Question 1

Is there only one correct way to synthesise a molecule?

Accepted Answer

No, there are often multiple valid synthetic routes. The 'best' route is usually the one with the fewest steps, highest overall yield, and uses the cheapest/safest reagents. For exams, any chemically correct route using reactions from the syllabus will be credited.

Question 2

What is the difference between a synthon and a synthetic equivalent?

Accepted Answer

A synthon is an idealised, often unstable, charged fragment resulting from a disconnection (e.g., a carbocation R⁺ or carbanion R⁻). A synthetic equivalent is the actual, stable reagent used in the laboratory that corresponds to that synthon (e.g., a haloalkane R-X is the synthetic equivalent for the R⁺ synthon).

Question 3

Why can't I just perform a C-C bond forming reaction on any molecule?

Accepted Answer

Carbon-carbon bond forming reactions, like those using Grignard reagents, are very specific. Grignard reagents are strong nucleophiles and strong bases. They will react with any acidic protons in the molecule (e.g., from -OH, -COOH, or -NH₂ groups) before they react with a carbonyl group. Therefore, the molecule must be prepared correctly using FGI or protecting groups first.

Organic synthesis

What you need to know

Organic Synthesis: Your Chemical Roadmap