ChemistryChapter 21: Organic Synthesis
Exam Response (synthesis)
Typical tasks: two-step conversion; choose aq vs alc KOH; distil vs reflux; name a test for the product; one-carbon step with CN- (with haza
Learning objectives
- Explain exam response (synthesis) in simple chemical language.
- Connect 1. plan with 2. check using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Definition
Typical tasks: two-step conversion; choose aq vs alc KOH; distil vs reflux; name a test for the product; one-carbon step with CN- (with hazard word). Stay on the syllabus map. No extra reagents from the internet. Forward route: numbered steps with reagents and structures. Count carbons after each synthetic step; silent carbon loss is the most common multi-step mistake.
Important terms
- EXAM RESPONSE (SYNTHESIS)
- Typical tasks: two-step conversion; choose aq vs alc KOH; distil vs reflux; name a test for the product; one-carbon step with CN- (with hazard word).
- 1. PLAN
- Count carbons.
- 2. CHECK
- Br2, Tollens, carbonate, iodoform, AgNO3 as needed.
Overview
Plan, then check:
Plan
Count carbons. Find the group. Pick aq/alc, distil/reflux. Write reagents by the arrows. Mention catalyst names (H2SO4, Ni). Retro: draw precursor and one reagent arrow to target.
Examples Same C: ox or add · +1 C: CN- · Alkene hub
Check
Br2, Tollens, carbonate, iodoform, AgNO3 as needed. Yield < 100% sentence if asked. Hazard word for CN- / dichromate / conc acid. Test: state which functional group confirms success.
Examples Mirror · Fizz · Fade Br2
WHAT — EXAM RESPONSE (SYNTHESIS)
Typical tasks: two-step conversion; choose aq vs alc KOH; distil vs reflux; name a test for the product; one-carbon step with CN- (with hazard word). Stay on the syllabus map. No extra reagents from the internet. Forward route: numbered steps with reagents and structures. Count carbons after each synthetic step; silent carbon loss is the most common multi-step mistake.
WHY — Why this topic matters
EXAM RESPONSE (SYNTHESIS) is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
PLAN: Count carbons. Find the group. Pick aq/alc, distil/reflux. Write reagents by the arrows. Mention catalyst names (H2SO4, Ni). Retro: draw precursor and one reagent arrow to target. Examples: Same C: ox or add; +1 C: CN-; Alkene hub. CHECK: Br2, Tollens, carbonate, iodoform, AgNO3 as needed. Yield < 100% sentence if asked. Hazard word for CN- / dichromate / conc acid. Test: state which functional group confirms success. Examples: Mirror; Fizz; Fade Br2. Worked 4-mark ethene to ethyl ethanoate: hydrate -> ethanol oxidise reflux -> ethanoic acid ethanol + ethanoic, H2SO4 -> ester fruity named; school only Check carbon count each step — common error is losing or gaining a C silently.
Worked example
- Worked 4-mark ethene to ethyl ethanoate:
- hydrate -> ethanol
- oxidise reflux -> ethanoic acid
- ethanol + ethanoic, H2SO4 -> ester
- fruity named; school only
- Check carbon count each step — common error is losing or gaining a C silently.
In simple words
Synthesis exams. No illicit, no pharma manufacture, no explosives.
Key points
- two named arrows
- then a test
- count C first
- one confirm test
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Exam Response (synthesis)
Sticky Notes · Quick Revision
Core Idea
- Typical tasks: two-step conversion; choose aq vs alc KOH; distil vs reflux; name a test for the product; one-carbon step with CN- (with hazard word). Stay on the syllabus map. No extra reagents from the internet. Forward route: numbered steps with reagents and structures. Count carbons after each synthetic step; silent carbon loss is the most common multi-step mistake.
1. PLAN
- Count carbons. Find the group. Pick aq/alc, distil/reflux. Write reagents by the arrows. Mention catalyst names (H2SO4, Ni). Retro: draw precursor and one reagent arrow to target.
- Same C: ox or add
- +1 C: CN-
- Alkene hub
2. CHECK
- Br2, Tollens, carbonate, iodoform, AgNO3 as needed. Yield < 100% sentence if asked. Hazard word for CN- / dichromate / conc acid. Test: state which functional group confirms success.
- Mirror
- Fizz
- Fade Br2
Exam Example
- Worked 4-mark ethene to ethyl ethanoate:
- hydrate -> ethanol
- oxidise reflux -> ethanoic acid
- ethanol + ethanoic, H2SO4 -> ester
- fruity named; school only
- Check carbon count each step — common error is losing or gaining a C silently.
Common Misconceptions
- Do not confuse 1. PLAN with 2. CHECK; state the difference before giving an example.
- Writing only “two named arrows” is not enough. Explain what it means in a complete sentence.
FBISE Exam Check
- Explain exam response (synthesis), compare its two main parts, and include the correct chemical evidence.
- Synthesis exams. No illicit, no pharma manufacture, no explosives.
60-second revision
- Typical tasks: two-step conversion; choose aq vs alc KOH; distil vs reflux; name a test for the product; one-carbon step with CN- (with hazard word).
- 1. PLAN: Count carbons.
- 2. CHECK: Br2, Tollens, carbonate, iodoform, AgNO3 as needed.
- Exam reminder: Worked 4-mark ethene to ethyl ethanoate: hydrate -> ethanol oxidise reflux -> ethanoic acid ethanol + ethanoic, H2SO4 -> ester fruity named; school only Check carbon count each step — common error is losing or gaining a C silently.
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