Module 4, Section 2 Flashcards
How do you prepare an aldehyde from an alcohol?
Primary Alcohol
Distil with K2Cr2O7/H2SO4
CHO
Dichromate(VI) ions change from orange to green
How do you prepare a carboxylic acid from an alcohol?
Primary alcohol
Reflux with K2Cr2O7/H2SO4
COOH
How do you prepare a ketone from an alcohol?
Secondary Alcohol
Reflux with K2Cr2O7/H2SO4
CO
Describe dehydration of an alcohol
Heated under reflux in presence of acid catalyst eg H2SO4 or H3PO4
Alcohol = Alkene
Describe substitution of alcohols
React with hydrogen halides
Heated under reflux with sulphuric acid
What is the trend in strength of haloalkane bonds?
C-F strongest
C-Cl
C-Br
C-I weakest
What occurs in the free radical substitution involving CFC’s?
Propagation:
1) Cl. + O3 = O2 + ClO.
2) ClO. + O = O2 + Cl.
Overall: O3 + O = 2O2
What happens in the free radical substitution involving nitrogen oxide?
Propagation:
1) NO. + O3 = NO2. + O2
2) NO2. + O = NO. + O2
Overall: O3 + O = 2O2
How does refluxing get around the problem of very reactive organic compounds?
Liebig condenser continuously boils, evaporates and condenses vapours, giving them time to react.
Why shouldn’t naked flames be used in refluxing?
They could ignite very reactive compound
In separation, what are the two different layers present?
Organic layer less dense than aqueous layer, so should float on the top.
How do you get from an alkane to haloalkane?
X2 and UV light
How do you get from an alkene to an alkane?
H2, Nickel catalyst and 150 degrees celsius
How do you get from an alkene to a dihaloalkane?
X2 and 20 degrees celsius
How do you get from an alkene to a haloalkane?
HX and 20 degrees celsius
