11.3 Alpha Halogenation of Aldehydes and Ketones p.348 Aldehydes and ketones can be halogenated at their -positions by reaction with cl. Br, or h in acidic solution H H+x x +HX11.3 Alpha Halogenation of Aldehydes and Ketones • Aldehydes and ketones can be halogenated at their a -positions by reaction with Cl2 , Br2 , or I2 in acidic solution p.348 H O + X2 X HX O + H +