2 -1 -methyl-naphthalene dianion

Naphthalene (49) reacts with sodium in liquid ammonia to form a red complex which is quenched by methanol to form the 1,4-dihydro derivative (51), and may therefore be assumed to be the dianion (50).- If alcohol is present in the reaction mixture, then the 1,4,5,8-tetrahydro derivative (52) is formed (Scheme 6). 1-Naphthyl derivatives are reduced in the unsubstituted ring, whereas there is a maiked preference for reduction of the substituted ring in 2-methyl- and 2-methoxy-substituted isomers. This preference is not as well defined for bulkier substituents, however, and is reversed in the case of 2-f-butylnaphthalene further details are in a 1970 review. Because of the facile isomerization of the 1,4-dihydro isomers to conjugated derivatives, overreduction occurs readily and ether groups are fairly readily hydrogenolyzed. It is therefore important to select the reaction conditions with care.- ... 

Repetitive Alkylation Reaction. The tetrahydrofuran-insoluble materials, in certain instances, were subjected to a second alkylation reaction. In these cases there were three notable differences in the experimental results. First, the green color of the naphthalene radical anion and dianion persisted for a significantly longer time following the addition of the coal residue. Second, gas evolution, presumably butene-1, was detectable during the addition of butyl iodide or butyl mesylate but, significantly, not during the addition of methyl iodide. Third, the rate of formation of potassium iodide was much more rapid, such that the rate difference between butyl iodide and methyl iodide was not evident. 

Curiously, in reacting with methyl iodide so readily to make dimethyl dihydro products, the perylene dianion is distinct from the radical anion of naphthalene, which primarily reduces methyl iodide to the methyl radical and the iodide anion. 

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