Naphthalene, sodium-liquid ammonia reduction

Many expensive reductions such as the Birch reduction of naphthalene to isotetralin, benzene to cyclohexene, with metallic sodium and liquid ammonia, or reduction with LiAlHa, can generally be carried out electrochemically at much lower cost and under safe conditions. Electrochemical processes allow fluorinations to be carried out without using fluorine gas. Conducting polymers have been made by electrochemical processes which operate under ambient conditions, and the polymer can be synthesized, doped and shaped in film form in a single step. 

Naphthalene is reduced to 1,4-dihydronaphthalene by sodium and alcohol. Isomerization of this product to 3,4-dihydronaphthalene occurs with sodamide in liquid ammonia. Tetrahydronaphthalene (tetralin) is formed from naphthalene by sodium in amyl alcohol or by reduction with nickel-aluminum alloy and aqueous alkali. Catalytic hydrogenation of naphthalene can be stopped at the tetralin stage over copper chromite, Raney nickel, or alkali metal catalysts. cis-Decahydronaphthalene is produced by high-pressure hydrogenation of tetralin over Adams catalyst, whereas a mixture of cis- and trans-decalins is obtained from naphthalene under the same conditions. ... 

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.- ... 

Furanoid glycals are not stable to the acidic conditions used to prepare the pyranoid congeners. Scheme 4 illustrates a very mild method for preparing furanosyl chlorides, which undergo efficient reductive elimination on treatment with lithium in liquid ammonia. Alternatively, a Zn-Ag couple adsorbed on graphite will reduce furanosyl bromides and the corresponding chlorides react with the radical anion prepared from naphthalene and sodium. ... 

Dauben and Bertelli synthesized heptalene (9) starting with reduction of naphthalene-1,5-dicarboxylic acid (4) with sodium and ethanol in liquid ammonia to the... 

The removal of arylsulphonyl groups is often difficult [259]. They are very stable towards alkalis and to bring about acidic hydrolysis usually requires heating with aqueous hydrochloric acid under pressure, or refluxing with 48% hydrobromic acid in the presence of phenol [260, 261]. Arylsulphonamido derivatives are also unaffected by catalytic reduction, however they may be cleaved reductively with sodium in butanol [254] or liquid ammonia [178, 257, 258, 262], or with sodium naphthalene in 1,2-dimethoxyethane [263]. 

---