General introduction of alcohol, Phenol and Ethers Questions in English

(N/A) Common naming of ethers: The names of the alkyl or aryl groups attached to the oxygen atom are written in alphabetical order,followed by the word 'ether'. If both groups are the same,the prefix 'di-' is used.
Examples:
$(i)$ $CH_3-O-C_2H_5$: Ethyl methyl ether
$(ii)$ $CH_3-O-CH(CH_3)_2$: Methyl isopropyl ether
$(iii)$ $C_2H_5-O-C_2H_5$: Diethyl ether
$IUPAC$ naming of ethers: Ethers are named as alkoxyalkanes. The smaller alkyl group is treated as part of the alkoxy group,while the larger alkyl group is treated as the parent alkane.
Examples:
$(i)$ $CH_3-O-CH_3$: Methoxymethane
$(ii)$ $CH_3-O-C_2H_5$: Methoxyethane
$(iii)$ $CH_3-O-CH_2CH_2CH_3$: $1-$Methoxypropane

(A-4, B-2, C-3, D-1) The correct matches are as follows:
$(A)$ One or more hydroxyl $(-OH)$ groups attached to an aliphatic carbon system define an $(4)$ Alcohol.
$(B)$ An $-OH$ group attached directly to an aromatic ring defines a $(2)$ Phenol.
$(C)$ When the hydrogen of the $-OH$ group in alcohols or phenols is replaced by an alkyl or aryl group,it forms an $(3)$ Ether ($R-O-R$ or $Ar-O-R$).
$(D)$ When the $-R$ group of an alcohol $(R-OH)$ is replaced by a hydrogen atom,it becomes $H-OH$,which is $(1)$ Water.
Therefore,the correct sequence is: $(A-4, B-2, C-3, D-1)$.

(N/A) The structures and bonding parameters for methanol, phenol, and methoxymethane are as follows:
$1$. Methanol $(CH_3OH)$:
- Structure: The oxygen atom is $sp^3$ hybridized. The $C-O-H$ bond angle is $108.9^{\circ}$, which is slightly less than the tetrahedral angle of $109^{\circ}28'$ due to lone pair-lone pair repulsion.
- Bond lengths: $C-O$ bond length is $142 \text{ pm}$ and $O-H$ bond length is $96 \text{ pm}$.
$2$. Phenol $(C_6H_5OH)$:
- Structure: The oxygen atom is attached to an $sp^2$ hybridized carbon of the benzene ring. The $C-O-H$ bond angle is $109^{\circ}$.
- Bond length: The $C-O$ bond length is $136 \text{ pm}$, which is shorter than in methanol due to the partial double bond character resulting from resonance with the benzene ring.
$3$. Methoxymethane $(CH_3OCH_3)$:
- Structure: The oxygen atom is $sp^3$ hybridized. The $C-O-C$ bond angle is $111.7^{\circ}$, which is larger than the tetrahedral angle due to the repulsion between the two bulky methyl groups.
- Bond length: The $C-O$ bond length is $141 \text{ pm}$.

(B) The molecular formula $C_4H_{10}O$ corresponds to saturated ethers or alcohols.
To find the ethers,we look for the functional group $R-O-R'$.
The possible ether isomers for $C_4H_{10}O$ are:
$1$. $CH_3-O-CH_2-CH_2-CH_3$ (Methoxypropane)
$2$. $CH_3-CH_2-O-CH_2-CH_3$ (Ethoxyethane)
$3$. $CH_3-O-CH(CH_3)_2$ ($2$-Methoxypropane)
Thus,there are $3$ isomers that are ethers.

(C) $IUPAC$ name: Benzene-$1, 2$-diol
Common name: catechol
The structure consists of a benzene ring with two hydroxyl $(-OH)$ groups at the ortho $(1, 2)$ positions.

(B) The molecular formula $C_4H_{10}O$ corresponds to several isomeric alcohols:
$A$. tert-butanol is the common name for $2$-methylpropan$-2$-ol. This is a correct pair.
$B$. tert-butanol is $2$-methylpropan$-2$-ol,not $1,1$-dimethylethan$-1$-ol. The name $1,1$-dimethylethan$-1$-ol is incorrect $IUPAC$ nomenclature for this structure. Thus,this pair is incorrect.
$C$. $n$-butanol is the common name for butan$-1$-ol. This is a correct pair.
$D$. isobutyl alcohol is the common name for $2$-methylpropan$-1$-ol. This is a correct pair.
Therefore,the correct combinations are $A$,$C$,and $D$.

