Replacement of halogen bound to olefinic or aromatic systems

Replacement of halogen bound to olefinic or aromatic systems 

Substitution of hydrogen for halogen in compounds containing the halogen attached to doubly or trebly bonded carbon can often be effected by aluminum amalgam,444 lithium aluminum hydride,445 zinc dust in pyridine and glacial 

Kharasch and O. Reinmuth, Grignard Reactions of Nonmetallic Substances, Prentice-Hall, Inc., New York, N.Y., 1954. 

2-Chlorolepidine (20 g) and potassium hydroxide (6.3 g) are dissolved in alcohol (150 ml). Raney nickel (3 g) is added and hydrogenation (1 mole of hydrogen) is carried out at room temperature and atmospheric pressure. Reaction is complete in 16 h. The catalyst is filtered off and the alcohol is removed by distillation. The residue is extracted with ether, and the extracts are washed with water, dried, and evaporated. The crude lepidine is purified by distillation. Its boiling point is 126°/40mm. The yield amounts to 94%. 

However, using noble-metal catalysts for this hydrogenation of 2-chlorolepidine has the advantage that the reaction time is appreciably shorter, namely, 1.5-2 hours.451 

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