1.3- Dimethyladamantane

A mixture of 24 g of 1,3-dimethyladamantane and BO ml of bromine was refluxed for 6 hours. The reaction product mixture was cooled, taken up in about 200 ml of chloroform, and poured onto ice. The excess bromine was removed by adding sodium hydrosulfite. The chloroform layer was separated from the aqueous layer, dried, concentrated in vacuo, and distilled at reduced pressure to yield 30.5 g of product having a boiling point of about 11B°C at 5-6 mm np = 1.5169-1.51B2. The product was identified by nuclear magnetic resonance (NMR) and elemental analyses as 1-bromo-3,5-dimethyladamantane. 

A similar pattern is revealed with adamantanes. 1,3-Dimethyladamantane over cobalt(III) fluoride yields only 5-10% of products with the adamantane skeleton intact, but when 1,3-bis-(trifluoromethyl)adamantane is fluorinated a 60 % yield of perfluoro(l, 3-dimethyladamantane)... 

Fig. 10. Diffusion of 1,3 dimethyladamantane in polybutadiene as function of concentration, at four temperatures. Lines are single tit of Eq. (20) with Eq. (9) to data (Ref.M>, with permission).

The energy differences between the alkyl adamantanes and analogs of different ring structure is very large 1-methyladamantane is 11.86 (E) kcal mole more stable than homoadamantane and 1,3-dimethyladamantane is 25.01 (E) kcal mole" more stable than 1,1-bishomoadamantane (tricy-... 

Earlier kinetics studies of acid-catalysed isomerization of alkyladamantanes suggested occurrence of a -methyl shift and this has been demonstrated by the predominant formation of 1,4-dimethyladamantane from 1,2-dimethyladamantane without passing through the more thermodynamically stable 1,3-dimethyladamantane. ... 

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