low voltage spectra are more readily interpreted.     

Toxic fluorine compounds containing the C—F Link—XII Some reactions of ω-fluoroacetophenone

The reaction between ω-fluoroacetophenone and sodium methoxide in methanolic solution has been investigated. The condensation at room temperature results in the formation of 2,3-epoxy-4-fluoro-1,3-diphenylbutan-1-one (I) and 2-fluoro-1,3-diphenyl-butan-1-one-4-al (II). From the latter 3-fluoro-2,4-diphenylfuran (V) has been prepared. A general method for preparing substitued fluorofurans thus becomes possible.     

Phosphoranes par fermeture trans-annulaire: III—Conformation—configuration—labilité

The analysis of the n.m.r. spectra of the two isomers of 1,6,6-trimethyl-3-phenyl-2,8-dioxa-5-aza-1-phospha ^vbicyclo[3.3.0]octane allows us to propose a conformation for each 5-membered ring and for the configuration of the phosphorus atom. The lability of the H? P proton, revealed by high temperature experiments and by P? H ? P? D exchange, is significantly different in the two isomers.     

Na9[FeO3][FeO4] ein gemischtvalentes Oxoferrat(II,III) mit isolierten [FeO3]4— — und [FeO4]5— ‐Anionen

Na₉[FeO₃][FeO₄]a Mixed Valent Oxoferrat(II, III) with Isolated [FeO₃]^4— — and [FeO₄]^5— Anions Na₉[FeO₃][FeO₄] has been formed and obtained from a redox reaction between CdO and iron metal (reaction container) and Na₂O in the presence of NaOH at 450 °C as orange‐red transparent single crystals. The crystal structure determination (IPDS data: Pca2₁, a = 956.2(2) pm, b = 999.1(2) pm, c = 1032.3(2) pm, Z = 4, R_all = 0.0455) reveals the presence of isolated complex anions, [FeO₃]^4— and [FeO₄]^5—.     

Analogues méso-hétérocycliques du dihydro-9,10 anthracène. XII — Sur quelques indoles dérivés de la dibenzo-p-dioxine

2-Aminodibenzo-p-dioxine undergoes facile condensation with different ω-bromoketones to give 2-aroylmethylaminodibenzo-p-dioxines, which undergo Möhlau-Bischler cyclisation under certain conditions. Some indolo[5,6-b] [1,4]benzodioxine were prepared by this method and their biochemical effect on the zoxazolamine hydroxylase in rats was studied.     

Analogie Photochimique. II—Cyclisation des Aldéhydes δ,ε Insaturés sous Impact Electronique

The mass spectra of 4, 4-dimethyl δε-unsaturated aldehydes show an ion at m/e 126 which results from the elimination of a neutral olefin directly from the molecular ion. This fragmentation is shown to occur through a cyclohexanone intermediate involving a process whcih has its equivalent in the photochemistry of these aldehydes. The abundance ratios of the unimolecular metastable decompositions of these m/e 126 ions are in excellent agreement with the proposed mechanism.