General introduction of alcohol, Phenol and Ethers Questions in English

(D) Lewis base is defined as a substance that can donate a lone pair of electrons.
In $ROH$ (alcohol),the oxygen atom possesses two lone pairs of electrons,which it can donate to an electron-deficient species.
Therefore,$ROH$ acts as a Lewis base.
$CO_2$,$SO_3$,and $SO_2$ are Lewis acids because they are electron-deficient and can accept electron pairs.

(A) The functional group $-OH$ represents an alcohol group.
$1, 2-$ethanediol,with the formula $HO-CH_2-CH_2-OH$,contains two hydroxyl $(-OH)$ groups.
$2-$butanone is a ketone,Nitrobenzene is a nitro compound,and Ethanal is an aldehyde.

(D) Glycerol $(CH_2(OH)-CH(OH)-CH_2(OH))$ contains three hydroxyl $(-OH)$ groups attached to three different carbon atoms.
Therefore,it is classified as a trihydric alcohol.

(A) Cresols are methylphenols,which are compounds consisting of a methyl group attached to a benzene ring along with a hydroxyl group.
They are commonly referred to as hydroxy toluenes.
The structure of $o$-cresol is shown in the image,where a $-CH_3$ group and an $-OH$ group are attached to the benzene ring.
Therefore,the correct option is $(A)$.

(C) The structure of ortho-dihydroxy benzene consists of a benzene ring with two hydroxyl $(-OH)$ groups attached at adjacent positions (ortho positions).
This compound is commonly known as catechol.

(B) The term $Carbinol$ is the common name used for $Methanol$ $(CH_3OH)$.
It is the simplest alcohol where a hydroxyl group $(-OH)$ is attached to a methyl group $(-CH_3)$.

(C) primary alcohol is defined as an alcohol in which the hydroxyl group $(-OH)$ is attached to a primary carbon atom (a carbon atom attached to only one other carbon atom or to no other carbon atoms).
Therefore,the functional group characteristic of a primary alcohol is represented by the structure $-CH_2OH$.

(A) The structure of $1, 2, 3$-trihydroxybenzene consists of a benzene ring with three hydroxyl $(-OH)$ groups attached at the $1, 2,$ and $3$ positions.
This specific isomer of trihydroxybenzene is commonly known as $Pyrogallol$.

(B) secondary alcohol is an alcohol where the hydroxyl group $(-OH)$ is attached to a carbon atom that is bonded to two other carbon atoms.
This is represented by the characteristic group $ >CHOH $.

(B) The compound $HO-CH_2-CH_2-OH$ is a dihydric alcohol with two hydroxyl groups attached to adjacent carbon atoms.
Its $IUPAC$ name is $Ethane-1,2-diol$,and its common name is $Ethylene \ glycol$.

(A) Cyclohexanol is a cyclic alcohol with the molecular formula $C_6H_{11}OH$.
It consists of a saturated six-membered ring (cyclohexane ring) where one hydrogen atom is replaced by a hydroxyl $(-OH)$ group.
The structure shown in option $A$ correctly represents this,where the ring is fully saturated and has an $-OH$ group attached.

(A) Methanol is also referred to as wood alcohol or wood spirit or wood naphtha because the earliest method for its preparation was by the destructive distillation of wood.

(A) An ether is classified as a simple or symmetrical ether if the two alkyl or aryl groups attached to the oxygen atom are the same.
In $CH_3OCH_3$ (dimethyl ether),both groups attached to the oxygen atom are methyl groups $(-CH_3)$.
Therefore,$CH_3OCH_3$ is a simple ether.

(C) The functional group $'-O-'$ represents an ether,which has the general formula $R-O-R'$.
Diethyl ether $(C_2H_5-O-C_2H_5)$ contains this functional group and is a classic example of an ether.

(A) The given compound is $(CH_3)_2CH-O-CH_2-CH_2-CH_3$.
In this ether,the oxygen atom is bonded to an isopropyl group $(CH_3)_2CH-$ and a propyl group $-CH_2-CH_2-CH_3$.
According to the common nomenclature system for ethers,the alkyl groups are named in alphabetical order followed by the word 'ether'.
Since 'Isopropyl' starts with '$I$' and 'Propyl' starts with '$P$',the common name is Isopropyl propyl ether.

(A) The term $mercaptans$ is the common name used for $thio-alcohols$ (also known as $thiols$),which have the general formula $R-SH$.

(A) Epoxides are three-membered cyclic ethers containing an oxygen atom in the ring.
For example,ethylene oxide is represented as:
$CH_2-CH_2$
$|$
$O$

(D) Phenol $(C_6H_5OH)$ was discovered by Runge in the middle oil fraction of coal-tar distillation.
It was named 'carbolic acid' (from Latin $carbo$ meaning coal and $oleum$ meaning oil).
In its pure form,it is a white crystalline solid,but it is often found as a liquid containing $5\%$ water at room temperature,which is commonly referred to as carbolic acid.

(C) $1$. Identify the longest carbon chain containing the functional group $(-OH)$. The structure is $(CH_3CH_2)_3C-OH$.
$2$. The longest chain containing the $-OH$ group has $5$ carbon atoms,which is a pentane derivative.
$3$. Numbering the chain from either end gives the $-OH$ group at the $3^{rd}$ position.
$4$. There is an ethyl group attached at the $3^{rd}$ carbon atom.
$5$. Therefore,the $IUPAC$ name is $3-$ethylpentan$-3-$ol.

