Victor Meyer test- used to distinguish between 1,2 & 3 degree alcohols.
Also knows as Red-Blue test.
1o - Red
2o- Blue
3o- No colour
Well, its difficult to show the reactions of all the three types of alcohols here, but I am telling you the reactions in words. U will understand.
First react with P + I2, you will get an alkyl halide.
R-CH2-OH-->R-CH2-I , R2-CH-OH--->R2-CH-I, R3-C-OH-->R3-C-I
Then, react with AgNO2 and replace I in above compounds with NO2.
R-CH2-I-->R-CH2-NO2 , R2-CH-I--->R2-CH-NO2, R3-C-I-->R3-C-NO2
Finally react with HNO2, elimination of water takes place and as there is no alpha H in 3o alcohol, this alcohol doesnt react in this reaction.
R-CH2-NO2 --> R-C(NO2)=N-OH , R2-CH-NO2 ---> R2-C(NO)-NO2
R-C(NO2)=N-OH - Nitrolic Acid(Red)
R2-C(NO)-NO2 - Pseudonitrole(Blue)
Moderation Team
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