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A2 1049
2-June-2016
ALDEHYDES
methanal
ethanal
propanal
3-methylbutanal
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A2 1049
2-June-2016
KETONES
propanone
butanone
pentan-3-one
4-methylpentan-2-one
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A2 1049
2-June-2016
OXIDATION & REDUCTION
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A2 1049
2-June-2016
OXIDATION & REDUCTION
• Tollen’s reagent, contains [Ag(NH3)2]+
• Used to test for aldehydes – gives silver mirror
• Reduced from Ag(+1) to Ag(0)
OXIDATION & REDUCTION
• Fehling’s solution, contains Cu(+2)
• Used to test for aldehydes – gives brick-red precipitate of Cu2O
• Reduced from Cu(+2) to Cu(+1)
OXIDATION & REDUCTION
• Acidified potassium dichromate, contains Cr2O72• Used to test for alcohols (1y and 2y) & aldehydes – goes from
orange Cr2O72- to green Cr3+
• Reduced from Cr(+6) to Cr(+3)
OXIDATION & REDUCTION
Distillation
Reflux
Aldehyde
condenses back
into reaction
mixture and
reacts further
Alcohols and carboxylic acids (have
hydrogen bonds between molecules)
have higher bpts than aldehydes – so
aldehyde can be distilled out as formed
NUCLEOPHILIC ADDITION
+
–
• Addition reactions: atoms add across C=O to the C and O
• C is + so attacked by nucleophiles (electron pair donors)
• The three atoms attached to the C are planar
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A2 1049
2-June-2016
NUCLEOPHILIC ADDITION
Reduction with NaBH4
+ 2[H]
H
_
:H
:
_
© www.chemsheets.co.uk
A2 1026
25-May-2016
NUCLEOPHILIC ADDITION
e.g. ethanal + NaBH4
+ 2[H]
+ 2[H]
H
_
_
:H
H
:H
:
_
:
_
© www.chemsheets.co.uk
A2 1026
25-May-2016
NUCLEOPHILIC ADDITION
e.g. propanone + NaBH4
+ 2[H]
+ 2[H]
H
_
H
_
:H
:H
:
_
:
_
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A2 1026
25-May-2016
NUCLEOPHILIC ADDITION
Reaction with KCN then acid
+ HCN
H
_
:CN
:
_
© www.chemsheets.co.uk
A2 1026
25-May-2016
NUCLEOPHILIC ADDITION
:CN
:CN
_
_
• many hydroxynitriles contain chiral C
• formed as racemic mixture (50/50 mixture of enantiomers)
• as equal chance of attack from above & below plane
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A2 1026
25-May-2016
:CN
:CN
_
_
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A2 1026
25-May-2016
NUCLEOPHILIC ADDITION
e.g. propanone + KCN then acid
+ HCN
+ HCN
H
_
H
_
:CN
:CN
:
_
:
_
© www.chemsheets.co.uk
A2 1026
25-May-2016
NUCLEOPHILIC ADDITION
e.g. propanal + KCN then acid
+ HCN
+ HCN
H
_
H
_
:CN
:CN
:
_
:
_
© www.chemsheets.co.uk
A2 1026
25-May-2016