Question

9. Chlorine, bromine and iodine all react with alkenes such as ethene in an addition reaction. (a) Write the equation for the bromination of ethene, and name the product. (b) Explain why this is called an addition reaction. (c) Describe what you would see if you bubbled ethene through a solution of bromine in an organic solvent such as hexane. 10. If you use a permanganate test to distinguish between cyclohexane and cyclohexene, in which would the purple color of KMNO4 persist? 11. Only one aldehyde and only one primary alcohol gives positive iodoform test. What are their structures? 12. Which of the following compounds would give a positive iodoform test? i Yes/No (c) Yes No (a) (d) (b) Yes/No Yes/No

Answer 1

Ans. 9 @ Bromination of ethene and naming of produd CH2=CH2 + Bry CH₂ - CH2 1 Br Br 1-2-dibromoethane Ethene Promine (product 16 This reaction is electrophilic addition example mechanism. of CH₂ = CHO CH₂ - C 6+ Br 5 Br ta induced dipole Bys-2

CH2 CH2 Br Br and simple mechanism of addition Boomine is very polarizable moleculo approaching pe bond in ethene induces in dipple in bromine moleculo. It happens by electrophilie addition mélanum © Reaction with Bromine happenis at room temperature, etlene is bubbled through a pure liquid bromine colection 4 obroning in an organic solvent reddish brown bromine decolourssed as it reacts with the alkene of or a is