What are some important distinguishing tests in organic chemistry class 12?

distinguish between 1u00b0 2u00b0 3u00b0 alcohol by lucas test

From what Ive come across so far, there are only a few distinguishing tests which are sometimes asked in the class XII boards.

They are:,1.

Baeyers test: Aqueous bromine when added to unsaturated organic compound, gets decolourised.

DOES NOT work for aromatic hydrocarbons.


Lucass test: Used to distinguish 1u00b0, 2u00b0 and 3u00b0 alcohols.

(Compound is treated with text{HCl} in presence of text{ZnCl}_2.

),Immediate turbidity for 3u00b0 alcohols.

,Turbidity after some time for 2u00b0 alcohols.

,No turbidity for 1u00b0 alcohols.


2,4- DNP test: When 2,4-DNP is added to a compound containing carbonyl group, a red/orange/yellow compound is formed.


Tollens test: Refer to page number 369, chemistry part II.


Fehlings test: Same as above.

DOES NOT work for aromatic aldehydes.


Iodoform test: Refer to page number 370, chemistry part II.

Read it thoroughly.


Sodium bicarbonate test: When text{NaHCO}_3 is added to an acid, brisk effervescence occurs.


Ferric chloride test: When neutral text{FeCl}_3 is added to phenols, violet colour is observed.


Carbylamine test: Refer to page number 401, chemistry part II.


Hinsbergs test: Same as above.

,There are some other tests on the same page as well.

Read them too.


Azodye test: Aromatic primary amines on reaction with text{NaNO}_2 and text{HCl} followed by treatment with u00df-napthol, give yellow/orange/red coloured dye.

On the other hand, aliphatic amines give brisk evolution of text{N}_2.


Libermann nitrosoamine test: Used to distinguish 2u00b0 and 3u00b0 aliphatic amines.

2u00b0 amines give yellow colour on treatment with text{HNO}_2, while 3u00b0 alcohols dont.


Victor-Meyer test: Used to distinguish 1u00b0, 2u00b0 and 3u00b0 alcohols.

An alcohol is treated with Victor-Meyer reagent.

,1u00b0 alcohols: Red colour,2u00b0 alcohols: Blue colour,3u00b0 alcohols: No colour :(,15.

Oxidation test: Used to distinguish 1u00b0, 2u00b0 and 3u00b0 alcohols.

In this test, an alcohol is oxidised with sodium dichromate.

The rate of oxidation varies between the three degrees of alcohol:,1u00b0 Alcohols get easily oxidised to an aldehyde and can be further oxidised to carboxylic acids.

,2u00b0 Alcohols get easily oxidised to ketone but any further oxidation isnt possible.

,3u00b0 Alcohols dont get oxidised in presence of sodium dichromate.

,,Heartfelt thanks to:,Prince Raj for the addition of tests #14 and #15.


for the updation of page numbers.

,Since the answer is around two years old at this point, a few figures like page numbers might have become invalid.

If that is the case, feel free to suggest edits.

Also, if you happen to know tests which are not mentioned in this answer, feel free to suggest an edit as well!,Have a great day!

Primary, secondary tertiary alcohol Structure

In a primary alcohol, the carbon atom bearing the OH group is attached to one other carbon atom or alkyl group (R), in a secondary alcohol it is attached to two alkyl groups (R and Ru2019) and in a tertiary alcohol to three alkyl groups (R, Ru2019, Ru2019u2019).

In each case, R, Ru2019 and Ru2019u2019 may be the same or different.