I read about Ceric Ammonium Nitrate Test for Alcohols and a red colour is produced if the solution has an alcohol functional group however as a side note it was mentioned that this test is only useful for compounds having less than 10 Carbon atoms. Why is it so?
The question does not mention in what the ammonium cerium nitrate is dissolved in, but I guess it is water. If so, one expects that sufficiently large compounds that one wishes to test are not sufficiently soluble in water, such as decanol. Obviously, this is not entirely correct because disaccharides such as lactose do are soluble in water.
I expect a sufficient solubility to be important for the test such that it finishes in a timely manner and does not become inconclusive due to prolonged reactions with air, water etc.