Advertisements
Advertisements
प्रश्न
An organic compound contains 69.77% carbon, 11.63% hydrogen and rest oxygen. The molecular mass of the compound is 86. It does not reduce Tollens’ reagent but forms an addition compound with sodium hydrogensulphite and give positive iodoform test. On vigorous oxidation it gives ethanoic and propanoic acid. Write the possible structure of the compound.
Advertisements
उत्तर
(a) Finding the molecular formula of a compound:
Percentage of carbon = 69.77%
Percentage of hydrogen = 11.63%
∴ Percentage of oxygen = 100 – (69.77 + 11.63)
= 18.6%
C : H : O = `69.77/12 : 11.63/1 : 18.6/16`
= 5.81 : 11.63 : 1.16
∴ Simple ratio = 5 : 10 : 1
Empirical formula of the given compound = C5H10O
Empirical formula mass = 5 × 12 + 10 × 1 + 1 × 16 = 86
Molecular mass = 86 ...(Given)
Molecular formula = C5H10O × `86/86` = C5H10O
Thus, the molecular formula of the given compound is C5H10O.
(b) Determining the structure of a compound:
- Since the given compound forms a divalent compound with sodium hydrogensulphite, it must be an aldehyde or a ketone.
- Since the compound does not reduce Tollen's reagent, it cannot be an aldehyde. Hence, it must be a ketone.
- Since the compound gives an iodoform test, the given compound is methyl ketone.
- Since the given compound gives a mixture of ethanoic acid and propanoic acid on vigorous oxidation, methyl ketone is pentane-2-one. Its structure is as follows:
\[\begin{array}{cc}
\ce{O}\phantom{........}\\
||\phantom{........}\\
\ce{\underset{Pentan-2-one}{CH3 - C - CH2CH2CH3}}
\end{array}\]
(c) Details of the reactions involved:
\[\begin{array}{cc}
\phantom{.................}\ce{O}\phantom{...........................}\ce{OH}\phantom{.....}\ce{S\overset{-}{O}_3N\overset{+}{a}}\\
\phantom{..........}||\phantom{...............................}\backslash\phantom{...}/\\
\ce{CH3 - \underset{Pentan-2-one}{C - CH2}CH2CH3 + NaHSO3 -> C}\\
\phantom{..........................................}/\phantom{...}\backslash\\
\phantom{..................................}\ce{\underset{Sodium Hydrogen Sulphite Additive Products}{CH3CH2H2C \phantom{.....}CH3}}
\end{array}\]
\[\begin{array}{cc}
\ce{O}\phantom{....................................................................................}\\
||\phantom{....................................................................................}\\
\ce{CH3 - \underset{Pentan-2-one}{C - CH2}CH2CH3 + 3I2 + 4NaOH ->[Iodoform][reaction]\underset{(Yellow ppt)}{\underset{Iodoform}{CH3\downarrow}} + CH3CH2CH2COONa + 3NaI + 3H2O}
\end{array}\]
\[\begin{array}{cc}
\ce{O}\phantom{...............................................}\\
||\phantom{...............................................}\\
\ce{CH3 - \underset{Pentan-2-one}{C - CH2}CH2CH3->[K2Cr2O7][H2SO4] \underset{Ethanoic acid}{CH3COOH} + \underset{Propanoic acid}{CH3CH2COOH}}
\end{array}\]
APPEARS IN
संबंधित प्रश्न
A and B are two functional isomers of compound C3H6O.On heating with NaOH and I2, isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the formulae of A and B.
Predict the products of the following reactions :
Give a simple chemical test to distinguish between the following pair of compounds :
CH3CH2CHO and CH3CH2COCH3
Propanal and Propanone
How will you convert ethanal into the following compound?
But-2-enoic acid
Give a simple chemical test to distinguish between the following pair of compounds:
Benzaldehyde and Acetophenone
Complete the synthesis by giving missing starting material, reagent or product.
Alkenes decolourise bromine water in presence of CCl4 due to formation of ______.
Which of the following compounds will give butanone on oxidation with alkaline \[\ce{KMnO4}\] solution?
Which sugar does not reduce Fehling's solution?
Fehilng's test is positive for
Which of the following tests/reactions is given by aldehydes as well as ketones?
A hydrocarbon (A) with molecular formula C5H10 on ozonolysis gives two products (B) and (C). Both (B) and (C) give a yellow precipitate when heated with iodine in presence of NaOH while only (B) give a silver mirror on reaction with Tollen’s reagent.
- Identify (A), (B) and (C).
- Write the reaction of B with Tollen’s reagent.
- Write the equation for iodoform test for C.
- Write down the equation for aldol condensation reaction of B and C.
The major products formed in the following reaction sequence A and B are:
An organic compound neither reacts with neutral ferric chloride solution nor with Fehling solution. It however, reacts with Grignard reagent and gives positive iodoform test. The compound is:
You are given four organic compounds “A”, “B” , “C” and “D”. The compounds “A”, “B” and “C” form an orange-red precipitate with 2, 4 DNP reagent. Compounds “A” and “B” reduce Tollen’s reagent while compounds “C” and “D” do not. Both “B” and “C” give a yellow precipitate when heated with iodine in the presence of NaOH. Compound “D” gives brisk effervescence with sodium bicarbonate solution. Identify “A”, “B”, “C” and “D” given the number of carbon atoms in three of these carbon compounds is three while one has two carbon atoms. Give an explanation for our answer.
Fehling’s solution ‘A’ is ______.
