amines, amino acids and polymers

week 10, question 5

primary amines

-NH₂

secondary amines

R-NH-R

physical properties of amines

• can form h bonds

• weaker than alcs

• higher bp than alkanes

• lower bp than alcs

• small R groups are soluble

chemical properties of amines

• amines are bases

• bronsted-lowry base = H+ acceptor

• lewis base behaviour = donates e- pair

• nucleophile

general formula of amino acids

RCH(NH₂)COOH

physical properties of amino acids

• relatively high mp = decompose before they melt

• relatively high bp = form zwitterion

zwitterion

• compound with no overall electric charge

• contains separate parts which are positively and negatively charged

solubility of amino acids

• soluble in water = smaller R group = more soluble

• insoluble in organic solvents = bc non polar

amino acids at pH 12

COO-

amino acids at pH 2

NH3+

amino acids at pH 7

NH3+ COO-

reaction of amine group in aas

• protonated by acids

• alkylation with acyl chloride (nuc +-)

• nuc sub with halo alkanes

reaction of carboxys in aas

• deprotonated by bases

• esterification with alcohols (acid catalyst)

stereoisomers

same structural formula different arrangement of atoms in space

optical isomerism

• chiral carbon present

• 2 molecular shapes that are superimposable

addition polymerisation

monomers bond to form long chained polymers (reaction)

polymer

long chain molecule made up of many repeating units

monomer

small reactive molecules that react together to form a polymer

condensation polymers

• elimination of a small molecule (H2O, HCl)

• polymer produced by repeated condesation reactions

• monomers linked by ester or amide bonds

dipeptide

2 amino acids and elimination of water molecule

acid hydrolysis

• H+ catalyst

• polyamide to dicarboxy + diammonium ions

alkaline hydrolysis

• heated with OH-

• polyamide to sodium salt + diamine