0
Because it's a test for phenols or enols. Please see the link.
Wiki User
∙ 10y ago
Add your answer:
Earn +20 pts
What is the chemical equation between phenol and ferric chloride?
We use Ferric Chloride (FeCl3) in the lab to test for the presence (or in some case absence) of phenols, although some enols will also yield positive results. The OH (hydroxy group) which is attached directly to an aromatic nucleus (Benzene, for example) is detected by the Ferric chloride. It is important to note that alcohols do not undergo the reaction. Phenols will typically yield dramatic purple,blue,red or green color as an indication of a positive test. FeCl3 will also indicate the presence of aliphatic acids (that is, non-aromatic organic acids, such as Acetic acid) turning the solution a yellow color. Aromatic acids will test as a beige-tan color. Enols will also show a characteristic yellow color. It is also important to understand that not all phenols will test positively in the presence of the FeCl3 reagent. A good example of this is in highly hindered phenols which do not yield positive tests. However, a negative test is not completely conclusive, so other tests can be preformed to verify the absence of a phenol (such as NMR and IR spectroscopy) We use Ferric Chloride (FeCl3) in the lab to test for the presence (or in some case absence) of phenols, although some enols will also yield positive results. The OH (hydroxy group) which is attached directly to an aromatic nucleus (Benzene, for example) is detected by the Ferric chloride. It is important to note that alcohols do not undergo the reaction. Phenols will typically yield dramatic purple,blue,red or green color as an indication of a positive test. FeCl3 will also indicate the presence of aliphatic acids (that is, non-aromatic organic acids, such as Acetic acid) turning the solution a yellow color. Aromatic acids will test as a beige-tan color. Enols will also show a characteristic yellow color. It is also important to understand that not all phenols will test positively in the presence of the FeCl3 reagent. A good example of this is in highly hindered phenols which do not yield positive tests. However, a negative test is not completely conclusive, so other tests can be preformed to verify the absence of a phenol (such as NMR and IR spectroscopy)
Why is it that millon's test cannot be used to detect the presence of protein in the urine?
This test is never used for detection of tyrosine in urine, because urine contain chloride that chloride ions interfere with this test by combining with mercury chloride (HgCl2)
What is Lucas reagent?
This is a mixture of concentrated hydrochloric acid and anhydrous zinc chloride (which acts as a catalyst). To prepare, mix 136.29 g of anhydrous zinc chloride (ZnCl2) with 105 g of concentrated hydrochloric acid (HCl). Place beaker in an ice bath, due to the exothermic reaction. Stir with a glass rod until all ZnCl2 is dissolved.
Given a pure sample that is either pure benzoic acid or 2-naphthol give a procedure that can be used to determine the identity of the sample?
Lets see. Add neutral ferric chloride to the sample solution. A coloured solution is obtained if it is 2-naphthol (most phenols give colour with neutral ferric chloride solution). Add sodium bicarbonate to the sample solution. Carboxylic acids evolve carbon dioxide gas. Phenols (except strong ones like picric acid) does not. Both 2-naphthol and benzoic acid will evolve hydrogen when treated with metallic sodium (test not advisable to do) and NaOH. Phenols form pleasent smelling esters when treated with carboxylic acids where as benzoic acid will be fruity odour with alcohols or phenols. Both benzoic acid and 2-naphthol melts about 1220C whereas the boiling point of benzoic acid is 2490C and that of 2-naphthol is 2850C.
How do you test insoluble matter in soap?
through the copper sulphate test, magnesium sulphate and calcium chloride test.
Why acetoacetic ester gives ferric chloride test?
acetoacetic aster gives ferric chloride test which is a typical test for phenols?
Why is ferric chloride used in modified borntrager's test?
ferric chloride causes the oxidative hydrolysis.
Is vanillin positive in a ferric chloride test?
yes
What is the mechanism of ferric chloride test?
reaction and meachanism of neutral feric chloride with phenols
Why would vanillin test positive in a ferric chloride test?
It would test positive because there is a phenol group in vanillin.
Why using phosphate buffer and magnesium sulphate and calcium chloride and ferric chloride for dilution water in BOD5 test?
magnesium sulphate, calcium chloride and ferric chloride are added to provided optimum environment and phosphate buffer is added to slow down the rate of death of microbes.
2 Why does aspirin not give a positive ferric chloride test as salicylic acid does?
Because aspirin does not contain OH group like salicyclic acid so ferric chloride preferes to react with a compounds that have OH group.
What is Hehner's test?
Hehner's test is used to detect the formaldehyde in milk by adding sulfuric acid containing the traces of ferric chloride.
What is basic ferric acetate test?
It is a test when we put ferric chloride in a slightly alkaline solution check for the presence of acetate (CH3COO) 3CH3COOH + FeCl3 + 3NaOH ----------> Fe(CH3COOH)3 + 3NaCl + 3 H2O
Lucas reagent is used to test what homologous series?
Lucas reagent is used to test for the presence of alcohols in a substance. It is made from anhydrous zinc chloride and concentrated hydrochloric acid.
What does bial's orcinol test determine in samples?
The positive result- the resulting blue solution, indicates that the test carbohydrates is a pentose(ribose for example). The blue color is due to the iron content of ferric chloride.
How do you prepare neural ferric chloride solution?
The ferric chloride test is used to determine the presence or absence of phenols in a given sample. Enols give positive results as well. The bromine test is useful to confirm the result, although modern spectroscopic techniques (e.g. NMR and IR spectroscopy) are far superior in determining the identity of the unknown. The quantity of total phenols may be spectroscopically determined by the Folin-Ciocalteau assay.
