Question

                    Cl                                                                                                             =O
CH3-CH2-CH-Cl --(2KOH, H20)--> X1 --(K2Cr2O7, H2SO4)-->CH3-CH2-C-OH --(Cl2, P красный)--> X2 --(NaHCO3)--> X3 --(CH3-CH2-Br)--> X4

Answer 1

CH3-CH2-CH-(Cl)2 --(2KOH, H20)=CH3-CH2-CH-oh +koh