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HL organic chemistry topic 20. More functional groups Amines NH 2 Draw 1-aminopropane (propanamine) and give condensed formula. Methylamine (old) aminomethane IUPAC 1,6-diaminohexane. 1-butylamine, 1-butanamine, 1-aminobutane (all the same). Secondary amines.
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HL organic chemistry topic 20 • More functional groups • Amines • NH2 • Draw 1-aminopropane (propanamine) and give condensed formula
Methylamine (old) aminomethane IUPAC • 1,6-diaminohexane
1-butylamine, 1-butanamine, 1-aminobutane (all the same)
Secondary amines • N-methylpropanamine (name the longest chain)
Tertiary amines • CH3CH2N(CH3)2 name and draw • N,N-dimethylpropanamine
Esters • Yeah, already done
Amides • R-CO-NH2 • Name the longest carbon chain followed by amide (amides on the end) • propanamide
Secondary amides • N-methylproanamide
Nitriles • R-CN • Used to be cyanides C2H5CN ethyl cyanide • Now propanenitrile • Draw it
Draw ethanenitrile • Pentanenitrile? • Do question 1
Nucleophilic substitution reactions • -ions or molecules with a nonbonding pair of electrons • Act as Lewis bases • Use curly arrows to show movement • H2O, OH-, CN-, NH3
SN2 mechanism • Ammonia and bromoethane forms ethylamine and hydrogen bromide • Need conc. NH3 and sealed tube for pressure
forms N-ethylethanamine then N,N-diethylethanamine • Eventually tetraethylammonium bromide
Needed for halogenoalkane reactions • Show bromoethane with potassium cyanide(in ethanol and reflux) to form propanenitrile • Show the SN2 mechanism
Factors affecting the rate of nucleophilic reactions • electronegative can easily donate e- pair • CN->OH- >NH3 > H2O • Strength of carbon to halogen bond remember I >Br to F
Type of mechanism SN1(tertiary) > secondary (mixture) > SN2 (primary) • Do question 2-5 • Lab activity • Do questions 17-19 page 399 for HW
Elimination reactions • Halogenoalkanes with hot NaOH in alcohol to alkene • With water and Br- also formed • C2H5Br to C2H4 • OH- in hot alcohol, reflux
E2 (elimination bimolecular)mechanism to form alkene • See pages 400 and 401 • Do questions 20-21 page 401 for HW
Condensation reactions • Acids and alcohols with H2SO4 as catalyst • H2O byproduct (makes a longer chain) • Pineapple is ethyl butanoate
Esters have no H bonding, are more volatile, less soluble in water • Naturally occurring fats and oils
Acids with primary amines form secondary amides • Ethanoic acid and metanamine
Secondary amines and acids form a peptide bond (tertiary amide) • Amino acids form peptide bonds
Alanine and glycine can form 2 dipeptides • Many amino acids form proteins
Do question 6-7 • Animation
Condensation polymerization • To make polypeptides or proteins • Hexane-1,6-dioic acid with 1,6-diaminohexane to form polyamide nylon
Polyesters like dacron • Benzene-1,4-dicarboxylic acid and ethane-1,2-diol draw this monomer (polyester) • PET is polyethene-1,4-benzoate used for plastic bottles • Do question 8 • Do questions 22-24 page 406 for HW
Reaction pathways • Add nitrile, amine and amide to your algorithms
Convert ethanol to N-methylethanamide using another organic compound • Do questions 25-27 page 407 for HW • Lab activity
Stereoisomerism • Same molecular and structural formula but atoms arranged differently in space
geometrical • Multiple bonds cannot be rotated • Cis trans • But-2-ene • Build this
Similar properties but not the same • Depends on the functional group • Polarity, shape and symmetry of the molecules
Cis and trans 1,2-dichlorethene • Which has the higher boiling point, melting point
Can occur in cyclic compounds • 1,2-dimethylcyclopropane cis and trans
5 isomers of dichlorocyclobutane • 2 are cis 2 are trans
Cis and trans-but-2-ene-1,4-dioic acid • trans strong H bonding mp 286 oC and cannot form cyclic anhydride
H bonding in molecule • cis mp 131 oC with heat trans can form cis-but-2-ene-1,4-dioic anhydride • lab activity
Optical isomerism • Asymmetric carbon atom (chiral) 4 different groups • Make a model of a chiral carbon and its stereoisomer • Mirror images = enantiomers • Do question 9
Drawings of enantiomers • Use an asterisk to designate the chiral carbon • Butan-2-ol
Draw the enantiomers of 2-hydroxypropanoic acid (lactic acid) Mark the chiral carbon atom and show the plane of the mirror
Demonstration of plane polarized light • Dextrorotatory d- rotated clockwise with a polarizor to get maximum intensity • Lavorotatory l- counter clockwise • Mixture of both is racemic • animations
Usually same chemical and physical properties • Exception is when they interact with other optically active substances • 2-amino acids must be l (-) form • Sugars d (+) form
Thalidomide in 1960’s • For morning sickness • One enantiomer causes malformations in the fetus
Do question 10-11 • Do questions 28-30 page 415 for HW • Do questions 12-17 on page 74 of your study guide • Do questions 13-20 pages 416-418 in your textbook