amino acids Flashcards
draw an amino acid
H
|
(basic)H2N-C -COOH ( acidic)
|
R
What does the R group determine
- SIZE
- NAME
- POLARITY
there are 21 amino acids only one amino acid does not display optical isomerism why ?
only glycine does not display optical isomerism as its carbon centre does not have a chiral centre
why does amino acid have high melting points
as they can form hydrogen bonds
what is a zwitterion
a zwitterion ion has a negatively charged group (COO-) and a positively charged group (NH3+) . OVERALL in neutral conditions zwitterion is neutrally charged
why does it requite alot of energy to break 2 zwitterions
as they are formed via ionic bonds
how do zwitterions form
the amine group is a base as it accepts proton
the carboxylic acid group is an acid it donates protons
base properties of amines
the strongest base has the highest PH
why are aliphatic amines - NH2 are the strongest bases
they have more available lone pair . so can accept proton more readily
why are aromatic amines the weakest bases
the lone pair is less available as the 6p orbitals overlap to form a pi system contatining delocalised electrons .
the no of alky group bonded to nitrogen increases ________
the strength of the base increases
the no of benzene rings directly bonded to nitrogen increases _____
the strength of the base decreases
ammonia (NH3) lone pair allows it to act as a _____
NUCLEOPHILE
amine acts as _____
NUCLEOPHILE
in acidic condition only the amine (NH2) group changes to
NH3+