(C) The structural isomeric alcohols with the molecular formula $C_4H_{10}O$ are:
$1.$ Butan$-1-$ol: $CH_3CH_2CH_2CH_2OH$
$2.$ Butan$-2-$ol: $CH_3CH_2CH(OH)CH_3$
$3.$ $2-$Methylpropan$-1-$ol: $(CH_3)_2CHCH_2OH$
$4.$ $2-$Methylpropan$-2-$ol: $(CH_3)_3COH$
Thus,the total number of structural isomers is $4$.

(A) In the carbinol system,alcohols are named as derivatives of methanol,which is called carbinol $(CH_3OH)$.
$sec$-Butyl alcohol has the structure $CH_3-CH_2-CH(OH)-CH_3$.
This can be viewed as a carbinol group $(CH_2OH)$ where two hydrogen atoms are replaced by an ethyl group $(-C_2H_5)$ and a methyl group $(-CH_3)$.
Therefore,the name is Ethyl methyl carbinol.

(A) The structure of crotonyl alcohol is $CH_3-CH=CH-CH_2OH$.
In this molecule,the $-OH$ group is attached to a carbon atom that is adjacent to a carbon-carbon double bond.
An alcohol in which the $-OH$ group is attached to an $sp^3$ hybridized carbon atom next to a $C=C$ double bond is classified as an allylic alcohol.
Therefore,crotonyl alcohol is an allylic alcohol.

(C) An allylic alcohol is defined as an alcohol where the $-OH$ group is attached to a $sp^3$ hybridized carbon atom that is directly bonded to a carbon-carbon double bond $(C=C)$.
In but-$2$-en-$1$-ol $(CH_3-CH=CH-CH_2OH)$,the $-OH$ group is attached to the $C_1$ atom,which is adjacent to the $C=C$ double bond at $C_2-C_3$. Thus,it is an allylic alcohol.

(D) Phenols are compounds in which a hydroxyl group $(-OH)$ is directly attached to a carbon atom of an aromatic ring (benzene ring).
In options $(A)$,$(B)$,and $(C)$,the $-OH$ group is directly attached to the aromatic ring,making them phenols.
In option $(D)$,the $-OH$ group is attached to a side-chain carbon atom (a methylene group,$-CH_2-$) which is then attached to the benzene ring. This compound is classified as an aromatic alcohol (specifically,benzyl alcohol).
Therefore,the compound in option $(D)$ is not a phenol.

(A) $Crotonyl$ alcohol is represented by the formula $CH_3CH=CHCH_2OH$.
In this molecule,the $-OH$ group is attached to a carbon atom that is $sp^3$ hybridized and is adjacent to a carbon-carbon double bond $(C=C)$.
This structural feature defines an allylic alcohol.

(B) In vinylic alcohol,the $-OH$ group is attached to a $sp^2$ hybridized carbon atom which is part of a carbon-carbon double bond.
In $but-2-en-2-ol$ $(CH_3-C(OH)=CH-CH_3)$,the $-OH$ group is directly attached to the $sp^2$ hybridized carbon of the double bond.
Therefore,$but-2-en-2-ol$ is a vinylic alcohol.

(D) phenolic $-OH$ group is defined as a hydroxyl group attached directly to an aromatic benzene ring.
$1$. Curcumin contains phenolic $-OH$ groups.
$2$. Eugenol contains a phenolic $-OH$ group.
$3$. Gallic acid ($3,4,5$-trihydroxybenzoic acid) contains phenolic $-OH$ groups.
$4$. Ascorbic acid (Vitamin $C$) is a lactone with enolic $-OH$ groups,but it does not contain a benzene ring,therefore it does not contain a phenolic $-OH$ group.

(C) Hydroquinone is a dihydric phenol where two hydroxyl $(-OH)$ groups are attached to the benzene ring at the $1$ and $4$ positions.
According to $IUPAC$ nomenclature,the parent chain is benzene,and the hydroxyl groups are indicated by the suffix $-diol$ at positions $1$ and $4$.
Therefore,the $IUPAC$ name is Benzene-$1,4$-diol.

(D) Phenols are organic compounds in which an $-OH$ group is directly attached to a carbon atom of an aromatic ring.
In option $A$,the $-OH$ group is attached to the benzene ring (o-Nitrophenol).
In option $B$,the $-OH$ group is attached to the naphthalene ring ($2$-Naphthol).
In option $C$,the $-OH$ group is attached to the benzene ring (p-Bromophenol).
In option $D$,the $-OH$ group is attached to a $CH_2$ group,which is then attached to the benzene ring. This compound is benzyl alcohol,which is an aromatic alcohol,not a phenol.

