organic synthesis

Question 1

why is phenol more reactive than benzene?

Answer 1

1. lone pair of electrons on O atom
2. is donated to pi-system
3. making phenol more susceptible to electrophilic attack

Question 2

explain why compound is very soluble in water

Answer 2

compound forms H bonds with WATER

Question 3

structure and angle when theres 3 bonding pairs and one lone pair

Answer 3

pyramidal and 107

Question 4

structure and angle when 3 bonded regions and 0 lone pairs

Answer 4

trigonal planar and 120

Question 5

whats a chiral centre

Answer 5

atom which is bonded to 4 diff groups

Question 6

how to write an oxidising agent and reducing agen in an equation

Answer 6

ox.= [O]
reduc.= [H]

Question 7

methods to usefully process waste polymers

Answer 7

-recycling
-combustion for energy production
-use as organic feedstock for the production of plastics and other organic materials

Question 8

apparatus description for distillation

Answer 8

distillation flask
heat source
thermometer at outlet
still-head
water condenser
receiving vessel
open system- water in at collecting vessel end, water out at still-head end

Question 9

describe method to obtain pure sample from distillate/impure sample

Answer 9

shake and leave to settle in separating funnel
separate organic and aqueous layer- collect organic layer into separate beaker
add anhydrous salt CaCl2 to organic layer
fractional distillation of organic layer and collect fraction at certain temp.

Question 10

chemical test to identify ketone

Answer 10

react with 2,4-DNPH solution
recrystallise and determine m.p
compare m.p to known values

Question 11

3 methods to check a compounds purity

Answer 11

1. obtain m.p
   compare known values
   pure sample will have a sharp melting point very close to data book value
2. run an nmr/ir spec
   compare database- pure sample will contain same peaks but not others
3. run a TLC
   compare known Rf values- pure sample will have similar Rf value

Question 12

explain the trend for nitration of phenol, benzene, benzoic acid

Answer 12

reactivity decreases
phenol- lone pair of e- on O is donated/delocalised into pi-system
benzoic acid- COOH group is an e- withdrawing group

phenol has higher e- density so more susceptible to attack

Question 13

nitrile to COOH

Answer 13

aqueous acid - HCl

Question 14

why is a polymer which contains ester bonds biodegradable?

Answer 14

ester can be hydrolysed into COOH by dilute acid,heat