Synthesis qns, one of the 2 ultimate tests in organic chemistry.
Combining most of the things you have learnt, just like how an espresso is brewed, the process is grueling but the end product just taste heavenly!
To approach a synthesis qn,
take note that you will definitely have a START molecule, and an END molecule.
Your job as a chem sleuth is to find out the mysterious guy who is in the MIDDLE.
Start by checking out the NEW functional groups between the END guy and the START guy!
Now the trick starts RIGHT NOW!
because YES, rather unbelievably but true, once you nail down the FUNCTIONAL group that is new, ALL you NEED to do is to find out what FUNCTIONAL group has to come beforehand!
OK! now to the examples.
If you have a COOH,
1) acid hydrolysis of a CN
2) Oxidation of 1st, 2nd degree alcohol and aldehydes
If you have Acyl Chloride
Only 1 way
1) that comes from RCOOH, through PX5
If you have Alcohol
1) From alkaline hydrolysis of RX
2) 2 carbons, each with 1 OH side by side is a DIOL, comes from cold alkaline KMNO4
3) From Adding HX to alkenes (electrophilic addition)
4) From REDUCTION of Ketones, Aldehydes and RCOOHs
5) Last but not least, if you have an extra carbon appearing in your END product along with an OH group, it gotta come from HCN!
If you have HX
1) and 2), both from ROH.
1) Nucleophilic substitution by HX
2) Nucleophilic substitution by PX5
3) From ALKANES by free radical Substitutions
4) From ALKENES by electrophilic addition of HX
If you have AMINE,
1) Reduction of CN by either LIALH4 or Nickel Catalyst
2) from RX using excess conc NH3, heat in sealed tube