| Summary: | This thesis describes some aspects of the formation of addition products in the chlorination of polycyclic aromatic compounds. The chlorinations of polycyclic hydrocarbons, represented by naphthalene and related compounds, have been investigated mainly from the point of view of adduct formation, and numbers of new addition products derived from those, as well as old ones of still unknown structure, have been clarified with regard to their structures and properties, using infrared, ultra-violet and proton magnetic resonance spectroscopy. As a chlorinating agent, either sulphuryl chloride or molecular chlorine has been used, and the electrophilic nature of the former reagent has also been qualitatively established. Naphthalene, alkylnaphthalenes and halonaphthalenes, when treated with sulphuryl chloride with or without a solvent, give products similar to those obtained with molecular chlorine. By heating naphthalenes with sulphuryl chloride in excess, more highly chlorinated adducts were obtained together with some poly-chlorotetralones. Under conditions in which napthalene reacts slowly with sulphuryl chloride, chloronapthalenes do not react significantly, whereas alkylnaphthalenes react more rapidly, than naphthalene itself does, and give adducts as well as products of substitution. Addition of chlorine always occur in the ring, to which the substitution takes place in accordance with the rules governing the electrophilic substitution. l-Alkylnaphthalenes with straight chain and acenaphthene give side-chain chlorinated tetrachlorides as the main addition products. The formation of these unexpected adducts has been explained on the basis of the hyperconjugative loss of proton during the chlorine addition process. Chlorination of naphthols in acetic acid gives various ketopolychlorides, the structures of which have been spectroscopically investigated. 2,4-Dichloro-napth-l-ol and related naphth-l-ols of similar structure have been found to involve the initial electrophilic attack on the 2- rather than on the 4- position, giving unstable 1-keto-l,2-dihydronaphthalenes which then undergo the anionotropic isomorisation to yield stable l-keto-l,4-dihydronaphthalenes. Esters of naphth-l-ols behave differently, depending on the solvents used; in acetic acid the products are similar to those obtained from naphth-l-ols, however, in chloroform, 2,3,4-triehloro-l tetralones are formed, which are not highly stable and gradually lose hydrogen chloride to give 2,4-dichloro-naphth-l-ols. By similar treatment with chlorine, naphthyl-amines readily afford polychlorotetralones, for which a sequence involving the hydrolysis of the intermediary ketimine hydrochlorides has been suggested. Infrared, ultraviolet and proton magnetic resonance spectra of more than forty addition products have been recorded.
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