Page 98 - Pharm.Org.Chem-I 02-06-05-101

Stereospecificity of hydrogenation reaction

Case A: Stereospecificity is irrelevant (no chiral center is formed)

Case B: hydrogenation results in formation of 1 chiral center, so a pair
of enantiomers results.

3) Hydrohalogenation of alkenes (addition of HX)

a) Addition of HX to symmetric alkenes
The decreasing order of the reaction rate:

HI > HBr > HCl > HF

H2C CH2 HBr H3C CH2Br
ethylene

Sym. alkene

Symm.
alkene

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