Write steps to carry out the conversion
Question: Write steps to carry out the conversion of phenol to aspirin. Solution: Phenol is treated with NaOH to produce phenoxide ion. Phenoxide ion then undergoes electrophilic substitution with CO2 to yield salicylic acid as the major product. This is called Kolbes reaction....
Read More →Why is the reactivity of all the three classes
Question: Why is the reactivity of all the three classes of alcohols with conc? HCl and ZnCl2 (Lucas reagent) different? Solution: This is because of the steric hindrance of the alkyl group and the stability of carbocation. Primary alcohol does not show any reaction at room temperature because the 1 carbocation is least stable. Secondary alcohol does not show any turbidly at room temperature but on heating, turbidity appears. Tertiary alcohol immediately shows turbidity after addition of Lucas r...
Read More →Explain why is O=C=O nonpolar
Question: Explain why is O=C=O nonpolar while ROR is polar. Solution: O=C=O nonpolar because the dipole moment of the two C=O bonds is exactly equal and opposite of each other. Therefore, they cancel each other and so, the net dipole moment of O=C=O is zero....
Read More →Explain why nucleophilic substitution
Question: Explain why nucleophilic substitution reactions are not very common in phenols. Solution: Due to the resonance, the ortho- and para-positions in the benzene ring becomes electron-rich and therefore, activates it towards electrophilic substitution reaction. Thus, nucleophilic substitution reactions are not very common in phenols...
Read More →Mark (√) against the correct answer in the following:
Question: Mark () against the correct answer in the following: If $f(x)=\left(x^{2}-1\right)$ and $g(x)=(2 x+3)$ then $(g \circ f)(x)=?$ A. $\left(2 x^{2}+3\right)$ B. $\left(3 x^{2}+2\right)$ C. $\left(2 x^{2}+1\right)$ D. None of these Solution: $f(x)=\left(x^{2}-1\right)$ $g(x)=(2 x+3)$ $\therefore(g \circ f)(x)=g(f(x))$ $\Rightarrow \mathrm{g}(\mathrm{f}(\mathrm{x}))=2 \mathrm{f}(\mathrm{x})+3$ $\Rightarrow g(f(x))=2\left(\left(x^{2}-1\right)\right)+3=2 x^{2}-2+3=2 x^{2}+1$...
Read More →Explain why the OH group in phenols is
Question: Explain why the OH group in phenols is more strongly held as compared to OH group in alcohols. Solution: The OH group in phenol is directly attached to the sp2hybridized carbon atom of the benzene ring. The carbon-oxygen bond length in phenol is smaller as compared to the carbon-oxygen bond length in alkyl alcohol and this is due to the partial double bond character or due to the resonance and charge distribution in phenol....
Read More →Mark (√) against the correct answer in the following:
Question: Mark () against the correct answer in the following: If $f(x)=\frac{(4 x+3)}{(6 x-4)}, x \neq \frac{2}{3}$ then $(f$ of $f(x)=?$ A. $\mathrm{X}$ B. $(2 x-3)$ C. $\frac{4 x-6}{3 x+4}$ D. None of these Solution: $f(x)=\frac{4 x+3}{6 x-4}$ $\Rightarrow \mathrm{f}(\mathrm{f}(\mathrm{x}))=\frac{4 \mathrm{f}(\mathrm{x})+3}{6 \mathrm{f}(\mathrm{x})-4}=(\mathrm{f}$ of $\mathrm{f})(\mathrm{x})$ $\Rightarrow \mathrm{f}(\mathrm{f}(\mathrm{x}))=\frac{4\left(\frac{4 \mathrm{x}+3}{6 \mathrm{x}-4}\ri...
Read More →How can propane-2-one be converted
Question: How can propane-2-one be converted into tert- butyl alcohol? Solution: Propane-2-one is treated with CH3MgBr in the presence of dry ether (Grignard reagent), followed by the hydrolysis to yield tert- butyl alcohol....
Read More →Arrange the following compounds in decreasing
Question: Arrange the following compounds in decreasing order of acidity. H2O, ROH, HC CH Solution: The decreasing order of the acidity of the given compounds: H2O ROH HC CH HC CH is less acidic because the carbon atoms here is sp hybridized, so the electron density is higher on the carbon atom....
Read More →What happens when benzene diazonium
Question: What happens when benzene diazonium chloride is heated with water? Solution: When benzene diazonium chloride is heated with water, Phenol is formed along with the by-products, Nitrogen gas and Hydrochloric acid....
Read More →Alcohols react with active metals e.g. Na,
Question: Alcohols react with active metals e.g. Na, K etc. to give corresponding alkoxides. Write down the decreasing order of reactivity of sodium metal towards primary, secondary and tertiary alcohols Solution: The decreasing order of reactivity of sodium metal towards alcohols: Primary alcohols secondary alcohols tertiary alcohols The reactivity of sodium metal towards tertiary alcohols is lowest mainly due to two reasons. First, steric hindrance of the alkyl groups. Second, an increase in t...
Read More →Evaluate the following integrals -
Question: Evaluate the following integrals - $\int(x+1) \sqrt{x^{2}+x+1} d x$ Solution: Let $I=\int(x+1) \sqrt{x^{2}+x+1} d x$ Let us assume $x+1=\lambda \frac{d}{d x}\left(x^{2}+x+1\right)+\mu$ $\Rightarrow x+1=\lambda\left[\frac{d}{d x}\left(x^{2}\right)+\frac{d}{d x}(x)+\frac{d}{d x}(1)\right]+\mu$ We know $\frac{\mathrm{d}}{\mathrm{dx}}\left(\mathrm{x}^{\mathrm{n}}\right)=\mathrm{n} \mathrm{x}^{\mathrm{n}-1}$ and derivative of a constant is 0 . $\Rightarrow x+1=\lambda\left(2 x^{2-1}+1+0\rig...