(D) The structures of the given acids are as follows:
$1$. Phthalic acid: $C_6H_4(COOH)_2$ (contains two $-COOH$ groups).
$2$. Adipic acid: $HOOC(CH_2)_4COOH$ (contains two $-COOH$ groups).
$3$. Glutaric acid: $HOOC(CH_2)_3COOH$ (contains two $-COOH$ groups).
$4$. Salicylic acid: $C_6H_4(OH)(COOH)$ (contains both $-OH$ and $-COOH$ groups).
Therefore,Salicylic acid is the correct answer.

(A) Eugenol is a chemical compound that is the primary component of clove oil. It is responsible for the characteristic aroma and flavor of cloves. Therefore,the correct source of Eugenol is $A$. Clove.

(A) The structure of $Benzene-1,2-diol$ consists of a benzene ring with two hydroxyl $(-OH)$ groups attached at adjacent positions ($1$ and $2$).
This compound is commonly known as $Catechol$ (or $Pyrocatechol$).

(C) In the carbinol system,alcohols are named as derivatives of methyl alcohol,which is referred to as $CH_3OH$ or carbinol.
For isobutyl alcohol,the structure is $(CH_3)_2CH-CH_2OH$.
This can be viewed as a carbinol group $(-CH_2OH)$ attached to an isopropyl group $((CH_3)_2CH-)$.
Therefore,the name according to the carbinol system is isopropyl carbinol.

(A) dihydric compound is one that contains two hydroxyl $(-OH)$ groups in its structure.
$1$. Crotonyl alcohol $(CH_3-CH=CH-CH_2OH)$ contains only one $-OH$ group,so it is a monohydric alcohol.
$2$. Resorcinol $(C_6H_4(OH)_2)$ contains two $-OH$ groups attached to the benzene ring,so it is a dihydric phenol.
$3$. Ethylene glycol $(HO-CH_2-CH_2-OH)$ contains two $-OH$ groups,so it is a dihydric alcohol.
$4$. Quinol $(C_6H_4(OH)_2)$ contains two $-OH$ groups attached to the benzene ring,so it is a dihydric phenol.
Therefore,Crotonyl alcohol is not a dihydric compound.

(A) The common name 'propylene glycol' refers to the chemical compound $CH_3-CH(OH)-CH_2OH$.
Its $IUPAC$ name is determined by identifying the longest carbon chain containing the hydroxyl groups,which is a propane chain ($3$ carbons).
The hydroxyl groups are attached at positions $1$ and $2$.
Therefore,the $IUPAC$ name is Propane-$1,2$-diol.

(D) The given compound is a benzene ring substituted with a hydroxyl group $(-OH)$ and a bromine atom $(-Br)$ at the para position relative to each other.
According to $IUPAC$ nomenclature rules,the hydroxyl group attached to a benzene ring is given priority,and the parent compound is named as phenol.
The carbon atom attached to the $-OH$ group is assigned position $1$.
Counting from this position,the bromine atom is at position $4$.
Therefore,the $IUPAC$ name is $4-$bromophenol.

(A) Catechol is a common name for a dihydroxybenzene derivative where the two hydroxyl $(-OH)$ groups are attached to adjacent carbon atoms on the benzene ring.
According to $IUPAC$ nomenclature rules,the benzene ring is numbered such that the substituents get the lowest possible locants.
For catechol,the $-OH$ groups are at positions $1$ and $2$.
Therefore,the correct $IUPAC$ name is Benzene-$1,2$-diol.

(D) simple or symmetrical ether is one in which both alkyl or aryl groups attached to the oxygen atom are the same.
In $CH_3-O-CH_3$ (Methoxymethane),both groups attached to the oxygen atom are methyl groups $(-CH_3)$.
Therefore,it is a simple ether.

(B) Ethers are organic compounds characterized by an oxygen atom connected to two alkyl or aryl groups,represented by the general formula $R-O-R'$. The functional group present in ethers is the ether linkage,which is represented as $-O-$.

(C) Anisole is an ether with the chemical formula $C_6H_5OCH_3$.
In $IUPAC$ nomenclature,ethers are named as alkoxyalkanes.
Here,the benzene ring is the parent hydrocarbon,and the $-OCH_3$ group is the methoxy substituent.
Therefore,the $IUPAC$ name is methoxybenzene.

(B) Catechol is a common name for a dihydroxybenzene derivative where the two hydroxyl $(-OH)$ groups are attached to adjacent carbon atoms on the benzene ring.
According to $IUPAC$ nomenclature,the benzene ring is numbered such that the substituents receive the lowest possible locants.
For catechol,the $-OH$ groups are at positions $1$ and $2$.
Therefore,the $IUPAC$ name is Benzene-$1,2$-diol.

