(i) In the following pairs of halogen compounds, which would undergo SN1 reaction

faster? Explain.

(ii) Amongst the isomeric dihalobenzenes which isomer has the highest melting point and why?

(iii) Arrange the following haloalkanes in the increasing order of density. Justify your answer.

CCl4, CH2Cl2 and CHCl3.

(i)

• In SN₁ reactions the most important criterion for a compound to undergo this type of reaction is the formation of carbocation and its stability of the cation .

• Among the given 2 compounds chlorocyclohexane and chloromethyl cyclohexane , the chlorocyclohexane due to the possibility of hyperconjugation of the electrons from the C-H double bond where that carbocation is located foms more stable carbocation which unlikely for hence chlorocyclohexane undergoes SN₁ reactions in a much easier and faster way and is more suitable for elimination reactions due to unstability.

(ii)

• Among the dihalobenzenes always the para isomers have the highest boiling points amongst the other isomers.

• The reason is the symmetry of the para or 1,4 dihalobenzens which unlikely in the case of ortho or meta dihalobenzenes. This symmetry of the para isomer fits in the crystal lattice better compared to other isomers.

(iii)

• The correct increasing order of density of the haloalkanes is CH₂Cl₂>CHCl₃> CCl_{4 .}

• The reason behind this order is that, all of them has the same number ofm carbon atoms i.e. 2 but they differ in the number of halogen (Cl) atoms which is maximum in CCl₄ and minimumin CH₂Cl₂ which justifies the order.