Teaching Dossier for Chem 250, T. Sereda, 2010
Page 1 of 9
TERRANCE SEREDA
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
Expt #
Title of Experiment
1
Thermometer Calibration
Recyrstallization and Melting Points
(Principle of recrystallization, mixed melting points.)
Trimyristin from Nutmeg
(Extraction of a naturally occurring substance.)
The Separation of Benzoic Acid, Naphthaline and p-Chloroanailine
(Isolation of an acidic, basic and neutral compound.)
Akanes, Alkenes and Aromatic Hydrocarbons
(Preparation of cyclohexene, reactions of Br and permanganate.)
Adipic Acid from Cyclohexene
(Preparation of adipic via oxidation of cyclohexene.)
The Diels – Alder Reaction
(Preparation of a Diels-Alder product.)
Synthetic Polymers
(Preparation of a series of different polymer types.)
Friedel Crafts Reaction
(Preparation of p-di-t-butylbenzene.)
Nucleophilic Substitution Reaction
(Preparation of n-butyl bromide.)
Grignard Reaction
(Preparation of triphenylcarbinol.)
Oil of Wintergreen to Aspirin
(Preparation of aspirin from methyl salicylate.)
Solubility Tests & Functional Group Tests
(Principles of solubility in H2O, acid and base; functional group tests to aid in
identification of a compound.)
Identification of 3 unknown compounds using solubility, functional group testing and
infared spectrums.)
2
3
4/5
6
7
9
10
11
12
13
14
15
16-19
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
Expt #1:
-
Calibration of thermometer
calibrate thermometer due to fact that individual thermometer can be in error by a couple of
degrees
determine the melting temperature for 5 selected components of known melting point
plot the observed melting point versus the reference melting point
plot then used for accurate melting point determination
Teaching Dossier for Chem 250, T. Sereda, 2010
Page 2 of 9
TERRANCE SEREDA
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
Expt #2:
-
-
recrystallize (purify) crude benzoic acid from water
add enough water to create a slurry
heat to dissolve, filter insolube material
allow to cool for crystallization
calculation of percent recovery of recrystallized benzoic acid
determination of melting point to determine purity
mixed melting points for the identification of an unknown
mix unknown with known compounds, perform melting point
narrow melting point identifies unknown
Expt #3:
-
Recyrstallization and Melting Points
Trimyristin from Nutmeg
extraction of trimyristin from nutmeg via refluxing with dichloromethane
distillation of extracted solution to remove dichloromethane
recrystallization (purification step) of trimyristin from acetone
solubility (miscible and immiscible liquids):
for a series of mixtures of liquids, determine if miscible or immiscible
e.g.: ether/water immiscible; dichloromethane/water – immiscible; toluene/water –
immiscible; ether/dichloromethane – miscible, methanol/water – miscible,
methanol/acetone – miscible
general scheme: hydrocarbons – benzene – ether – alcohol – water
(adjacent are miscible); (acetone is miscible with alcohols and ether)
identify upper and lower layers for immiscible mixtures, based on density of liquid
Expt #4 & 5: The Separation of Benzoic Acid, Naphthaline and p-Chloroanailine
-
-
-
separation of three compounds which are all insoluble in cold water
solution of benzoic acid, p-Chloroanailine and Naphthaline dissolved in dichloromethane is
the starting sample
extract benzoic acid using an aqueous solution of NaOH
forms the Na salt of benzoic acid, which is soluble in the aqueous layer
isolation of benzoic acid: re-acidify the aqueous solution of Na salt of benzoic acid
recrsytallize benzoic acid
extract p-Chloroanailine using an aqueous solution of HCl
forms the Cl salt of p-Chloroanailine, which is soluble in the aqueous layer
isolation of p-Chloroanailine: extract with dichloromethane and evaporate – salt
dissolve salt in NaOH – back to p-Chloroanailine
extract with dichloromethane, evaporate, recrystallize
Naphthaline remains in the dichloromethane layer