Read More →Arrange the following compounds in increasing
Question: Arrange the following compounds in increasing order of acidity and give a suitable explanation. Phenol, o-nitrophenol, o-cresol Solution: Increasing order of the acidity of the given compounds: o-cresol Phenol o-nitrophenol. Due to the presence of the electron-withdrawing group, NO2 o-nitrophenol becomes more acidic. Remaining has an electron releasing group which decreases the acidic strength....
Read More →Mark (√) against the correct answer in the following:
Question: Mark () against the correct answer in the following: Let $f: N \rightarrow X: f(x)=4 x^{2}+12 x+15 .$ Then, $f^{-1}(y)=?$ A. $\frac{1}{2}(\sqrt{\mathrm{y}-4}+3)$ B. $\frac{1}{2}(\sqrt{\mathrm{y}-6}-3)$ C. $\frac{1}{2}(\sqrt{\mathrm{y}-4}+5)$ D. None of these Solution: $f(x)=4 x^{2}+12 x+15$ $\Rightarrow y=4 x^{2}+12 x+15$ $\Rightarrow y=(2 x+3)^{2}+6$ $\Rightarrow \sqrt{(} y-6)=2 x+3$ $\Rightarrow \frac{1}{2}(\sqrt{y-6}-3)=x$ $f^{-1}(y)=\frac{1}{2}(\sqrt{y-6}-3)$...
Read More →Out of o-nitrophenol and o-cresol
Question: Out of o-nitrophenol and o-cresol which is more acidic? Solution: There is an electron-withdrawing group NO2 that is present in the ortho position in ortho-nitrophenol which enhances the acidic strength and makes more acidic. In o- cresol there is an electron releasing group, they decrease acidic strength....
Read More →Out of o-nitrophenol and p-nitrophenol,
Question: Out of o-nitrophenol and p-nitrophenol, which is more volatile? Explain. Solution: Due to the presence of intramolecular hydrogen bonding between NO2 and OH group the o-nitrophenol is more volatile....
Read More →Mark (√) against the correct answer in the following:
Question: Mark () against the correct answer in the following: Let $\mathrm{f}: \mathrm{R}-\left\{\frac{-4}{3}\right\} \rightarrow-\left\{\frac{4}{3}\right\}: \mathrm{f}(\mathrm{x})=\frac{4 \mathrm{x}}{(3 \mathrm{x}+4)}$. Then $\mathrm{f}^{-1}(\mathrm{y})=$ ? A. $\frac{4 y}{(4-3 y)}$ B. $\frac{4 y}{(4 y+3)}$ C. $\frac{4 y}{(3 y-4)}$ D. None of these Solution: $f(x)=\frac{4 x}{3 x+4}$ $\Rightarrow y=\frac{4 x}{3 x+4}$ $x \Longleftrightarrow y$ $\Rightarrow \mathrm{x}=\frac{4 y}{3 y+4}$ $\Rightarr...
Read More →Suggest a reagent for conversion
Question: Suggest a reagent for conversion of ethanol to ethanoic acid. Solution: Acidified KMnO4 can be used as a reagent for the above conversion. The above conversion shows the oxidation of primary alcohol to a carboxylic acid....
Read More →Suggest a reagent for conversion
Question: Suggest a reagent for conversion of ethanol to ethanal. Solution: PCC or Pyridinium chlorochromate can be used as reagents. The above conversion shows the oxidation of primary alcohol to an aldehyde....
Read More →Mark (√) against the correct answer in the following:
Question: Mark () against the correct answer in the following: Let $f: Q \rightarrow Q: f(x)=(2 x+3) .$ Then, $f^{-1}(y)=?$ A. $(2 y-3)$ B. $\frac{1}{(2 \mathrm{y}-3)}$ C. $\frac{1}{2}(\mathrm{y}-3)$ D. none of these Solution: $f(x)=2 x+3$ $\Rightarrow y=2 x+3$ $x \Longleftrightarrow y$ $\Rightarrow x=2 y+3$ $\Rightarrow x-3=2 y$ $\Rightarrow \frac{x-3}{2}=y$ $x \Longleftrightarrow y$ $\Rightarrow \frac{y-3}{2}=x$...
Read More →Out of 2-chloroethanol and ethanol
Question: Out of 2-chloroethanol and ethanol which is more acidic and why? Solution: 2-chloroethanol is more acidic because of the presence of chlorine which is an electron-withdrawing group. This results in a negative inductive effect and thus, the electron density in the O-H bond decreases. It stabilizes the alkoxide ion and therefore, 2-chloroethanol can easily release a proton....
Read More →Suggest a reagent for the following conversion.
Question: Suggest a reagent for the following conversion. Solution: The chemical reaction above shows the oxidation of secondary alcohol into a ketone. This can be easily achieved by using oxidizing agents like chromic anhydride (CrO3), Pyridinium chlorochromate (PCC), etc....
Read More →What is denatured alcohol?
Question: What is denatured alcohol? Solution: Alcohols that are used for drinking are made unfit for human consumption by mixing alcohol with some copper sulfate and pyridine, which gives the colour and a foul smell to the liquid respectively. This is called denatured alcohol....
Read More →Name the factors responsible
Question: Name the factors responsible for the solubility of alcohols in water. Solution: The factors responsible for the solubility of alcohols in water are: (I) Hydrogen bonds (II) Size of the alkyl or aryl groups (III) The molecular mass of the Alcohols....
Read More →Write the IUPAC name of the compound given below.
Question: Write the IUPAC name of the compound given below. Solution: IUPAC name of the compound is 3-Methylpent-2-ene-1,2-diol....
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