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No description available.

The reactions of chromyl chloride with aromatic hydrocarbons have been reviewed. The adducts formed from toulene and benzyl chloride have been shown by chemical and physical methods to consist of benzaldehyde co-ordinated to the reduced chromium. A range of other adducts have been similarly investigated, and the results are discussed. The kinetics of oxidation of a series of substituted toulenes and benzyl chlorides has been investigated. The results obtained have been correlated with the Hammett relationship. It has been possible to show that the oxidations proceed through a cyclic transition stage. The kinectic results have been investigated using Exner's criterion. A series of new compounds, involving substituted benzaldechydes co-ordinated to chromic chloride have been prepared.

This thesis describes the results of ab initio molecular orbital calculations employing a minimal basis of Gaussian orbitals on mono and disubstituted benzenes containing all possible combinations of the following substituents : H, F, CN, OH, CHO, CH 3) NH2 and NO2. The work is presented in three parts. The first outlines molecular orbital theory and the mathematical formulation of the one-electron properties which are discussed at a later point in the thesis. Part II describes the computational procedures employed. The computer programs which were used during the course of the work are discussed in some detail as are the Gaussian basis sets which were employed in the calculations. In particular, the scaling procedure and its effect on the calculated molecular properties is examined and a new method of upgrading the minimal basis to a double zeta one is also discussed. These double zeta basis sets were used in some of the calculations on the monosubstituted compounds. The third part of the thesis contains the discussion of the calculations. The close relationship between the wave functions of the benzene orbitals and those of the monosubstituted compounds is examined using contour diagrams of the molecular electron densities generated by a program specially written for the purpose. The text of this program and detailed operating instructions are included in an appendix. Wherever possible the calculated molecular properties are compared with empirical values. In particular, the calculations are used to assign the photoelectron spectra of many of the substituted benzenes.

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A study has been made of the properties of the electron deficient [pi] -systems in the compounds 3,5,6,8-tetranitro- acenaphthene (T.N.A.), 2,5-dinitro-l,8-naphthalic anhydride (2,5-D.N.N.A.), 3,6-dinitro-I,8-naphthalic anhydride (3,6-D.N.N.A.), 4,5-dinitro-I,8-naphthalic anhydride (4,5-D.N.N.A.), 2,4,5-trinitro-I,8-naphthalic anhydride (Tri.N-I,8-N.A.), 1,6,8-trinitro-2,3-naphthalic anhydride (Tri.N-2,3-N.A.) and 2,4,5,7-tetranitro-I,8-naphthalic anhydride (T.N.N.A.). Measurements on the visible absorption spectra of the donor-acceptor (charge-transfer) complexes formed between aromatic hydrocarbons and the above compounds have shown that the electron acceptor ability increases in the order T.N.A. [less than] 2,5-D.N.N.A. [tilde] 3,6-D.N.N.A. [tilde] 4,5-D.N.N.A. [less than] Tri.N-2,3-N.A. [tilde] Tri.N-l,8-N.A. The electron acceptor ability of T.N.N.A. could not be determined by this method. The extent of electron transfer in the complexes formed with N,N,N',N'-tetramethyl-p-phenylene diamine has been investigated by electron spin resonance spectroscopy and the results have confirmed that T.N.A. is the weakest acceptor. The association constants for the formation of complexes between T.N.A. and various methyl benzenes have been determined by nuclear magnetic resonance spectroscopy and the association constant and the heat of formation of the 3,6-D.N.N.A.-pyrene complex has been determined by visible spectroscopy. The values are comparable with those for other electron donor-acceptor systems. The electron spin resonance spectra of the radical anions of all the compounds, except 3,6-D.N.N.A. and Tri.N-2,3,-N.A., have been analysed and the experimentally determined spin densities have been found to be in good agreement with the values calculated by the Huckel and McLachlan molecular orbital methods. The relative spin densities at the proton sites in 3,6-D.N.N.A. have been estimated by a nuclear magnetic resonance method and found to agree qualitatively with the calculated values. The reactions of the compounds with the bases – methoxide ion, sulphite ion, amines - have been investigated, and the products have been characterised and correlated with the strength of the base used in the reaction. A possible mechanism for the reaction of 3,6-D.N.N.A. with the methoxide ion has been proposed. The preparation of the compounds under study have been described and the nuclear magnetic resonance, infrared and mass spectra have been recorded. The infrared and mass spectra have been discussed in terms of the structure of the compounds. The infrared spectra of the complexes formed with aromatic hydrocarbons have also been recorded and shown to be basically composites of the spectra of the individual components. A number of computer programs relevant to the present work and of general chemical application have been written and are presented as an appendix to the thesis.

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No description available.

A study has been made of the nitration of the three isomeric mononitroacenaphthenes and of the nitration of 4-ni tro-1,8-dimethyl¬naphthalene. The routes to the formation of 3,5,6,8-tetranitro¬acenaphthene, 3,4,5,6,S-pentanitroacenaphthene arid 2,4,5,7-tetranitro- 1,8-dimethylnaphthalene have been elucidated. A total of fourteen, hitherto unreported nitro-derivatives of the two parent hydrocarbons have been identified and procedures for the synthesis and isolation of twelve of these compounds have been developed. The oxidation of the higher polynitro derivatives of acenaphthene and 1,8 dimethynaphthalene has been investigated and this resulted in the production of two previously unreported polynitronaphthalic anhydrides, viz 2,4,5 trinitro-1,8-naphthalic anhydride and 2,4,5,7-tetranitro, 1,8-naphthalic anhydride. The reactions of 3,5,6,8-tetranitroacenaphthene and of 2,4,5,7-tetranitro-1,8-domethylnaphthalene with base has been studied and evidence obtained for the formation of a stable benzylic type anion. Base catylised coupling of 4-nitro-1.8-dimethylnaphalene has been shown to yield the previously unreported 4,4-dinitro-1,1'-naphthostilbene and 4,4'-dinitro-1,2-bis (1-naphthyl)ethane. The rates of nitration in glacial acetic acid of the three nitroacenaphthenes and 4-nitro-1,8-dimethylnaphthelene have been determined relative naphthalene. The substitution pattern in nitration products has been shown to be in good agreement woth the reactivity indices calculated using Huckel and MacLachlan molecular orbital methods. The infrared, eletronic, mass and [sup]1 H-nuclear magnetic resonance spctra of the parent hydrocarbons and their nitro-derivatives have been recorded where possible and discussed in terms of steric and electronic effects. The kinetics of the thermal decomposition of the nitro-derivatives of ancenaphthene and 1,8-dimethylnaphthalene have been investigated by differential scanning calorimetry and it has been found that the simple kinetic model could not be applied successfully to these compounds.

The rearrangement reactions of 1-methoxybenzobicyclo-[2,2,2]-octatriene derivatives in strong acid have been studied. In particular 1-methoxytetrafluoro-, 1-methoxytetrachloro-, and 1-methoxybenzobarrelene have been prepared labelled with 14C at C-4. Rearrangement of these compounds, in strong acid, leads in each case, to three isomeric ketones. The major product in each rearrangement was the corresponding benzobarrelenone, formed, in each case, by two distinct pathways. The 14C label in each benzobarrelenone was scrambled between C-4 and C-5 as a result of the two different mechanisms. A suitable degradation procedure has been devised which allows the 14C activity in C-4 and C-5 of each ketone to be determined, and hence an evaluation of the percentage rearrangement which proceeds by the two mechanistic pathways previously suggested.