distil off dichloromethane
purify by sublimation (solid – gas)
Teaching Dossier for Chem 250, T. Sereda, 2010
Page 3 of 9
TERRANCE SEREDA
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
Expt #6:
-
-
prepare cyclohexene by dehydration of cyclohexanol {E1 reaction}
acidify cyclohexanol with phosphoric acid
distil crude cyclohexene, wash with water to remove cyclohexanol/phosphoric acid
distil cyclohexene
reactions alkanes, alkenes and aromatic hydrocarbons
alkanes:
free radical substitution in the presence of light, e.g., halogenation;
not oxidized by permanganate
alkenes:
electrophilic addition reaction, e.g., addition of Br2 across alkene;
successive oxidation of alkene by permanganate
(alkene → alcohol → acid; cleaves alkene)
aromatic hydrocarbons:
stable to both types of reactions
Expt #7:
-
-
The Diels – Alder Reaction
a cyclo-addition reaction of 1,3 – diene and a dienophile
specific reaction is between 1,3-butadiene and maleic anhydride
1,3-butadiene is generated from butadiene sulfone upon heating
reflux the reactants in xylene
recrystallize from hexane
Expt #10:
-
Adipic Acid from Cyclohexene
complete oxidation of cyclohexene to the carboxylic acid (adipic acid)
HOOC-CH2- CH2- CH2- CH2-COOH
add aqueous permanganate to cyclohexene
basify to make Na salt, filter
acidify to return to carboxylic acid, recrystallize
Expt #9:
-
Alkanes, Alkenes and Aromatic Hydrocarbons
Synthetic Polymers
preparation of polymers (resins) from monomers
phenolic:
phenol + formaldehyde (all possible o-, p- substitutions), results in
phenols cross linked by methylene groups
urea-formaldehyde: results in urea group covalently linked via a methylene group
polyesters:
anhydride + diol (e.g. phthalic anhydride + ethylene glycol),
results in benzyl covalently linked via an ethyl group and ester
vinyl polymers:
free radical polymerization of methyl methacrylate to produce
plexiglass, proceeds through the carbon-carbon double bond
functionality (other example polyethylene), need initiator
polyamides:
reaction of a di-acid chloride with diamine, e.g., Nylon 6-10
sebacyl(8) Cl + hexamethylenediamine
subsequent description of resin formed
Teaching Dossier for Chem 250, T. Sereda, 2010
Page 4 of 9
TERRANCE SEREDA
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
Expt #11:
-
-
electrophilic aromatic substitution reaction
AlCl3 reagent is a Lewis acid (accepts e- pair) – generates a carbonium ion on the alkyl
halide
carbonium ion is electrophilic and attacks the double bond of benzene
aromatic + alkyl halide = alkyl substitution reaction
benzene + t-butyl chloride → p-di-t-butylbenzene
Expt #12:
-
-
-
-
Grignard Reaction
reaction of a Grignard reagent (organomagnesium halide) with a carbonyl compound – as a
way to form new carbon-carbon bonds
preparation of the Grignard reagent: react aryl halide with Mg
(must be done in absence of either water or oxygen (reason for using ether))
bromobenzene + Mg → phenylmagnesium bromide
the carbon atom of benzene bears a negative charge; thus, is a good nucleophile
react phenylmagnesium bromide with benzophenone → triphenol carbinol
Expt #14:
-
Nucleophilic Substitution Reaction
general reaction: R-OH + HX → R-X + H2O
preparation of 1-bromobutane
nucleophilic substitution reaction: the primary alcohol is protonated with acid which makes
it a good leaving group and is displaced with the nucleophile Brthus is an SN2 reaction due to the fact that the alcohol is primary alcohol
n-butyl alcohol + H+ + NaBr → 1-bromobutane
reaction proceeds through the in-situ formation of HBr from NaBr and sulfuric acid
Expt #13:
-
Friedel Crafts Reaction
Oil of Wintergreen to Aspirin
conversion of methyl salicylate to aspirin (2-acetoxybenzoic acid;
acetylsalicylic acid)
base hydrolysis of the ester methyl salicylate to form salicylic acid (2-hydroxybenzoic acid)
acetylation of salicylic acid with acetic anhydride:
acid anhydride reacts with alcohol functionality to form an ester (i.e., acid anhydrides are a
