(a) Using the reactants below, list in order (by letter, no period) those necessary to accomplish the given transformation. Note: not all steps may be needed. For any steps which are not used, type 'na'.
a. Na/NH3
b. Br2
c. PCl5
d. CH3Cl
e. HA
f. A
Step 1
Step 2
Step 3
Step 4