(C) The given compound is an ether: $CH_3-CH_2-O-CH_2-CH(CH_3)_2$.
To name it according to $IUPAC$ rules,we identify the longest carbon chain attached to the oxygen atom.
The longest chain has $3$ carbon atoms,which is a propane chain.
The ethoxy group $(-OCH_2CH_3)$ is attached to the first carbon of this chain.
There is a methyl group $(-CH_3)$ attached to the second carbon of the propane chain.
Thus,the $IUPAC$ name is $1-$ethoxy$-2-$methylpropane.

(B) An allylic alcohol is an alcohol in which the $-OH$ group is attached to a $sp^3$ hybridized carbon atom adjacent to a carbon-carbon double bond $(C=C)$.
In $But-3-en-2-ol$ $(CH_2=CH-CH(OH)-CH_3)$, the $-OH$ group is attached to the carbon atom adjacent to the double bond, which satisfies the definition of an allylic alcohol.

(A) The correct answer is $A$ (Ether).
An ether functional group has the general structure $R-O-R'$,where $R$ and $R'$ are alkyl or aryl groups.
It does not contain a carbonyl group $(>C=O)$.
In contrast,esters $(R-CO-OR')$,amides $(R-CO-NH_2)$,and acyl halides $(R-CO-X)$ all contain the carbonyl group $(>C=O)$.

(B) An allylic alcohol is one in which the hydroxyl group $(-OH)$ is attached to a $sp^3$ hybridized carbon atom adjacent to a carbon-carbon double bond.
$A$ primary $(1^\circ)$ allylic alcohol has the $-OH$ group attached to a primary carbon atom (a carbon atom bonded to only one other carbon atom) that is adjacent to a double bond.
Analyzing the options:
$(A)$ $H_2C=CH-CH(CH_3)-OH$: The $-OH$ is on a secondary carbon. This is a secondary allylic alcohol.
$(B)$ $H_2C=CH-CH_2OH$: The $-OH$ is on a primary carbon $(CH_2)$ adjacent to the $C=C$ bond. This is a primary allylic alcohol.
$(C)$ $H_2C=CH-C(CH_3)_2-OH$: The $-OH$ is on a tertiary carbon. This is a tertiary allylic alcohol.
$(D)$ $H_3C-CH=CH-CH(CH_3)-OH$: The $-OH$ is on a secondary carbon. This is a secondary allylic alcohol.
Therefore,the correct option is $(B)$.

(B) The structure of $Benzene-1,3-diol$ consists of a benzene ring with two hydroxyl $(-OH)$ groups attached at the $1$ and $3$ positions.
This compound is commonly known as $resorcinol$.
- $Catechol$ is $Benzene-1,2-diol$.
- $Quinol$ (or $hydroquinone$) is $Benzene-1,4-diol$.
- $Pyrogallol$ is $Benzene-1,2,3-triol$.
Therefore,the correct option is $B$.

(D) An alcohol is defined as a compound in which a hydroxyl group $(-OH)$ is attached to an $sp^3$ hybridized carbon atom.
In options $A$,$B$,and $C$,the $-OH$ group is directly attached to the benzene ring,where the carbon atom is $sp^2$ hybridized. These compounds are classified as phenols.
In option $D$,the $-OH$ group is attached to a $-CH_2-$ group,which is attached to the benzene ring. The carbon atom bonded to the $-OH$ group is $sp^3$ hybridized. Therefore,it is an alcohol (specifically,a primary benzylic alcohol).

(A) An ether is an organic compound characterized by an oxygen atom connected to two alkyl or aryl groups,represented by the general formula $R-O-R'$.
Methoxymethane $(CH_3-O-CH_3)$ contains an oxygen atom bonded to two methyl groups,which fits the definition of an ether.
Propan$-2-$ol is an alcohol,while Benzenol and Benzene$-1,2-$diol are phenols.

(C) The structure of $Crotonyl$ alcohol is $CH_3-CH=CH-CH_2-OH$.
In this molecule,the $-OH$ group is attached to a $sp^3$ hybridized carbon atom,which is adjacent to a carbon-carbon double bond $(C=C)$.
Compounds in which the $-OH$ group is attached to a $sp^3$ hybridized carbon atom next to a double bond are classified as allylic alcohols.
Therefore,$Crotonyl$ alcohol is an example of an allylic alcohol.

(B) The structure of $Benzene-1, 2, 3-triol$ consists of a benzene ring with three hydroxyl $(-OH)$ groups attached at the $1, 2,$ and $3$ positions.
Its common name is $Pyrogallol$.

