Question

Please show the mechanism of the following reactions. Thank you so much in advance!

Не осн, H5C, осна H5C Br + HBr CH3OH 25 °C 50% 50% H,0 . + Br° . . ~ + снҳон 60 °C + ~ ~ о но Br Acetone 50 °C . . .ю° сьон Д. но во 60 °C . в . сноснон , нве HBr 75 °C

Answer 1

a) First one is the Nucleophilic substitution reaction type i.e SN1 .In such type of reaction first the leaving group leave then the carbocation form has two types of pathways (we marked as a and b) for the attack of nucleophile means one back side attack (a pathway) and other is front attack i.e b pathway.That why there is always a racemic mixture form(50:50 ) in the product.

b) This is the type of Elimination reaction i.e E2 means in a single step a anti beta hydrogen will remove by the base and at the same leaving group will remove to give a stable alkene.Generally strong base like OH- favours E2 elimination.

c) This is the type of Nucleophilic substitution reaction i.e SN2 which occurs in single step.Means a leaving group and a nucleophile get remove and attached respectively at the same time this stage is transition state in which bond breaking and bond formed in a same time.But there is stereochemistry involve that is always a inversion product formed.

d) This is E1 type elimination but this time a leaving group leaves first then a carbocation form followed by the removal of beta hydrogen to give desired alkene.

e) This is again E1 type elimination (generally favours by weak base) same a carbocation form and then removal of beta hydrogen by weak base then the formation of alkene takes place.

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Anso el Bro for o — -cm-cms 1524 I V + 810 + 487. CS Scanned with CamScanner