NJC [Tutorial Answer] Introduction to Organic Chemistry

1Introduction to Organic Chemistry TutorialStructure and naming1Give the IUPAC name for each compound.(a)CH3CH(CH3)CH2CH(OH)CH34-methylpentan-2-ol(b)CH2=CHCH=CHBr1-bromobuta-1,3-diene(c)CH3Cl1-chloro-4-methylcyclohexane(d)CH3CH(CO2H)CH2CH32-methylbutanoic acid2Draw the skeletal formula of each compound.(a)2,2,4-trimethylhexane(b)2,4-dibromomethylbenzeneBrBr(c)1-ethyl-3,3-dimethylcyclopentane3For each part, the name given is incorrect. Draw the skeletal formula for each and give its correct IUPAC name.(a)2-ethylpentane3-methylhexane(b)2-chloro-2-ethylbut-3-ene3-chloro -3-methylpent -1-eneCl(c)2,3-diethylcyclopentane1,2-diethylcyclopentane(d)1,1-dimethy-3-propylhexane Hybridisation 4State the type of hybridisation of each carbon in each species.(a)CH3– sp3 (b)CH3CH2OH both sp3(c)CH3CHO sp3 and sp2(d)CH3+ sp2 (e)

C1 to C4 and C7: sp2; C5, C6 and C8: sp3Type of reaction5Classify each reaction as addition, elimination, condensation, oxidation, reduction or substitution.(a)CH3CH3 + Br2  CH2BrCH3 + HBrsubstitution(b)CH2=CHCH3 + Br2  BrCH2CH2BrCH3addition(c)CH3CH2CH2OH + 2[O]  CH3CH2CO2H + H2Ooxidation(d)CH3CO2H + 2[H]  CH3CHO + H2Oreduction(e)Cl COCH2CH3+ +HClOH OCOCH2CH3 condensation(f)+Cl HCl elimination6[N08/I/19]The bond lengths in buta-1,3-diene differ from those which might be expected. The carbon-carbon bond length in ethane is 0.154nm and in ethene is 0.134nm. The central single bond in buta-1,3-diene (C2-C3), however, is shorter than the single bond in ethane: it is 0.147nm. CH2CHCHCH212340.134nm0.134nm0.147nmWhat helps to explain this C2-C3 bond length?AIt is a sp2-sp2 overlap.BIt is a sp2-sp3 overlap.CThe electrons in the filled p orbitals on C2 and C3 repel each other.DThe sp3-sp3 bonding is pulled shorter by a p-p ( bond) overlap.In ethane, the carbons car sp3 hybridised, hence the single bond in ethane is formed from the overlap of sp3 hybrid orbitals; while in buta-1,3-diene, the carbons are sp2 hybridised, hence the C2 – C3 bond is formed from the overlap of sp2 hybrid orbitals. Since sp2 hybrid orbitals have higher s character, they are smaller and have greater degree of orbital overlap leading to a shorter bond length.

7Methanal has the molecular formula of HCHO and contains an unsaturated carbon. The C=O functional group of methanal can be described as being joined by a -bond and a -bond.(a)Identify the type of hybridisation of C in methanal. sp2(c)Hence, use a labelled diagram to show the orbitals that form the C=O bond in methanal.-bond is formed by the head-on overlap of sp2 hybridised orbitals of the C and the p orbital of O, or the of sp2 hybridised orbitals of the C and and O atoms -bond is formed by the sideways overlap of two p orbitals C and O atoms Remind students : -bond formation occurs only after a -bond is formed. bond bondOR bond bondBalancing equation for organic redox reaction 8Balance each equation with either [O] or [H]. Add H2O whenever necessary.(a)CH3CH2OH  CH3CHOCH3CH2OH +