Aromatic aldehydes do not respond to Fehling’s test. Be the first to answer! An aqueous solution of the compound may be used instead of an alcoholic solution. The test gives no red precipitate Cu 2 O as it appears only for aliphatic aldehydes, hence this test is used to differentiate aliphatic and aromatic hydrocarbon. Aromatic aldehydes do not respond to Fehling’s test. Whereas fehlings is reduced by only aliphatic aldehyde. There are lots of other things which could also give positive results. Note: Follow this link to find out how to test for the carbon-oxygen double bond in aldehydes and ketones. First of all we know that group i.e. General equation for: RCHO + CuSO4 → R-COOH + Cu 2 O + H 2 O Note: The appearance of red precipitate confirms the presence of an aldehydic group. Tollens test is given by aldehydes including both aromatic and aliphatic aldehydes. aldehyde gives positive test with Fehling’s solution whereas ketones don't give positive test with it. 2. Formic acid also gives this test. Why does the Chromic acid test only work for aldehydes? The test are coducted in 4ml test tube generallly by adding benedicts reagent with small drops of unknown substance for us the given compound benzaldehyde and heated in water bath for 95 centigrade. But aromatic aldehydes do not form cuprous oxide (red precipitate) as they are not good reducing agents. Examples are given in detail below. Formic acid also give this test. Tests to differentiate between aldehydes and ketones - definition 1. Specific examples. Tollen's Test: Aldehydes gives positive Tollen's test to give silver mirror while ketones do not give any reaction. Asked by Wiki User. Note: Appearance of red precipitate confirms the presence of an aldehydic group. 1. In each of the following examples, we are assuming that you know that you have either an aldehyde or a ketone. 2. Why Benedict's test doesn't react with aromatic aldehydes? Aromatic aldehydes do not show this reaction. Page 1 of 3 Benedict’s Test Procedure Preparation of Benedict’s Reagent. Answer . 3. Who doesn't love being #1? Be the first to answer this question. One litre of Benedict’s reagent can be prepared by mixing 17.3 grams of copper sulfate pentahydrate (CuSO 4.5H 2 O), 100 grams of sodium carbonate (Na 2 CO 3), and 173 grams of sodium citrate in distilled water (required Okay I will explain this here. (e) Tollen’s Test: (Silver Mirror Test) This test is also called the silver mirror test. Why do aromatic aldehydes do not give a positive test with Benedict's reagent? 0 1 2. An aqueous solution of the compound may be used instead of an alcoholic solution. Fehling's test: Aliphatic aldehydes on treatment with Fehling's solution gives a reddish brown precipitate while aromatic aldehydes and ketones do not.