C-C BOND FORMATION Flashcards
What is C-C formation used for
for extending existing carbon chains
How is cyanide used in C-C formation and what happens
cyanide has a negatively charged carbon atom so is a NUCLEOPHILE, so can attack delta positive carbon atoms on a carbon chain (C-X)
CN substitutes the electronegative X group on a C-X bond
What is a nucleophile
it is an electron pair donor
Sources of Cyanide in synthesis
NaCN, HCN, KCN
How do haloalkanes react with Cyanide ions and what are conditions
Warm ethanol and KCN under reflux
CN- will attack the delta positive carbon and replaces the halogen, nucleophilic substitution
this forms a nitrile C
lll
N
halogen will form a bond with the potassium to give KX
Why are reactions done under reflux
if reactants are volatile so that reactants and products aren’t lost so a higher yield
How does KCN react with a carbonyl group
Produces hydroxynitriles
nucleophilic addition as CN- attacks the carbonyl group and adds on to make a hydroxy nitrile
can use HCN without acid but acid is needed with KCN to provide the H+ to bond with the oxygen as oxygen has a lone pair
How to form amines from nitriles
need to reduce nitriles using Hydrogen gas and a nickel catalyst
high temp and pressure
catalytic hydrogenation
makes a pure product of primary amines unlike using haloalkanes
another way of forming amines from nitriles
using a strong reducing agent such as LiAlH4 and dilute acid
more expensive than first method so uncommon to use in industry
reduction reaction, reducing agent 4[H] dissolved in a non aqueous solvent such as a dry ether
How to form amines from hydroxynitriles
reduction using LiAlH4 and dilute acid 4[H]
OH group is untouched but CN is reduced as it would in a nitrile to form CH2NH2
H2 with nickel catalyst and high temp and pressure
How to from carboxylic acids from nitriles
hydrolysing nitriles using dilute acid under reflux with water
the COOH carbon is from the CN
CN reacts with water to form an ammonium ion NH4+
How to form carboxylic acids from hydroxynitriles
same process as using nitrile, acid hydrolysis with water under reflux
however leaves a hydroxycarboxylic acid
Describe the process of friedel crafts alkylation
Forming alkyl benzene
React a haloalkane with a benzene using AlCl3 as a catalyst
done under reflux and has Hydrogen halide product
