Organic chem II Flashcards
2-bromobutane and cyanide ions react together by Sn2 mechanism- Draw the structure of the transition state formed in this reaction
check 17.1.3 question 1
answers online
(edexcel alevel book 2 )
What is the functional group for an aldehyde
RCOH (hydrogen attached to carbonyl group)
How do we name aldehydes
- Count carbon chain
- Name molecule as if its an alkane
- Add “-al” to the end of it
With aldehydes how do we know which is carbon 1
Carbon 1 is always the carbon with the carbonyl group attached to it
What is the functional group for a ketone
RCOR (carbonyl group with 2 different groups also attached to it
How do we name ketones
- Count carbon chain
- Name molecule as if its an alkane
- Add “-one” to the end of it
Do ketones or aldehydes require locants? give reason for answers
Ketone - yes - as it can be placed anywhere in carbon chain
Aldehyde - rarely - as it tends to be placed on ends of molecules
What are the 2 carbonyl compounds
Ketones
Aldehydes
Why can’t carbonyl groups undergo hydrogen bonding?
As they don’t have a polar OH bond so they can’t form hydrogen bonds with other ketones or aldehydes
what kind of attack are carbonyl groups more susceptible too? and why?
Nucleophilic attack due to C=O polar bond nature (delta positive C, delta negative O)
State a few physical properties of Aldehydes
Small chain aldehydes = Unpleasant smells
Large chain aldehydes = Pleasant smells used in parfumes
which of these have the highest-lowest boiling point, and explain why?
alkane,alcohol,ketone&aldehyde
Highest - Lowest
alcohol, ketone&aldehyde, alkane
Alcohol - contain OH bond (as well as london and dipole interactions)so can undergo hydrogen bonding with other substances
Ketones&Aldehyde - london forces and dipole interaction - no hydrogen bonding with itself
Alkanes - weak intermolecular forces -London forces
Why is propanone soluble in water
Short chain ketone
Can form hydrogen bonds with water
what makes the carbon double bond in carbonyls polar
Oxygen is far more electronegative than carbon so has a strong tendency to pull electrons in a carbon-oxygen bond towards itself.
One of the two pairs of electrons in carbon-oxygen double bond is even more easily pulled towards the oxygen.
what are nucleophiles
Negative ion or negatively charged part of a molecule that donates lone pairs of electron to electron deficient atoms
why aren’t long chain aldehydes or ketones soluble in water
As chain lengths increase, the hydrogen bonding is interrupted by the rest of the hydrocarbon getting in
between water molecules,breaking the relatively strong hydrogen bonds between water molecules
how do ketones and aldehydes differ?
Aldehydes have a hydrogen attached to C=O bond which makes them more easily oxidised
ketones don’t have a hydrogen attached to C=O bond and so require strong oxidising agents
What state are majority of carbonyl groups at room temp
liquids due to relatively low melting and boiling points
Why does the boiling/melting point of carbonyl groups increase as the chain length increases
Larger the molecule= more london forces and therefore temporary dipole interactions
