Amino Acids - Nitrogen Compounds Flashcards
What are amino acids?
Organic compounds containing amine + carboxylic acid functional group + side chain, which is specific to each amino acid
What is the general formula for amino acids?
RCH(NH2)COOH
How many amino acids is there?
20
How do you name amino acids?
Prefix = amino
Suffix = _anoic acid
Number carbon which NH2 is attached to
What is the name of CH3CH(NH2)COOH?
2 - amino propanoic acid
What is the name of C6H5CH2CH(NH2)COOH
2 - amino 3 - phenyl propanoic acid
What is the base group of an amino acid?
NH2
What is the acid group of an amino acid?
COOH
How is a zwitterion formed?
H from COOH is donated to NH2
What should the charge of a zwitterion be?
Neutral
When does a zwitterion form?
At isoelectric point
What is an isoelectric point?
pH at which an amino acid exists as a zwitterion
What happens to a zwitterion when pH increases
(H+ removed)?
H+ from NH3 is removed
Negative overall charge
What happens to a zwitterion when pH decreases (H+ donated)?
H+ donated to COO-
Positive overall charge
What is the isoelectric point affected by?
Different R groups
Draw zwitterion for alanine (CH3) and increase + decrease of pH
LOOK AT NOTES
Draw zwitterion for glutamic acid (CH2CH2COOH) and increase + decrease of pH
LOOK AT NOTES
Draw zwitterion for LYSINE ((CH2)4NH2) and increase + decrease of pH
LOOK AT NOTES
If you are increasing pH of a zwitterion that has COOH in its R group can you remove H+ from that as well?
YES
Which group can you only remove H+ from?
COOH
If you are decreasing pH of a zwitterion that has NH2 in its R group can you donate H+ to it as well?
YES
What happens when an amino acid reacts with an acid?
To NH2 to from NH3+
What is produced when CH3CH(NH2)COOH + HCl?
CH3CH(NH3+)COOHCl-
What happens when an amino acid reacts with an alkali?
Metal reacts with COOH to form COO-Na+
What is produced when CH3CH(NH2)COOH + NaOH?
CH3CH(NH2)COO-Na+ + H2O
What is the general formula when an amino acid + alcohol?
COOH part + alcohol ⇌ ester + H2O
What happens when an amino acid reacts with an alcohol?
OH from amino acid removed
H from alcohol removed
Join together to form ester
H2O produced too
What are the conditions needed for an amino acid reacting with an alcohol?
Heat
Strong acid catalyst - H2SO4
Reversible reaction
What is the problem sometimes with using H2SO4 as a strong acid catalyst when reacting an amino acid with an alcohol?
Sometimes donates H+ to NH2
What is produced when CH3CH(NH2)COOH + CH3OH?
CH3(NH2)COOCH3 + H2O
What is needed for a cis/trans isomer?
To have H as one of the groups
What is needed for a E/Z isomer?
C=C
2 different groups attached to each carbon
What is a stereoisomer?
Isomer that has the same structural + molecular formula but a different spatial arrangement of atoms
What is superimpose?
Place or lie over another and they are the exact same
What does it mean if two molecules are identical?
You can superimpose them
BUT they are not isomers
What does it mean if two molecules aren’t identical?
Cannot superimpose
So ARE isomers (stereoisomers)
What is optical isomerism?
2 isomers you can’t superimpose
What does an isomer have to have to be optical isomerism?
A carbon with 4 different groups attached
What is a chiral centre?
A carbon with 4 different groups attached
When identifying chiral centres what must you do?
Draw out displayed formula
Draw on all C’s and H’s
Identify with a star *
What is called when one molecule has one chiral centre and they mirror image each other?
Enantiomers
What is racemic mixture?
Both enantiomers in a mixture
If a molecule has 1 chiral centre, how many isomers does it have?
2
How do you find the other isomer of a molecule with one chiral centre?
Mirror image it
If a molecule has 2 chiral centres, how may isomers does it have?
4
How do you find the second isomer of an isomer with 2 chiral centres?
Mirror image the first
How do you find the third isomer of an isomer with 2 chiral centres?
Draw mirror image of top half of isomer 1 but keep bottom part the same
How do you find the fourth isomer of an isomer with 2 chiral centres?
Draw mirror image of bottom half of isomer 1 but keep top half the same
How do you know it is an alpha amino acid?
COOH + NH2 attached to same carbon