The mass spectra of some chlorinated pesticidal compounds

The mass spectra of nine bridged polycyclic chlorinated pesticidal compounds have been investigated, and fragmentation modes to account for the more abundant ions are postulated. The principal features of the spectra are ions corresponding to a set of retro-Diels-Alder decompositions, ions resulting from successive losses of Cl, HCl, or both, ions produced by combinations of a retro-Diels-Alder process with a preliminary or subsequent loss of Cl or HCl, and ions whose processes of formation more specifically involve the epoxide group.     

The mass spectra of some aromatic polyketones

The behaviour of some aromatic tri- and tetraoxo compounds and of their p-substituted derivatives under electron-impact has been investigated by means of high and low resolution mass spectrometry, metastable refocusing and deuterium labelling. Some characteristic fragmentation processes observed with these compounds indicate that their molecular ions exist in the enol form. The formation of principal fragment ions is discussed.     

Energetic consideration applied to the mass spectra of some aromatic compounds

It is shown that the ‘metastable’ mass spectra of a series of monosubstituted benzenes are consistent with reaction over the lowest available energy surfaces. The non-occurrence of some qualitatively possible decomposition pathways may therefore be used to place lower limits on the heats of formation of gaseous cations. Conversely, where characterized reactions are preempted by new reactions upon introduction of additional substituents, upper limits may be placed upon the heats of formation of the ionic products of the new reactions. The concepts are employed to deduce that C₃H₆ elimination from n-butylbenzence subsequent to ionization leads to ionized toluene rather than ionized methyleneclohexadience.     

The Raman spectra of some aromatic nitro compounds

The paper provides a re-appraisal of the analytical value of Raman spectroscopy in the investigation of aromatic nitro compounds. Correlations are found between the frequencies of the NO vibrations and the electron-donating and -withdrawing effects of substituents on the phenyl rings. Further, relations are discussed between the highest-frequency CH stretching mode and the electron density and number of nitro groups. The paper contains a large number of spectra of typical aromatic nitro compounds.     

The mass spectra of some pyrazole compounds

The mass spectra of ten pyrazole compounds have been determined. Fragmentation schemes have been derived by means of the metastable defocusing method. The predominant process is cleavage of the nitrogen-nitrogen bond resulting in expulsion of HCN. The process second in prominence is the loss of a nitrogen molecule after initial removal of a hydrogen radical or a substituent, giving the species [C₃H₂R]⁺, probably a cyclopropenyl ion. In general, the fragmentation pattern is strongly influenced by the substituent.     

‘Doubly charged ion’ mass spectra of some simple aromatic compounds

Benzene, toluene, phenol, diphenyl ether and the three isomeric dihydroxy-benzenes have been examined using an MS-9 mass spectrometer under conditions that allowed only ions having twice the normal amount of kinetic energy to be detected. These ions are, in fact, singly charged ions arising from charge exchange reactions of doubly charged ions of the same mass, occuring in the first field free region of the Spectrometer. It is argued that the spectra obtained yield essentially the distribution of doubly charged ions in the source region. These ‘doubly charged ion’ mass spectra are compared with the normal singly charged ion spectra of the compounds and the implications of the significant differences that are found, are discussed.     

Electron impact mass spectra of some substituted aromatic boronate derivatives of bifunctional compounds

The electron impact mass spectra of the 3,5-bis(trifluoromethyl)benzeneboronate, 2,4-dichlorobenzene-boronate and 4-bromobenzeneboronate derivatives of some bifunctional diols and aminoalcohols are characterized by prominent molecular ions with diagnostically useful modes of fragmentation. Many of the principal ions in the mass spectra retain boron in their structure.     

Electronic spectra and molecular symmetry for some aromatic compounds

Interpretations are given for the electronic absorption spectra of crystals of alkylbenzenes and benzene itself; these are based on molecular models that include somewhat out-of-plane positions for the carbon atoms in the benzene ring. The relation of stability and specific properties to structure for aromatic hydrocarbons is discussed.     

The mass spectra of some pyridazines,pyrido-pyridazines and related compounds

The mass spectral fragmentation behaviour of substituted sulphur containing pyridazines, pyrido (2,3-d) pyridazines and pyrido-thiazolo-pyridazines has been investigated and fragmentation patterns proposed.     

On the mass spectra of some alkyl digermanium compounds

This paper reports the monoisotopic mass spectra of the compounds (CH₃)Ge? Ge(CH₃)₃,(C₂H₅)₃Ge? Ge(C₂H₅)₃ and (CH₃)₃Ge? Ge(C₂H₅)₃. With the aid of metastable ion transitons and appearance potentials the fragmentation patterns can be given. The dominant reactions are explained in terms of the valence of the metal atom. According to the valence rule the possibility of forming an ion in which two germanium atoms are bonded to five other groups (alkyl or hydrogen) determines greatly the spectra, while successive elimination of the methyl groups appears to be difficult and elimination of the ethyl groups is a predominant process.     

The ion kinetic energy spectra of some chlorinated insecticides

The ion kinetic energy (IKE) spectra of the p,p′ and o,p′ DDT, DDD and DDE isomers have been examined. The results indicated that the decomposing [M-CCl₃] ions (b) (m/e 235) for the p,p′ and o,p′ DDT isomers were not energetically similar, suggesting retention of the positional identity of the aromatic chlorine substituents. Similar results were obtained for the [M – CHCl₂] ions (b) for the p,p′ and o,p′ DDD isomers. The IKE spectra of p,p′ and o,p′ DDE were indistinguishable, indicating loss of substituent identity of the aromatic chlorine group. The mechanistic and analytical consequences of these data are discussed. The IKE spectra of the four hexachlorocyclohexane isomers (V to VIII) are different and these spectra are obviously useful in the analysis and characterization of these structurally similar compounds. The differences in their reactivity must in some part be due to their different stereochemical orientations of the chlorine substituents.     

The mass spectra of reissert compounds

A series of Reissert compounds containing the quinoline, isoquinoline and phthalazine nuclei show the common feature in their mass spectra of the initial loss of the N-substituent and either of the substituents attached to the adjacent carbon atom.     

The mass spectra of some guanidines

The mass spectra of guanidine and ten of its derivatives have been studied under both high and low resolution conditions. Evidence was detected for the migration of methyl groups, the formation of intermediate three-membered ring structures and decompositions involving expulsion of N^. with release of kinetic energy.     

The mass spectra of some chromans

The mass spectra of 4-p-hydroxyphenyl-2,2,4-trimethylchroman and of its thia, selena and sulphonyl analogues are reported and discussed. Formal charge localization on the oxygen atom of the oxo compound is reflected in the production of an abundant [M - 15]⁺ ion. Lack of charge location on the heteroatom of the seleno compound leads to a retro-Diels-Alder reaction. The thio compound exhibits intermediate behaviour, but charge localization on the oxygen atoms is preferred in the sulphone.