organic chemistry
- Created by: bambi
- Created on: 03-06-13 14:14
alcohols
mass spectrum - peak at 3230-3550
suffix-ol
contains oh functional group
can be formed by fermintation
Conditions for fermentation
* no oxygen as the reaction is anerobic
* yeast as a catalyst
* glucose(C6H1206)
* temperature of about 35-27 degrees is needed for enzymes to work
At low temperatures the reaction is slow at high temperatures the yeast dies so 35oc is a compromise temperature
Ethanol is produced
The difference between aldehydes and ketones
An aldyhyde has a hydrogen attached to c=o bond
Ketones do not have this hydrogen
A ketone must be attached to 2 carbohydrogen groups
The presence of the hydrogen atom makes aldhydes very easy to oxidise. Aldhydes are very strong reducing agents
Ketones are resistant to oxydation only very styrong oxidysing aggents such as potassium maganate solution can oxidise ketones
If an aldhyde is oxidisd under standard conditions a carboxylic acid will be formed
if an aldhyde is oxidised under alkaline conditions a salt of carboxylic acid is formed
regents to oxidise ketones
Acidified pottasium dicromate
Small amount of pottasium dichromate is acidified with dilute sulpuric acid (h2so4)
few drops of an aldhyde or ketone are added
if nothig happens the solution is warmed for a few minutes
Ketone - no change in the orange solution
Aldhyde- solution turns from orange to green
The orange dichromate ions have been reduced to green chronium ions by the aldhyde
The aldyhyde is oxidysed to a a carboxylic acid
Cr072-+ 14H+ +6e- = 2cr3+ +7H2O
RCHO+ H20= RCOOH + 2H+ + 2e-
The overall eqaution is
3RCHO + Cr2O72- + 8h+ = 3RCOOH +2Cr3+ +4H2O
Fehlings solution/ Benedicts reagent
Fehlings and benidicts varients of the same thing.
Fehlings solution contains copper2 ions complexed with tartrate ions in a sodium hydroxide solution
Complexing the tartrate iouns withy copper ions prevents the precipitation of copper hydroxide (Cu(Oh)2)
Benidicts regent contains copper2 ions mixed with citrate ions in a sodium hydroxide solution (Na(Oh)) prevents the formation of a a copper carbonate precipitate
Both reagents used in the same way Aldyhyde or ketone added to solution
Ketone_ no change in the blue solution
Aldhyde_ The blue solution produces a solid red precipitate of copper-1-oxide
ALDHYDES REDUCE COMPLEXED COPPER2+ TO COPPER-1-OXIDE. BECAUSE THE ALDHYDE IS OXYDISED IN A ALKALINE SOLUTION. A CARBOXYLIC SALT IS PRODUCED BY THE ALDHYDE
2cu+ in complex +OH- +2e- +cu2o + H2O
RCHO + 3Oh-= Rcoo- + 2h20 +2e-
The overall eqaution is
RCHO + 2Cu2+ in complex +RCOO- + cu2o + 3H20
Tollens reagent
tollens reagent contains {Ag(NH3)2]
This is made from silver nitate solution (AgNo3)
add sodium hydroxide to silver nitrate to give a precipate of silver oxide
add dilute ammonia to disolve the solution
to carry out test add Aldyhide of ketonr to solution
Ketone_ No change in the colourless solution
Aldehyde_the colourless solution pruduces a grey precipate of silver or a silver mirror on test tube
aldehydes reduce diammine silver ion to metalic silver .
. The solution is alkaline so a salt of carboxylic acid is produced
2Ag(NH3)2+ +e- = ag + 2Nh3
RCHO + 3OH- = RCOO- + 2H2O+ 2e-
The overall eqaution is
2Ag(NH3)2++ RCO+3OH-= 2Ag +RCOO- +4Nh3 +2H2O
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