A2 OCR Chemistry B F334 - June 2015

Thanks! One question though, how come it wouldn't allow just the NH2 in the amide to be protonated? It only allowed the amine To be protonated

Thanks! One question though, how come it wouldn't allow just the NH2 in the amide to be protonated? It only allowed the amine To be protonated

its because amino acids can exist as zwitterions so only affects the -COOH group or amine group of an amino acid. the other amine group was from an amide

If you were to think of a general structure of the amino acid the amide bit is part of the R group.

Oh right, thanks!
But say if it were in high acid concentration, then the NH2 in the amide would also be protonated too?

Oh right, thanks!
But say if it were in high acid concentration, then the NH2 in the amide would also be protonated too?

Yh and I would expect the COO- on the zwitterion to also be protonated. Actually Im starting to doubt an amide can be protonated in a similar way to an amine. They are most likely far weaker bases. This might need some research.

' It should be noted that while amides are considered to be non-acidic and non-basic underphysiologic conditions, this functional group can be "protonated" (act as a base) or unprotonated(act as an acid) under more extreme chemical conditions. amides may be at least partially protonated and, in the presence of very strong bases, anamide hydrogen may be removed '
found from an online source.

is the hydrolysis of proteins the same conditions as hydrolysis of amides? so moderately concentrated NaOH heated under reflux ->carboxylate salts

What reagent/condition needed for ester hydrolysis?

dilute sulfuric acid heated under reflux

Nope, it's moderately concentrated, you lose the mark for dilute

Does anyone have/ know of any good revision notes? I need an A in chemistry and am really struggling with the A2 papers

What's the mark scheme specific definition for glass transition temperature?

Hey all, had a few questions which I found a bit strange.

June 2013 Q1cii)
The structure of A is -ooc(C6H4)coo- which I obtain correctly
The has formed from the carboxylic acid part of the molecule so should have a C=O bond peak at 1700-1725. However the markscheme says it should be at 1720-1740 (which would be an aldehyde!). But it also says reference to anything other than a carboxylic acid/carboxylate is a CON so it sort of contradicts itself. Any help?

Jan 2013 Q2a)
Why doesn't the hydroxyl group act as an acid? because don't OH groups deprotonate?