Aldehydes And Ketones Flashcards
(11 cards)
Aldehydes What is the carbonyl linked to? What is it prepared by? How do you name them? How do you name them if they are attached to a benzene?
H
Oxidation of primary alcohols
End with al eg propanal
Benzene carbaldehyde
Ketones What is the carbonyl attached to? What are they prepared by? How do you name them? What do you name them when they are attached to a benzene? Cyclohexane?
Two carbons Oxidation of secondary alcohol End with one eg propan-2-one Phenylethanone Cyclohexanone
Physical Properties
What forces are present between molecules?
Why are these present?
What is bpt higher than and lower than?
What is methanal at room temp? What are the longer chains?
Which mix with water? How do they mix? Draw an example of how this works?
What does solubility decrease with?
Dipole dipole
Polarity of the C-O bond
Higher than alkanes lower than alcohols of similar Mr
A gas liquids
Shorter chains O of carbonyl forms hydrogen bonds with H of water
Increasing Chain length
Oxidation of aldehydes
Why are aldehydes readily oxidised to?
General equation
Carboxylic acids
RCHO + [O] > RCOOH
What are the three tests between aldehydes and ketones and what do you observe with each?
Which is easier and why?
K2Cr2O7 Al-orange>green one-no change
Fehlings al-brick red ppt one-no change
Tollens al-silver mirror one- no change
Mild oxidising agents
Reduction of Aldehydes and Ketones
What does it produces respectively?
What are the three ways?
Primary and secondary
Catalytic hydrogenation
Addition of a hydride ion
Addition of hydrogen cyanide
Catalytic hydrogenation Like what? What is it with? What is the catalyst and what is the temp? What happens to the hydrogen molecule? Where is it added? Draw equation with butanal Draw equation with prop-2-enal
Alkenes Hydrogen Nickel 200c Splitting H Added across C=C Add one hydrogen Add two hydrogen
Addition of Hydride Ion What is the hydride ion? What is open to attack? What's the reagent? In what? Example with propanone What supplies the second H+? Why can it be used selectively? Example with prop-2-enal
H:- C NaBH4 In aqueous ethanol CH3COCH3 + 2[H] > CH3CH(OH)CH3 Weak acid or water Has no effect on C=C CH2=CHCH=O+2[H]>CH2=CHCH2OH
What is the general formula?
CnH2nO
Addition of Hydrogen Cyanide
What does it form?
Why is it not done with HCN?
What is the reagent?
Equation with CH3CHO and HCN
What do all aldehydes except methanal and all unsymmetrical ketones react with HCN to form?
The product obtained is an?
What does this mean with regards to attack from cyanide?
What is the product useful in? What does it lengthen?
Hydroxynitrile Bc is toxic Sulphuric acid added to KCN CH3CHO+HCN>CH3CH(OH)CN Compounds with a chiral carbon Optically inactive racemic mixture Equally probability from either side Organic synthesis, carbon chain length
What can oxidise the C triple N bond? To what?
What can reduce the C triple N bond? To what?
What are these important?
Example of what is formed from CH3CH(OH)CN with both? Name both
Acid hydrolysis to COOH catalytic hydrogenation to CH2NH2 Important in organic synthesis CH3CH(OH)COOH 2-Hydroxypropanoic acid CH3CH(OH)CH2NH3 2-Hydroxypropylamine
