Transcript Chromic acid test

Group 1
Alcohols
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Alcohols are compounds containing the
hydroxyl group (-OH)
Presented in general formula ROH
Reactivity is mainly attributed to the -OH
group
Is a weak acid due to the hydrogen ion
released from the -OH bond
Is water soluble due to H-bonding
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Based on alkyl group, alcohol may be
classified into
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-Primary
----n-propyl alcohol
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-Secondary
----sec-butyl alcohol
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-Tertiary
----tert-butyl alcohol
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Alcohols may be classified based on the
number of OH groups as
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-Monohydroxy
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-Polyhydroxy
Chromic acid test
Can detect the presence of/or can
differentiate:
Alcohols, primary and secondary (1o ,2o) Phenols
Test Reagent
K2Cr2O7 in H2SO4
Potassium Dichromate
Visible Results
Blue green precipitate
for positive results
Lucas Test
Can detect the presence of/or can
differentiate:
Alcohols, primary secondary and tertiary
(1o,2o,3o) phenols
Test Reagent
ZnCl2 in HCl
Alkyl halide
OH becomes Cl
Visible Result
Rate: Benzylic
(false positive > tertiary > secondary > primary)
Formation of emulsion
1o,2o soluble no reaction
Aromatic cpds. and 3o
Esterification
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It happens between the reaction of an
alcohol and a carboxylic acid
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Releases fruity odor
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For example
When Salicylic acid reacts with Methanol , Methyl
Salicylate is formed. C6H4(OH)COOCH3 or C8H8O3
CH3 - OH
O
H – C – H + H2
Methyl alcohol:
A colorless, volatile,water-soluble,poisonous liquid.
Obtained by the destructive distillation of wood or
the incomplete oxidation of natural gas, or produce
synthetically from carbon monoxide and hydrogen,
used chiefly as a solvent, a fuel, and an automobile
antifreeze and in the synthesis of formaldehyde.
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POSITIVE RESULT:
- Pink-red ring at the junction due to
the formation of hemiacetal.
Hemiacetal:
- Class of organic chemical compounds
having the general formula RCH(OH)OR,
Where R is an organic group.
TEST COMPOUND
REAGENT
RES.ULT
EXPLANATION
Methyl alcohol
Copper wire
and
H2SO4
[+] Pink-red ring
at
The junction
Formation of a
hemiacetal.
Test for Iodoform
Iodoform Test
Iodoform is the organ iodine
compound with the formula CHI3. A
pale yellow, crystalline, volatile
substance, it has a penetrating odor
(in older chemistry texts, the smell is
sometimes referred to as the smell of
hospitals) and, analogous
to chloroform, sweetish taste. It is
occasionally used as a disinfectant.
Can detect presence of/
Differentiate between:
2o alcohol (methyl alcohol)
Test Reagent:
Iodine bleach (I₂ –NAOH)
Visible Result:
Light yellow precipitate in solution
(can also detect methyl ketones)
Test for Glycerol
Acrolein Test
Acrolein Test
• One of the test for glycerol is the Acrolein Test.
Acrolein test is a test for the presence of
glycerin or fats. A sample with KHSO₄, and
acrolein is released. When a fat is heated
strongly in the presence of a dehydrating
agent such as KHSO₄, the glycerol portion of
the molecule is dehydrated to form the
unsaturated aldehyde, acrolein(CH₂=CH-CHO),
which has the peculiar odor of burnt grease.
Can detect the presence of:
Glycerol
Test Reagent:
Potassium bisulfate
Visible result:
Pungent odor
Fermentation
The overall process of fermentation is to convert glucose
sugar (C6H12O6) to alcohol (CH3CH2OH) and carbon
dioxide gas (CO2). The reactions within the yeast cell which
make this happen are very complex but the overall process
is as follows:
C6H12O6 ====> 2(CH3CH2OH)
stored in ATP)
Sugar
====>
Alcohol
(Glucose)
(Ethyl alcohol)
+
2(CO2)
+ Energy (which is
+ Carbon dioxide gas + Energy
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Since we didn't perform the experiment I will
explain the procedures.
The pineapple- To obtain Glucose
Yeast- important in fermentation, which
serves as an enzyme
Lime water – to test the presence of Carbon
Dioxide
The flammability test and Chromic acid test.