ChemistryChapter 19: Carbonyl Compounds
Nucleophilic Addition (school)
HCN addition named: forms a hydroxynitrile (cyanohydrin named).
Learning objectives
- Explain nucleophilic addition (school) in simple chemical language.
- Connect 1. hcn with 2. reduction using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Definition
HCN addition named: forms a hydroxynitrile (cyanohydrin named). HCN is toxic — teacher demo / closed system slogans, not a student how-to, and not a route to restricted products. Hydride named (NaBH4 / LiAlH4 as names): carbonyl to alcohol (aldehyde -> 1 alcohol, ketone -> 2). Meaning: Nu to C, then H to O (after). Curly arrows if asked. HCN, NaHSO3, alcohol hemiacetal, Grignard named — all add to C=O. Tollens distinguishes aldehyde from ketone; iodoform targets methyl carbonyl or ethanol specifically.
Formula
C=O. Tollens distinguishes aldehyde from k
Important terms
- NUCLEOPHILIC ADDITION (SCHOOL)
- HCN addition named: forms a hydroxynitrile (cyanohydrin named).
- 1. HCN
- KCN then dilute acid as some books write (safer wording than free HCN gas).
- 2. REDUCTION
- NaBH4 named mild.
Relationship
- Nu to C of C=O
Overview
HCN named, then hydride names:
Hcn
KCN then dilute acid as some books write (safer wording than free HCN gas). Product: extra carbon (step-up named). Toxicity: medical emergency if exposure, not a note-book treatment. No cyanide processes. Equilibrium favours addition for aldehydes over ketones (less steric hindrance).
Examples Hydroxynitrile named · Toxic slogan · Not a plant
Reduction
NaBH4 named mild. LiAlH4 named stronger (also reduces acids/esters if asked). H2 / Ni can reduce C=O too. Product class from aldehyde vs ketone. Cyanohydrin formation from HCN — name product not lab preparation.
Examples Ethanal -> ethanol · Propanone -> propan-2-ol · Names of reductants
WHAT — NUCLEOPHILIC ADDITION (SCHOOL)
HCN addition named: forms a hydroxynitrile (cyanohydrin named). HCN is toxic — teacher demo / closed system slogans, not a student how-to, and not a route to restricted products. Hydride named (NaBH4 / LiAlH4 as names): carbonyl to alcohol (aldehyde -> 1 alcohol, ketone -> 2). Meaning: Nu to C, then H to O (after). Curly arrows if asked. HCN, NaHSO3, alcohol hemiacetal, Grignard named — all add to C=O. Tollens distinguishes aldehyde from ketone; iodoform targets methyl carbonyl or ethanol specifically.
WHY — Why this topic matters
NUCLEOPHILIC ADDITION (SCHOOL) 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
HCN: KCN then dilute acid as some books write (safer wording than free HCN gas). Product: extra carbon (step-up named). Toxicity: medical emergency if exposure, not a note-book treatment. No cyanide processes. Equilibrium favours addition for aldehydes over ketones (less steric hindrance). Examples: Hydroxynitrile named; Toxic slogan; Not a plant. REDUCTION: NaBH4 named mild. LiAlH4 named stronger (also reduces acids/esters if asked). H2 / Ni can reduce C=O too. Product class from aldehyde vs ketone. Cyanohydrin formation from HCN — name product not lab preparation. Examples: Ethanal -> ethanol; Propanone -> propan-2-ol; Names of reductants. Exam reduction: aldehyde -> primary alcohol ketone -> secondary alcohol NaBH4 named; not a metal-hydride SOP
In simple words
Named additions. No HCN how-to, no cyanide manufacture.
Key points
- Nu to C of C=O
- reduction -> alcohol
- extra C
- H- to C
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Nucleophilic Addition (school)
Sticky Notes · Quick Revision
Core Idea
- HCN addition named: forms a hydroxynitrile (cyanohydrin named). HCN is toxic — teacher demo / closed system slogans, not a student how-to, and not a route to restricted products. Hydride named (NaBH4 / LiAlH4 as names): carbonyl to alcohol (aldehyde -> 1 alcohol, ketone -> 2). Meaning: Nu to C, then H to O (after). Curly arrows if asked. HCN, NaHSO3, alcohol hemiacetal, Grignard named — all add to C=O. Tollens distinguishes aldehyde from ketone; iodoform targets methyl carbonyl or ethanol specifically.
1. HCN
- KCN then dilute acid as some books write (safer wording than free HCN gas). Product: extra carbon (step-up named). Toxicity: medical emergency if exposure, not a note-book treatment. No cyanide processes. Equilibrium favours addition for aldehydes over ketones (less steric hindrance).
- Hydroxynitrile named
- Toxic slogan
- Not a plant
2. REDUCTION
- NaBH4 named mild. LiAlH4 named stronger (also reduces acids/esters if asked). H2 / Ni can reduce C=O too. Product class from aldehyde vs ketone. Cyanohydrin formation from HCN — name product not lab preparation.
- Ethanal -> ethanol
- Propanone -> propan-2-ol
- Names of reductants
Exam Example
- Exam reduction:
- aldehyde -> primary alcohol
- ketone -> secondary alcohol
- NaBH4 named; not a metal-hydride SOP
Common Misconceptions
- Do not confuse 1. HCN with 2. REDUCTION; state the difference before giving an example.
- Writing only “Nu to C of C=O” is not enough. Explain what it means in a complete sentence.
FBISE Exam Check
- Explain nucleophilic addition (school), compare its two main parts, and include the correct chemical evidence.
- Named additions. No HCN how-to, no cyanide manufacture.
60-second revision
- HCN addition named: forms a hydroxynitrile (cyanohydrin named).
- 1. HCN: KCN then dilute acid as some books write (safer wording than free HCN gas).
- 2. REDUCTION: NaBH4 named mild.
- Exam reminder: Exam reduction: aldehyde -> primary alcohol ketone -> secondary alcohol NaBH4 named; not a metal-hydride SOP
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