A compound is soluble in water. It shows negative for the 2, 4-DNPH test and neg

Question

A compound is soluble in water. It shows negative for the 2, 4-DNPH test and negative for Chromic Acid test. What do you think the compound is? a) 2-methylpropan-2-ol b) Butyraldehyde c) 3-pentanone d) butan-l-ol Which compound would give a positive result for Iodoform Test? a) Methanol b) 4-Methylcyclohexanol c) Acetaldehyde d) Acetyl methyl carbinol Which of the following routes can be used to differentiate between phenol and carboxylic acid? a. Test solubility in NaOH b. Test solubility in NaHCO_3 c. Iodoform test d. Hisenberg test What is the product of water and pentyl ethanoate under acidic conditions? a. Ethanoic acid and pentanol b. Butanol and water c. Ethanoic acid, two equivalents d. Pentanol, two equivalents The results for a student that just performed sodium fusion were a Prussian blue solution in one beaker and a red brown precipitate in the second beaker? a. P-Bromoaniline b. M-bromophenol c. 1-Chloro-2-nitronaphthalene d. Hexane Which of the following tests could not be used to distinguish between the following compounds? a. Bromine in CH_2 CI_2 Test b. Lucas Test c. Iodoform test d. Potassium permanganate test

Explanation / Answer

1) DNPH test is to identify aldehydes and ketones. While chromic acid test is for the identification of primary and secondary alcohols and aldehydes. Here the unknown, shows negative for both tests eliminating options: b, c,d. Hence the compound must be a tertiary alcohol.

Ans (a)

2) Iodoform test is used to identify the presence of CH3CO group in compunds of the type: CH3COR where R = H, alkyl gp. From the given options only acetaldehyde CH3CHO will give a positive result.

Ans (c)

3) In the presence of NaHCO3, carboxylic acids will release CO2, unlike phenols.

Ans (b)

4) Ans (a)

H2O + CH3COOCH2CH2CH2CH2CH3 ----- CH3COOH + HOCH2CH2CH2CH2CH3

water + pentyl ethanoate ------------------------- Ethanoic acid + Pentanol

5) In the sodium fusion test, a prussian blue precipitate indicates the presence of Nitrogen while a reddish brown precipitate indicates Bromine. Hence the compound is p-bromoaniline (p-C6H4NH2Br)

Ans (a)

6) Br2 in CH2Cl2 is a test for the presence of unsaturation of phenols. Since both compounds are unsaturated both with give a positive test and hence will be indistinguisable. The other tests, distinguish primary alcohols from tertiary alcohols.

Ans (a)

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