Classification test of organic compounds
mrsantiago (Chem 200 lab, AY 2014-2015)
Physical and chemical properties Physical Physical properties •
Physical 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)
Solubility in water
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
FUNCTIONAL GROUPS THAT MAY CAUSE IMFA •
Functional groups that can participate in H-bonding – – – –
•
Functional groups that can participate Dipole-Dipole Interaction – – – – – –
•
Carboxyl Carbonyl Hydroxyl Amino 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 )
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 •
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
mrsantiago (Chem 200 lab, AY 2014-2015)
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)
Summary (Expt 6) 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)
FLAMMABILITY/COMBUSTIBILITY OF ORGANIC COMPOUNDS Complete Combustion:
Sample
Flammability (C:H)
CxHy + O2 CO2 + H2O Incomplete Combustion: CxHy + O2 CO2 + CO + C + H 2O
Hexane
6:14
Heptane
7:16
Cyclohexane
6:12
Cyclohexene
6:10
Benzene
6:6
Toluene
7:8
•
•
•
C:H ratio, combustible, luminosity, soot
Solubility in conc. H2SO4
Solubility in conc. H2SO4
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
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 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 )
Test for arenes: BASIC OXIDATION TEST •
Test for arenes (alkylbenzene)
•
Oxidation of alkyl group to COOH
Summary (Expt 7) Sample
Flamma bility (C:H)
Solubility in H2SO4
Baeyer’s
Br2 in DCM Nitration
Hexane
6:14
-
-
-(slow)
-
Heptane
7:16
-
-
-(slow)
-
Cyclohexane
6:12
-
-
-(slow)
-
Cyclohexene
6:10
+ (alkene/alk yne)
+++ (fast)
+++ (fast)
-
Benzene
6:6
-
-
-
+++ (fast)
Toluene
7:8
-
- (slow)
- (slow)
+++ (fast)
Basic Oxidation
+++ (fast)
- (slow)