(B) Anisole is an aromatic ether with the chemical formula $C_6H_5OCH_3$.
According to $IUPAC$ nomenclature,ethers are named as alkoxyalkanes.
In this structure,a methoxy group $(-OCH_3)$ is attached to a benzene ring.
Therefore,the $IUPAC$ name of anisole is methoxybenzene.

(B) Resorcinol is a dihydric phenol in which two hydroxyl $(-OH)$ groups are attached to the benzene ring at the $1$ and $3$ positions.
Its $IUPAC$ name is benzene-$1, 3$-diol.
Option $B$ correctly represents this structure.

(D) Catechol is a dihydroxy benzene where the two hydroxyl groups are at the ortho position relative to each other,which corresponds to $Benzene-1,2-diol$.
$m$-Cresol is a methyl-substituted phenol where the methyl group is at the meta position relative to the hydroxyl group,which corresponds to $3-Methyl phenol$.

(B) The structures are identified as follows:
$a$: Phenetole $(C_6H_5OCH_2CH_3)$
$b$: Catechol (benzene$-1,2-$diol)
$c$: Resorcinol (benzene$-1,3-$diol)
$d$: $o-$cresol ($2$-methylphenol)
$e$: Anisole $(C_6H_5OCH_3)$
Matching the compounds:
$A$ ($o-$cresol) corresponds to $d$.
$B$ (catechol) corresponds to $b$.
$C$ (Phenetole) corresponds to $a$.
$D$ (resorcinol) corresponds to $c$.
Thus,the correct matching is $A-d, B-b, C-a, D-c$.

(B) Benzylic alcohols are those in which the hydroxyl group $(-OH)$ is attached to a carbon atom next to an aromatic ring (a benzylic carbon).
In $1-$Phenylpropan$-1-$ol $(C_6H_5-CH(OH)-CH_2-CH_3)$,the $-OH$ group is attached to the carbon atom directly bonded to the benzene ring,which is the benzylic position.
Therefore,it is a benzylic alcohol.

(B) The general molecular formula for saturated acyclic alcohols is $C_n H_{2n+2} O$.
This formula indicates that the compound is saturated (no double or triple bonds).
Ethers also have the general molecular formula $C_n H_{2n+2} O$ and are saturated.
Therefore,alcohols and ethers with the same number of carbon atoms are functional isomers of each other.

(B) $1$. Identify the longest carbon chain attached to the oxygen atom. The chain has $5$ carbon atoms,so the parent alkane is pentane.
$2$. The phenoxy group $(-OC_6H_5)$ is attached to the first carbon of the pentane chain.
$3$. Number the chain starting from the carbon attached to the oxygen atom to give the lowest possible number to the substituent.
$4$. The methyl group is at the $4^{th}$ position.
$5$. Thus,the $IUPAC$ name is $1-$phenoxy$-4-$methylpentane.
$6$. However,based on the provided options and the structure,the compound is named as an ether derivative of benzene where the alkoxy group is $4-$methylpentoxy. Therefore,the name is $4-$methylpentoxybenzene.

(A) Benzene-$1,3$-diol consists of a benzene ring with two hydroxyl $(-OH)$ groups attached at the $1$ and $3$ positions.
Common names for dihydroxybenzenes are:
$1,2$-dihydroxybenzene is known as Catechol.
$1,3$-dihydroxybenzene is known as Resorcinol.
$1,4$-dihydroxybenzene is known as Hydroquinol (or Quinol).
Therefore,the correct common name for benzene-$1,3$-diol is Resorcinol.

(D) The molecular formula $C_4H_{10}O$ corresponds to ethers. An unsymmetrical ether has different alkyl groups attached to the oxygen atom.
For $C_4H_{10}O$,the possible unsymmetrical ethers are:
$1$. $CH_3-O-CH_2CH_2CH_3$ (methoxypropane)
$2$. $CH_3-O-CH(CH_3)_2$ ($2$-methoxypropane)
Among the given options,$methoxypropane$ is an unsymmetrical ether with the formula $C_4H_{10}O$.

(A) The structure of methyl isopropyl ether is $\text{CH}_3-\text{O}-\text{CH}(\text{CH}_3)_2$.
In $IUPAC$ nomenclature for ethers,the smaller alkyl group is treated as an alkoxy substituent attached to the longer alkane chain.
Here,the longest carbon chain is propane ($3$ carbons).
The methoxy group $(-\text{OCH}_3)$ is attached to the $2$nd carbon atom of the propane chain.
Therefore,the $IUPAC$ name is $2$-methoxypropane.