Flashcards · 9620 · AS Topic 19

Introduction to organic chemistry (AS Level) flashcards

14 cards on AS Topic 19, subtopics 3.3.1.1 to 3.3.1.3. Pick a subtopic or study them all.

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Homologous series: four features: Same general formula; successive members differ by CH₂; similar chemical reactions; a gradual trend in physical properties. All members contain the same functional group.
Functional group: The part of a molecule that is responsible for its typical chemical reactions.
Displayed, structural and skeletal formulae: Displayed: every atom and every bond drawn. Structural: groups written carbon by carbon, e.g. CH₃CH₂CHO. Skeletal: lines for bonds, carbons at ends and corners, no C–H hydrogens shown.
Name CH₃COCH(CH₃)CH₂CH₃: 3-methylpentan-2-one
Which functional groups are always on C1 and take no locant?: Aldehydes (-al) and carboxylic acids (-oic acid). Writing “butan-1-al” is wrong.

Radical: A species with an unpaired electron, shown by a dot (e.g. Cl•, CH₃•).
How are free-radical mechanisms written?: With no curly arrows: a balanced equation for each step, showing the radicals with dots.
Curly arrow: what does it show, and where does it start?: The movement of a pair of electrons. It starts from a lone pair or a covalent bond (the middle of the bond if the bond breaks) and points to where the pair goes.

Structural isomers: Compounds with the same molecular formula but a different structural formula.
Stereoisomers: Compounds with the same structural formula but a different arrangement of atoms in space.
Chain, position and functional group isomers (example pairs for C₆H₁₂O): Chain: hexanal and 2-methylpentanal. Position: hexan-2-one and hexan-3-one. Functional group: hexanal and hexan-3-one.
Cause of E–Z isomerism, and the condition for it: Restricted rotation about the planar C=C double bond. Each carbon of the C=C must carry two different groups.
E or Z: how do you decide using CIP priority rules?: On each C=C carbon, rank the two groups by the atomic number of the atom attached directly (compare further atoms if tied). Higher priorities on the same side = Z; on opposite sides = E.
Does 2,3-dimethylbut-2-ene have E–Z isomers?: No. Each carbon of the C=C carries two identical CH₃ groups.