MO8 Carbonyl Containing Functional Groups Flashcards
What are the 6 carbonyl containing functional groups? Draw their structure
- aldehyde
- ketone
- amide
- amine
- carboxylic acid or carboxylate
- ester
Describe the structure of the carbonyl group
C=O
- C is delta +ve and O is delta -ve
- O is more electronegative than C so a larger share of bonded electrons go towards O, in addition to the 2x lone pairs of non-bonding electrons on the O.
Describe the properties of the carbonyl group
- the bond is NOT symmetrical
- the bond is polar due to the unevenly shared bonding electrons
- polar interactions = higher melting and boiling points
- good aqueous solubility as carbonyl O atom may H-bond with protic solvents increasing solubility
- nucleophilic attack of the electrophilic carbonyl carbon can occur
Is it more common for drugs to contain aldehydes or ketones? Why?
Ketones, not many drugs contain aldehydes because they are quite reactive.
Could a ketone have an intermolecular bond with itself? Why or why not?
No, because the C-H bond is not polarised enough to pull the bonding electrons enough to make H delta +ve enough to be attracted to the delta -ve O.
What are the 4 types of amides?
- Amide (1, 2 or 3* depending on the number of carbons directly attached to the nitrogen)
- lactam- a cyclic amide
- phosphonamide- amide with P=O instead of C=O
- sulphonamide- amide with S 2(=O)
What are the properties of amides?
- POLAR= hydrogen bond with polar solvents, good for improving water solubility
- chemically relatively unreactive therefore are chemically stable
- the non-bonding electron pair of the nitrogen is delocalised into the adjacent carbonyl group and so are 1. not good bases and 2. much LESS reactive towards nucleophiles at the carbonyl carbon than ketones, aldehydes and esters are.
Are amides stable:
-chemically?
-biologically?
- chemically yes as shared electrons in the amide bond makes the carbonyl group less electrophilic
- biologically not always… enzymes such as peptidases and amidases can enzymatically hydrolyse specific bonds
why are amides important for proteins?
they form the backbone of peptides and proteins. a peptide = amino acids with amide bonds connecting them. can form intramolecular H-bonds which are important for peptide and protein secondary structure.
what are the types of esters?
- normal ester
- thioester- sulphur instead of O
- lactone- cyclic ester
-carbamate- combination of an amine and an ester - inorganic ester- combination of an alcohol with an inorganic acid
what are the properties of esters?
- esters are polar due to the carbonyl group but can’t form intermolecular H bonds with itself.
- due to the polarised C=O bond and because the C-O bond can be broken, esters are prone to hydrolysis.
what is a prodrug?
a drug in an inactive or significantly less active form which is preferentially activated at the drug target
why might a prodrug be designed?
- can get across barriers some active drugs can’t
- decrease off target toxicity
- improve patient tolerance during administration, eg. improving the taste
- prolonged/slow release
what are the properties of thioesters?
- not commonly found in drugs but very important in metabolism, drugs with a CA are often metabolised via a reactive thioester intermediate.
- more reactive than esters and amides
