OC Ch 02 — 5-Minute Cram

Walking into the hall. Naming rules, conformation angles, chair rules, radical order. No "why" — just the numbers and order.

1. Five sentences you must know

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FormulaAlkane C_nH_2n+2; cycloalkane C_nH_2n. Both sp³, 109.5°, all single bonds.

Bond lengthsC–C 154 pm, C–H 110 pm.

EthaneStaggered > eclipsed by 12 kJ/mol. 99% staggered.

ButaneAnti (180°) > gauche (60°) > eclipsed (0° & 120°).

ChairBig substituent EQUATORIAL, NOT axial. 1,3-diaxial repulsion.

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C	1	2	3	4	5	6	7	8	9	10
Prefix	meth	eth	prop	but	pent	hex	hept	oct	non	dec

All end in-ane. Cycloalkane = cyclo prefix.

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1Find longest chain = parent.

2Name parent + "-ane".

3Number to give lowest locants.

4Write substituents with numbers.

5Alphabetise (di/tri don't count, except in complex sub names).

6Ring → "cyclo" prefix.

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1° / 2° / 3° / 4°Number of other carbons bonded to that C.

Radical order3° > 2° > 1° > methyl. Hyperconjugation.

BDE1° ~101, 2° ~98.5, 3° ~96.5 kcal/mol.

Radical shapesp², trigonal planar, unpaired e– in p orbital.

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InitCl₂ —UV→ 2 Cl·

Prop 1Cl· + CH₄ → HCl + CH₃·

Prop 2CH₃· + Cl₂ → CH₃Cl + Cl· (chain!)

Term2 Cl· → Cl₂ ; CH₃· + Cl· → CH₃Cl ; 2 CH₃· → C₂H₆

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F"Large substituent prefers axial." → EQUATORIAL.

T"Parent chain = longest continuous carbon chain." (alkanes)

T"Cyclopropane and propene can be distinguished by Br₂/CCl₄."

F"Monohydric alcohols can be 1°/2°/3°/4°." → 4° has no H, so no 4° alcohol.

McMurry & Ballantine 8e Ch 13 · TMU Slide pp.1–65 · Past Papers 2019–2022