mechanism for introducing an acyl group into compounds that have a good nucleophile)
Teaching Dossier for Chem 250, T. Sereda, 2010
Page 5 of 9
TERRANCE SEREDA
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
Expt #15:
Solubility Tests & Functional Group Tests
-
test the solubility of 2-propanol, benzoic acid, aniline, 2-nahthalene
in hot and cold water (test pH)
in NaOH (to distinguish acidic compounds)
in HCl (to distinguish basic compounds)
saturated KHCO3 distinguish between carboxylic acids{S} and phenols{I})
-
functional group tests:
2,4-DNP: for carbonyl groups in aldehydes, ketones; red-yellow ppt
Tollen’s: for aldehydes; get silver mirror (Ag ppt)
ferric chloride, FeCl3: for phenols; colored complexes – red, purple, blue,
green
ferric hydroxamate (hydroxylamine + ferric Cl): for esters; purple color
ferrous hydroxide, Fe(OH2): for aromatic nitro compounds; a color change
from blue to brown {oxid/red rxn: ferrous hydroxide → ferric hydroxide}
Pauly test: for phenols and aromatic amines; forms colored compounds
Hinsberg test: for 1°, 2° and 3° aliphatic amines: differential solubility in NaOH,
HCl; NaOH
Expt #16-19: Identification of 3 unknown compounds
-
identification of three unknown organic compounds
determination of melting point or boiling point
solubility testing in water, NaOH, HCl; if appropriate – pH or saturated KHCO3
functional group tests
perform infared spectrum and analysis of functional groups:
general:
-
4000-2500
1800-1650
1650-1550
1300-1000
→
→
→
→
O-H, N-H, C-H, COOH
C=O
C=C
C–O, C–N
characteristic absorptions give in table below:
Page 6 of 9
Teaching Dossier for Chem 250, T. Sereda, 2010
TERRANCE SEREDA
Labs taught in Organic Chemistry (Chem 250) at Red Deer College
1
Compound
alkanes
2
alkenes
3
Aromatic rings
4
Alcohols
5
6
Ethers
Carbonyl group
7
8
9
Aldehydes
Ketones
Carboxylic acids
10
Esters
11
Amine
Functional Group
CH aliphatic
CH2
CH3
CH aliphatic
C=C
C=C, conjugated
aromatic C=C
aliphatic CH
Aromatic CH
m-, o-, p- substitutions
=CH out of plane
free O–H
Hydrogen bonded O–H
C-O
phenol C-O
3° alcohol, C–O
2° alcohol, C–O
1° alcohol, C–O
C–O
C=O, anhydride
C=O, ester
C=O, aldehyde
C=O, ketone
C=O, carboxylic acid
C=O, amide
C-H, aldehyde H (-CHO)
C=O
Hydrogen bonded O–H
C=O
C–O
C=O
C–O
N–H for 1° and 2°
N–H for 1°
N–H for 2°
C–N, aliphatic amine
C–N, aromatic amine
cm-1
3000-2800
1450
1375
3000-2800
1660-1600
1600-1400
1600& 1475
2800-3000
> 3000
2000-1700
800-700
3650-3600, sharp
3500-3200, broad
1250-1000
1220
1150
1100
1050
1300-1000
1760
1735
1725
1715
1710
1690
2850 & 2750
1745-1665
3400-2400, broad
1730-1700
1320-1210
1735
1300-1000
3500-3300
1640-1560
1500
1250-1000
1350-1250
Page 7 of 9
Teaching Dossier for Chem 250, T. Sereda, 2010
APPENDIX
1.
TERRANCE SEREDA
Recyrstallization solvents:
Non-Flammable:
Water, CCl4
Flammable:
Ether, Acetone, benzene
Impurities cause MP depression, BP elevation.
2.
Distillation:
If > 80 ºC difference in boiling point, may be separated by simple distillation.
If 30 – 80 ºC difference in boiling point, may be separated by repeated simple distillation.
Can evaporate under a vacuum if BP < 50 ºC.
If Immiscible – will co-distill.
Steam distillation – co-distills at a temp < than the BP of either liquid.
If an oil forms after distillation, then the solute has a MP < BP of the solvent.
Azeotrope – liquid and vapour has the same composition (thus can not separate by
distillation). Boils at a constant temp.
e.g.
HCl = -80 ºC, H2O = 100 ºC; azeotrope @ 20% H2O boils at 108 ºC
ethanol = 78.5 ºC, H2O = 100 ºC; azeotrope @ 4% H2O boils at 78 ºC
3.
Electrophile – likes electrons; thus, is positively charged
Nucleophile – likes nucleus; thus, is negatively charged; {Z: or Z ; Nu: or Nu }
4.
Nucleophilic Substitution Reaction:
SN1 reaction – based on most stable carbonium ion (carbocations).
SN2 reaction (concerted, bimolecular) – based on steric hinderance.
Examples:
-
-
-
-
OH is the nucleophile and Cl , Br , I is the leaving group.
- +
Cl , Br , I is the nucleophile and OH2 is the leaving group.
