Question 12 Marks
Write common name and IUPAC name of following alcohol compound.
Answer
View full question & answer→Common name - Glycerol
IUPAC name - Propane -1,2, 3-triol
IUPAC name - Propane -1,2, 3-triol
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Question 22 Marks
Write common name and IUPAC name of following alcohol compound.
Answer
View full question & answer→Common name - tert-Butyl alcohol
IUPAC name - 2-Methyl propan-2-ol
IUPAC name - 2-Methyl propan-2-ol
Question 32 Marks
Write common name and IUPAC name of following alcohol compound.
Answer
View full question & answer→Common name - Isobutyl alcohol
IUPAC name - 2-Methyl propan-1-ol
IUPAC name - 2-Methyl propan-1-ol
Question 42 Marks
Write common name and IUPAC name of following alcohol compound.
Answer
View full question & answer→Common name - sec-Butyl alcohol
IUPAC name - Butan-2-ol
IUPAC name - Butan-2-ol
Question 52 Marks
Write common name and $IUPAC$ name of following alcohol compound.
$CH_3-CH_2-CH_2-CH_2-OH$
$CH_3-CH_2-CH_2-CH_2-OH$
Answer
View full question & answer→Common name $- n-$Butyl alcohol
$IUPAC$ name $-$ Butan$-1-$ol
$IUPAC$ name $-$ Butan$-1-$ol
Question 62 Marks
Write common name and IUPAC name of following alcohol compound.
Answer
View full question & answer→Common name - Isopropyl alcohol
IUPAC name - Propan-2-ol
IUPAC name - Propan-2-ol
Question 72 Marks
Write common name and $IUPAC$ name of following alcohol compound.
$CH_3-CH_2-CH_2-OH$
$CH_3-CH_2-CH_2-OH$
Answer
View full question & answer→Common name $- n-$ Propyl alcohol
$IUPAC$ name $-$ Propan$-1-$ol
$IUPAC$ name $-$ Propan$-1-$ol
Question 82 Marks
Write common name and $IUPAC$ name of following alcohol compound. $CH_3-OH$
Answer
View full question & answer→Common name $-$ Methyl alcohol
$IUPAC$ name $-$ Methanol
$IUPAC$ name $-$ Methanol
Question 92 Marks
Explain the following with an example
(i) Reaction of phenol with zine dust.
(ii) Oxidation reaction of phenol.
(i) Reaction of phenol with zine dust.
(ii) Oxidation reaction of phenol.
Answer
View full question & answer→→ Reaction of phenol with zinc dust: Phenol is converted to benzene on heating with zinc dust.
→ Oxidation Oxidation of phenol with chromic acid produces a conjugated diketone known as benzoquinone. In the presence of air, phenols are slowly oxidised to dark coloured mixtures containing quinones.
→ Oxidation Oxidation of phenol with chromic acid produces a conjugated diketone known as benzoquinone. In the presence of air, phenols are slowly oxidised to dark coloured mixtures containing quinones.
Question 102 Marks
What happens when the vapours of a primary, secondary and tertiary alcohol are passed over heated copper at 573 K temperature? Explain with chemical equation.
Answer
View full question & answer→→ When the vapours of a primary, secondary and tertiary alcohol are passed over heated copper at 573 K, dehydrogenation takes place and an aldehyde or a ketone is formed while tertiary alcohols undergo dehydration.
Question 112 Marks
Write a note on the reaction of alcohols with phosphrous trihalides.
Answer
View full question & answer→$\rightarrow $ Alcohols react with phosphrous trihalides to give corresponded alkyl halides. This reaction is useful for preparation of alkyl halides from alcohols.
$3R-OH + PX_3 \rightarrow 3R-X + H_3PO_3 (X = Cl, Br)$
$3R-OH + PX_3 \rightarrow 3R-X + H_3PO_3 (X = Cl, Br)$
Question 122 Marks
Explain the reaction of alcohols with hydrogen halides. $\#\#\#$ Short note: Lucas test
Answer
View full question & answer→$\rightarrow$ Alcohols react with hydrogen halides to form alkyl halides.
$R - OH + HCl \xrightarrow{ ZnCl _2} R - Cl + H _2 O$
$\rightarrow$ The difference in reactivity of three classes of alcohols with $ \text{HCl}$ distinguishes them from one another.
$\rightarrow$ Alcohols are soluble in Lucas reagent $($conc. $ \text{HCl}$ and $ZnCl_2)$ while their halides are immiscible and produce turbidity in solution.
$\rightarrow$ In case of tertiary alcohols, turbidity is produced immediately as they form the halides easily.
$\rightarrow$ Primary alcohols do not produce turbidity at room temperature.
$\rightarrow$ This is how alcohols can be distinguished by Lucas test.
$R - OH + HCl \xrightarrow{ ZnCl _2} R - Cl + H _2 O$
$\rightarrow$ The difference in reactivity of three classes of alcohols with $ \text{HCl}$ distinguishes them from one another.
$\rightarrow$ Alcohols are soluble in Lucas reagent $($conc. $ \text{HCl}$ and $ZnCl_2)$ while their halides are immiscible and produce turbidity in solution.
