Common Open-ended Qns in Organic Chem

1) Guide to Rxns ● Electrophilic ____ ○ C is e - rich which needs presence of C=C π bond (alkenes, arenes) ● Nucleophilic ____ ○ C is e - poor which means C is δ + (halogenoalkane, carbonyl) ● ____ addition ○ π bond is broken ● ____ substitution ○ σ bond is broken 2) Hybridisation a) describe sp 3 , sp 2 , sp hybridisation ● sp 3 hybridization involves one s and three p orbitals, resulting in four sp 3 hybrid orbitals and a tetrahedral geometry ● sp 2 hybridization uses one s and two p orbitals, creating three sp 2 hybrid orbitals and a trigonal planar geometry. ● sp hybridization combines one s and one p orbital to form two sp hybrid orbitals, leading to a linear geometry b) explain the shapes of, and bond angles in, the ethane, ethene, benzene, and ethyne molecules in relation to σ and π carbon-carbon bonds ● VSEPR: ○ To minimise electron repulsion, electron pairs arrange themselves as far apart as possible ○ lone pair lone pair repulsion > bond pair lone pair repulsion > bond pair bond pair repulsion 3) Isomerism a) describe constitutional (structural) isomerism ● Same molecular formula, different structural formula where atoms are connected differently b) describe conditions for cis-trans isomerism in alkenes, ● Restricted rotation around C=C bond and each C has 2 different groups attached to it c) explain what is meant by a chiral centre ● C atom bonded to 4 unique groups 4) Explaining Rxn Products a) Explaining production of racemic mixture ● Electrophile / Nucleophile can attack trigonal planar C / carbocation from either side of the plane with equal probability → both enantiomers are formed in equal concentrations → equal but opposite rotation of plane-polarised light results in net zero optical activity b) Theoretical ratio of mono-substituted products ● Assumes each H has equal chance of being substituted by X c) Why is XXX the major product? ● more ED alkyl groups → e - deficiency on carbocation / alkyl radical is reduced more → more stable carbocation / alkyl radical is formed preferentially

d) Difference in rate of formation of AgX ppt. ● Stronger bond strength → more time taken to form free halide ions → more time taken to observe ppt. 5) Explaining why Rxn occurs a) Why alkanes are generally unreactive ● the C–H bonds are non-polar (C and H have similar electronegativities) ● C − C and C − H bonds are rather strong b) Why alkenes can react with electrophiles ● The electrons are found in the regions above and below the plane of the