5.
Elimination Reaction:
Formation of C=C double bonds
1,2 elimination – dehydration of alcohols or dehydrohalogenation
E1 reaction – based on most stable carbonium ion:
E2 reaction (concerted, bimolecular) – based on steric hinderance:
6.
Electrophilic Addition Reaction, to a double bond: (HBr, Br2)
Br or H become polarized, δ+, thus is an electrophile
Electron pair from C=C forms bond Br/H, subsequent formation of a carbonium ion
Or {form an intermediate with Br, i.e., the bromonium ion}
7.
Miscibility:
general scheme: hydrocarbons – benzene – ether – alcohol – water
Note: acetone is ∞ soluble in benzene, ether, alcohol, water
Note: dioxane is ∞ soluble in benzene, ether, alcohol, water
Note: Methylene Chloride (CH2Cl2) is soluble in ether, alcohol
Teaching Dossier for Chem 250, T. Sereda, 2010
APPENDIX
8.
TERRANCE SEREDA
Oxidation:
Reduction:
loss of electrons (e –); adding oxygen or removing hydrogen
gain of electrons (e –); adding hydrogen or removing oxygen
Oxidation:
R2CH – OH → R2C = O (ketone)
RCH2 – OH → RCH = O (aldehyde) → RC(OH) = O carboxylic acid
Is just the reverse reaction.
Reduction:
9.
NMR:
1.
chemical shift (δ) in ppm scale – relative to TMS = 0 ppm
2.
(12)-------------------------------------------(0), TMS
Down field
Up field
Least shielded
Most shielded
3.
14,000 magnetic field = 60 MHz spectrometer
If a resonance occurs at 600 MHz, then 600/60 = 10 ppm
4.
Integration:
55.5 divisions
22 divisions
32.5 divisins
5.
6.
10.
Page 8 of 9
55.5/22
22/22
32.5/22
2.5
1.0
1.4
multiply by a factor of 2
5.0
2.0
2.8
Ratio: 5:2:3 protons
Splitting patterns: neighbors +1 = (n + 1)
e.g.
CHa – CHb CHc
Ha
will show up as 2+1 = 3 peaks (triplet)
CHb CHc
will show up as 1+1 = 2 peaks (doublet)
Chemical shift (δ) values for groups:
0 – 2 ppm
methine, methylene, methyl
2 – 3 ppm
CH2 – Ar, H–C ≡ C {ethynyl}, CH2 – (C=O) – ,
CH2 – C=C – {allyl}
3 – 5 ppm
CH2 – Br{halide}, CH2 – O
0 – 5 ppm
alcohols, (– OH), amines (– NH)
5 – 7 ppm
– C=CH – H {vinyl}
7 – 8 ppm
phenyl
9 – 10 ppm aldehyde
10 – 12 ppm carboxylic acid
Grignard Reactions:
1.
Ra – Br + Mg → Ra(δ- ) – (δ+ ) MgBr + R2 – C = O → R2 (–Ra) – C – OMgBr
R2 (–Ra) – C – OMgBr + H+ → R2 (–Ra) – C – OH
2.
Grignard + Ketone → 3º alcohol
Grignard + Aldehyde → 2º alcohol
Teaching Dossier for Chem 250, T. Sereda, 2010
APPENDIX
11.
Page 9 of 9
TERRANCE SEREDA
1.
Fischer Esterification: (nucleophilc substitution)
Carboxylic acid + Alcohol + H+ → Ester
Acid anhydride + Alcohol → Ester
2
Expt 14:
12.
1.
2.
Friedel Crafts – elctrophilc aromatic substitution.
Nitration of aromatic compounds – elctrophilc aromatic substitution.
H2SO4 + HNO3 → +NO2 {which is the electrophile}, {benzene is nucleophile}
13.
Alkyl group {R – }
Acyl group {R – C(=O) –}
14.
Petroleum Ether:
Ligroin(Light Naphtha):
15.
Atm pressure = 760 torr (mm Hg)
Edmonton is approx 700 torr
16.
1.
2.
3.
Convert ester to carboxylic acid using (OH–).
OH group converted to ester using acetic ahhydride.
C5 – C6, BP = 20-60 ºC.
C6 – C7, BP = 60-100 ºC.
Hexane + Br + hν → halogenated hydrocarbons (purple to brown)
Hexane + Br + dark → No Reaction
Hexane + MnO4- → No Reaction