$\rightarrow$ In case of tertiary alcohols, turbidity is produced immediately as they form the halides easily.
$\rightarrow$ Primary alcohols do not produce turbidity at room temperature.
$\rightarrow$ This is how alcohols can be distinguished by Lucas test.
Question 132 Marks
Write a note on acidity of phenols.
Answer
View full question & answer→→ Acidity of phenols: The reactions of phenol with metals (e.g., sodium, aluminium) and sodium hydroxide indicate its acidic nature. The hydroxyl group, in phenol is directly attached to 2 the sp hybridised carbon of benzene ring which acts as an electron withdrawing group. Due to this, the charge distribution in phenol molecule, as depicted in its resonance structures, causes the oxygen of -OH group to be positive
→ The reaction of phenol with aqueous sodium hydroxide indicates that phenols are stronger acids than alcohols and water.
→ The reaction of phenol with aqueous sodium hydroxide indicates that phenols are stronger acids than alcohols and water.
Question 142 Marks
'Alcohols are versatile compounds' discuss exaction of this statement by giving suitable example.
Answer
View full question & answer→→ Alcohols are versatile compounds. They react both as nucleophiles and electrophiles. The bond between O-H is broken when alcohols react as nucleophiles.
→ Alcohols as nucleophiles
(i)
(ii) The bond between C O is broken when they react as electrophiles. Protonated alcohols react in this manner.
→ Protonated alcohols as electrophiles
→ Alcohols as nucleophiles
(i)
(ii) The bond between C O is broken when they react as electrophiles. Protonated alcohols react in this manner.
→ Protonated alcohols as electrophiles
Question 152 Marks
How are alcohol compounds prepared by reduction of carboxylic acids and esters? Explain.
Answer
View full question & answer→$\rightarrow$ By reduction of carboxylic acids and esters :
Carboxylic acids are reduced to primary alcohls in excellent yields by lithium aluminium hydride, a strong reducing agent.
$RCOOH \xrightarrow[\text { (ii) } H _2 O ]{\text { (i) } LAH _4} RCH _2 OH$
$\rightarrow$ However, $LiAlH_{4,}$ is an expensive reagent and therefore, used for preparing special chemicals only. Commercially, acids are reduced to alcohols by converting them to esters followed by their reduction using hydrogen in the presence of catalyst $($catalytic hydrogenation$).$
$RCOOH \xrightarrow[ H ^{+}]{ R ^{\prime} OH } RCOOR' \xrightarrow[\text { Catalyst }]{ H _2} RCH _2 OH + R ^{\prime} OH$
Carboxylic acids are reduced to primary alcohls in excellent yields by lithium aluminium hydride, a strong reducing agent.
$RCOOH \xrightarrow[\text { (ii) } H _2 O ]{\text { (i) } LAH _4} RCH _2 OH$
$\rightarrow$ However, $LiAlH_{4,}$ is an expensive reagent and therefore, used for preparing special chemicals only. Commercially, acids are reduced to alcohols by converting them to esters followed by their reduction using hydrogen in the presence of catalyst $($catalytic hydrogenation$).$
$RCOOH \xrightarrow[ H ^{+}]{ R ^{\prime} OH } RCOOR' \xrightarrow[\text { Catalyst }]{ H _2} RCH _2 OH + R ^{\prime} OH$
Question 162 Marks
Explain the preparation of alcohol by reduction of aldehydes and ketones.
Answer
View full question & answer→$\rightarrow$ By reduction of aldehydes and ketones: Aldehydes and ketones are reduced to the correspoinding alcohols by addition of hydrogen in the presence of catalysts $($catalytic hydrogenation$).$ The usual catalyst is a finely divided metal such as platinum, palladium or nickel. It is also prepared by treating aldehydes and ketones with sodium borohydrode $(NaBH_4)$ or lithium aluminium hydride $(LiAlH_4).$
Aldehydes yield primary alcohols whereas ketones give secondary alcohols.
E.g.:
$(1)$
$(2)$
Aldehydes yield primary alcohols whereas ketones give secondary alcohols.
E.g.:
$(1)$
$(2)$
Question 172 Marks
How is the nomenclature of cyclic alcohol compound carried out? Give two examples.
Answer
View full question & answer→→ Cyclic alcohols are named using the prefix cyclo and considering the -OH group attached to C - 1.
Question 182 Marks
Discuss the classification of monohydric alcohols containing $C_{sp}^2-OH$ bond.
Answer
View full question & answer→$\rightarrow$ Compounds containing $C_{sp}^2-OH$ bond : These alcohols contain $-OH$ group bonded to a carbon$-$carbon double bond i.e., to a vinylic carbon or to an aryl carbon. These alcohols are also known as vinylic alcohols.
$\rightarrow$ Vinylic alcohol: $CH_2= CH - OH$
$\rightarrow$ Vinylic alcohol: $CH_2= CH - OH$
Question 192 Marks
Explain the classification of alcohols and phenols on the basis of number of hydroxyl groups.
Answer
View full question & answer→→ Alcohols and phenols may be classified as mono-, di, tri or polyhydric compounds depending on whether they contain one, two, three or many hydroxyl groups respectively in their structures as given below :
