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Carbonyls
Organic A Level Chemistry 6.1.2…read more

Slide 2

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Alcohols are reducing agents in these
reactions
· Tertiary alcohols lacking a H on the
­OH carbon atom are NOT reducing
Brief AS Summary of Alcohols agents
· Functional group ­OH, CnH2n+1OH or ROH
· Oxidation potassium dichromate (VI) (K2Cr2O7 / Cr2O7 2-/H+)
acidified with dilute sulfuric acid : warmed with primary and secondary
alcohols (several drops) change the colour of the solution from orange to
green
· Primary initially oxidised to aldehydes- distil off as it is formed
excess oxidising agent and heat under reflux further oxidised
to a carboxylic acid
· Secondary oxidised to ketones which don't undergo further oxidation
· Tertiary resistant to oxidation, solution stays orange…read more

Slide 3

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Primary Alcohols, Oxidation Reactions
1) Oxidation of a primary alcohol under reflux aldehyde to a
carboxylic acid
2) Oxidation of a primary alcohol aldehyde…read more

Slide 4

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Aldehydes
· Contain the carbonyl functional group C=O
· The carbon atom attached to the carbonyl group contains 1 or 2 H atoms
· C=O is always found at the end of a Carbon chain
· In a structural formula, written as CHO
· Methanal is the simplest ­HCHO
· Used in solution to preserve biological specimens
Naming Aldehydes:
Remember to include
-count the no. of C atoms- name as the parent alkane alkyl groups e.g. `methyl'
-instead of `e' add `al' e.g. ethane ethanal…read more

Slide 5

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Ketones
· Contain the carbonyl functional group C=O
· The carbonyl functional group is joined to 2 Carbon atoms in the Carbon
chain
· In a structural formula, written as- CO
· The simplest ketone is propanone ­ CH3COCH3
· Used as an important industrial solvent, also used in nail varnish removers
Naming Ketones:
-count the number of C atoms- name as the parent alkane
-instead of `e' it ends in `one'
-number the lowest number carbon atom where the carbonyl group is
present e.g. pentan-2-one…read more

Slide 6

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Alkenes vs Carbonyls
· 2 types of bond that make up a double bond- pi bond: above and below
the plane of the molecule, sigma bond: between 2 adjacent atoms
· Pi bonds are weaker than sigma bonds
· The double bond in a carbonyl is unsymmetrical so electronegative and
polar, unlike the double bond in alkenes (non-polar)
· ^Oxygen is more electronegative than Carbon, so the electron density in
the double bond lies closer to the oxygen-slightly negative, than to the
carbon- slightly positive
· The C in the C=O may attract nucleophiles- it is attracted to and attacks
the slightly positive Carbon, resulting in addition across the C=O bond
· Mechanism by which alkenes react ­ electrophilic addition
· Mechanism by which carbonyls react- nucleophilic addition…read more

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