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Classification test of organic compounds
mrsantiago (Chem 200 lab, AY 2014-2015)
Physical and chemical properties
Physical properties
• Physical state (solid, liquid, gas)
• Color, odor
• Solubility
Chemical properties
• Reaction to litmus paper
• Chemical tests
mrsantiago (Chem 200 lab, AY 2014-2015)
mrsantiago (Chem 200 lab, AY 2014-2015)
mrsantiago (Chem 200 lab, AY 2014-2015)
Solubility in water
mrsantiago (Chem 200 lab, AY 2014-2015)
mrsantiago (Chem 200 lab, AY 2014-2015)
mrsantiago (Chem 200 lab, AY 2014-2015)
mrsantiago (Chem 200 lab, AY 2014-2015)
Factors affecting H2O solubility
• Intermolecular forces of attxn
(H bonding>dipole>hydrophobic)
• No. of carbon atoms (>5C insoluble; C, hydrophobicity, less polar )
• Length of HC chain
• Branching (branching, length, hydrophobic)
• Presence of polar functional groups
mrsantiago (Chem 200 lab, AY 2014-2015)
FUNCTIONAL GROUPS THAT MAY CAUSE IMFA
• Functional groups that can participate in H-bonding – Carboxyl – Carbonyl – Hydroxyl – Amino
• Functional groups that can participate Dipole-Dipole Interaction – Hydroxyl – Amino – Halo – Mercapto – Carbonyl – Carboxyl
• Functional groups that can participate in hydrophobic interaction – hydrocarbon
mrsantiago (Chem 200 lab, AY 2014-2015)
ACID AND BASE
• Bronsted Acid and Bases
– Acid: proton donor
– Base: proton acceptor
• Lewis Acid and Bases
– Acid: e- acceptor
– Base: : e- donor
mrsantiago (Chem 200 lab, AY 2014-2015)
Solubility in 5% HCl
mrsantiago (Chem 200 lab, AY 2014-2015)
Solubility in 5% HCl
• Basicity
• Availability of electron pairs
(the more available the electrons, the more readily they can be donated to form a new bond to the proton and, the stronger base)
mrsantiago (Chem 200 lab, AY 2014-2015)
• Electronegativity ( CH3- > NH2
- > HO- > F-) the more e- the atom donating the electrons , the less willing it is to share those electrons with a proton, so the weaker the base.
Solubility in 5% HCl
mrsantiago (Chem 200 lab, AY 2014-2015)
• Size (F- > Cl- > Br- > I- )
the larger the atom the weaker the H-X bond and the lower the electron density making it a weaker base
• Resonance (RO- > RCO2- )
electrons less available when they localised on a specific atom
Solubility in 5% NaOH
• ACIDITY
• Electronegativity (HF > H2O > NH3 > CH4 )
the more electronegative the anionic atom in the conjugate base, the better it is at accepting the negative charge, stronger acid.
• Size (HI > HBr > HCl > HF)
The size weakens the bond H-X, weaker acid
• Resonance (RCO2H > ROH)
mrsantiago (Chem 200 lab, AY 2014-2015)
Acidity trend of common organic acids and bases
mrsantiago (Chem 200 lab, AY 2014-2015)
Sample Physical state Solubility in H20
Solubility in HCl (Basic)
Solubility in NaOH (Acid)
Cyclohexane L (gas-like) - - -
Dichloromethane L (Cl-like) - - -
Ethanol l (wine-like) + + +
Phenol l (pungent - - +
Benzoic acid s (pungent) - - + (wa)
Ethyl acetate l (plastic balloon-like)
+ + +
Ethyl amine l(fish-like) + + -
mrsantiago (Chem 200 lab, AY 2014-2015)
Summary (Expt 6)
FLAMMABILITY/COMBUSTIBILITY OF ORGANIC COMPOUNDS
• Complete Combustion:
CxHy + O2 CO2 + H2O
• Incomplete Combustion:
CxHy + O2 CO2 + CO + C + H2O
• C:H ratio, combustible, luminosity, soot
mrsantiago (Chem 200 lab, AY 2014-2015)
Sample Flammability (C:H)
Hexane 6:14
Heptane 7:16
Cyclohexane 6:12
Cyclohexene 6:10
Benzene 6:6
Toluene 7:8
Solubility in conc. H2SO4
mrsantiago (Chem 200 lab, AY 2014-2015)
Solubility in conc. H2SO4
mrsantiago (Chem 200 lab, AY 2014-2015)
mrsantiago (Chem 200 lab, AY 2014-2015)
TEST FOR ACTIVE UNSATURATION
• Immediate reaction to halogenating substances such the diatomic halogen compounds (Br2, Cl2, I2 and F2)
• Easily oxidized to saturated HC
– Order of oxidation of HC: Alkyne Alkene Alkane
• Tests for Active Unsaturation:
– Br2 Test
– Baeyer’s Test
mrsantiago (Chem 200 lab, AY 2014-2015)
1. BROMINE TEST (AE) Rgt: Br2 in DCM solution
+ Result: decolorization of Br2 in DCM
mrsantiago (Chem 200 lab, AY 2014-2015)
2. BAEYER’S TEST (REDOX) Rgt: Aqueous KMnO4
+ Result: decolorization of KMnO4 and brown ppt.
mrsantiago (Chem 200 lab, AY 2014-2015)
Summary: Test for Active Unsaturation
mrsantiago (Chem 200 lab, AY 2014-2015)
Sample Baeyer’s Br2 in DCM
Hexane - -(slow)
Heptane - -(slow)
Cyclohexane - -(slow)
Cyclohexene +++ (fast) +++ (fast)
Benzene - -
Toluene - (slow) - (slow)
AROMATICITY HYDROCARBONS (HUCKLE’S RULE)
1. Cyclic
2. Planar
3. Conjugated double bonds
4. #e- = 4n + 2, where n I
mrsantiago (Chem 200 lab, AY 2014-2015)
TEST FOR AROMATICITY
• Nitration of the aromatic ring
Preparation of Nitrating Agent:
HNO3 + H2SO4 NO2+ + 2HSO4
- + H3O+ Prevents dilution of NO2
+ by absorbing water in the mixture
Nitration of the Aromatic Ring (SE)
mrsantiago (Chem 200 lab, AY 2014-2015)
Test for arenes: BASIC OXIDATION TEST
• Test for arenes (alkylbenzene)
• Oxidation of alkyl group to COOH
mrsantiago (Chem 200 lab, AY 2014-2015)
Summary (Expt 7)
mrsantiago (Chem 200 lab, AY 2014-2015)
Sample Flammability (C:H)
Solubility in H2SO4
Baeyer’s Br2 in DCM Nitration Basic Oxidation
Hexane 6:14 - - -(slow) -
Heptane 7:16 - - -(slow)
-
Cyclohexane 6:12 - - -(slow)
-
Cyclohexene 6:10 + (alkene/alkyne)
+++ (fast) +++ (fast) - +++ (fast)
Benzene 6:6 - - - +++ (fast)
Toluene 7:8 - - (slow) - (slow) +++ (fast)
- (slow)