(B) Metamers are isomers that have the same molecular formula but differ in the distribution of alkyl groups on either side of the functional group (in this case,the ether oxygen atom).
Diethyl ether has the formula $C_2H_5-O-C_2H_5$ (molecular formula $C_4H_{10}O$).
$2-$Methoxypropane has the formula $CH_3-O-CH(CH_3)_2$ (molecular formula $C_4H_{10}O$).
Since both compounds have the same molecular formula but different alkyl groups attached to the oxygen atom (ethyl-ethyl in diethyl ether vs. methyl-isopropyl in $2-$methoxypropane),they are metamers.

(D) Alkanols are alcohols with the general formula $C_nH_{2n+1}OH$.
Expanding this,we get $C_nH_{2n+1+1}O$,which simplifies to $C_nH_{2n+2}O$.
Therefore,the general formula for the homologous series of alkanols is $C_nH_{2n+2}O$.

(D) symmetrical or simple ether is an ether in which the same alkyl or aryl group is attached to both sides of the oxygen atom.
In the structure $(CH_3)_2CH-O-CH(CH_3)_2$,the oxygen atom is bonded to two identical isopropyl groups.
Therefore,it is a symmetrical ether.

(C) Ethyl methyl ether consists of an ethyl group $(-CH_2CH_3)$ and a methyl group $(-CH_3)$ attached to an oxygen atom.
Both $CH_3 - CH_2 - O - CH_3$ and $CH_3 - O - CH_2 - CH_3$ represent the same molecule,as the oxygen atom is simply connected to one ethyl and one methyl group in both representations.
Therefore,both representations are correct.

(B) The name 'cyclohexyl alcohol' refers to cyclohexanol,which consists of a hydroxyl group $(-OH)$ attached directly to a cyclohexane ring.
Option $A$ shows cyclohexylmethanol $(C_6H_{11}CH_2OH)$.
Option $B$ shows cyclohexanol $(C_6H_{11}OH)$.
Option $C$ shows cyclohexane $(C_6H_{12})$.

(B) $1$. Identify the longest carbon chain containing the functional group $(-OH)$. The longest chain has $5$ carbon atoms,so the parent alkane is pentane.
$2$. Number the chain from the end that gives the lowest number to the carbon attached to the $-OH$ group. Numbering from either side gives the $-OH$ group at position $3$.
$3$. The structure is $CH_3CH_2-C(CH_3)(OH)-CH_2CH_3$.
$4$. The longest chain is $5$ carbons long (pentane).
$5$. There is a methyl group at position $3$.
$6$. The $-OH$ group is at position $3$.
$7$. Therefore,the $IUPAC$ name is $3-$methylpentan$-3-$ol or $3-$methyl$-3-$pentanol.

(C) secondary alcohol is defined by the presence of a hydroxyl group $(-OH)$ attached to a carbon atom that is bonded to two other carbon atoms. The characteristic structural group is represented as $>CHOH$.

(D) Compounds in which the $OH$ group is directly attached to the benzene ring are called phenols.
Benzenol (phenol),cresol (methylphenol),and catechol (benzene$-1,2-$diol) all contain an $OH$ group attached to a benzene ring.
Therefore,all of the given compounds are phenols.

(B) Compounds in which the $-OH$ group is directly attached to the benzene ring are called phenols.

(C) Cumene is the common name for $Isopropylbenzene$.
Its chemical structure consists of a benzene ring attached to an isopropyl group,represented as $C_6H_5CH(CH_3)_2$.
It is widely used as a precursor in the industrial production of phenol and acetone.

(A) $Phenol$ $(C_6H_5OH)$ is commonly known as carbolic acid. An aqueous solution of phenol is often referred to as carbolic acid.

(D) dihydric alcohol is an alcohol that contains two hydroxyl $(-OH)$ groups.
Ethylene glycol,with the formula $HO-CH_2-CH_2-OH$,is a classic example of a dihydric alcohol.
Catechol and resorcinol are dihydric phenols,not alcohols.
Glycerol is a trihydric alcohol.

(B) Alcohols and ethers with the same molecular formula are functional isomers of each other. For example,$CH_3CH_2OH$ (ethanol) and $CH_3OCH_3$ (dimethyl ether) both have the molecular formula $C_2H_6O$.

(B) The molecular formula $C_4H_{10}O$ corresponds to the following ether isomers:
$1$. $CH_3-O-CH_2CH_2CH_3$ (Methyl propyl ether)
$2$. $CH_3-O-CH(CH_3)_2$ (Methyl isopropyl ether)
$3$. $CH_3CH_2-O-CH_2CH_3$ (Diethyl ether)
Thus,there are $3$ possible ether isomers.

(C) Alkanols are derivatives of alkanes,formed by replacing one hydrogen atom $(-H)$ of an alkane with a hydroxyl group $(-OH)$.
The general formula for alkanes is $C_nH_{2n+2}$.
Replacing one $H$ with $OH$ gives $C_nH_{2n+1}OH$,which simplifies to $C_nH_{2n+2}O$.
Therefore,the general molecular formula for the homologous series of alkanols is $C_nH_{2n+2}O$.

(A) Alkanols (alcohols) are derivatives of alkanes where one hydrogen atom is replaced by a hydroxyl $(-OH)$ group.
The general formula for an alkane is $C_nH_{2n+2}$.
Replacing one $H$ with $OH$ gives $C_nH_{2n+1}OH$,which simplifies to $C_nH_{2n+2}O$.
Thus,the correct general molecular formula is $C_nH_{2n+2}O$.

(D) In structure $(a)$,the $-OH$ group is attached to a carbon atom that is bonded to two other carbon atoms,making it a secondary alcohol.
In structure $(b)$,the $-OH$ group is attached to a carbon atom that is bonded to only one other carbon atom,making it a primary alcohol.
Therefore,$(a)$ is a secondary alcohol and $(b)$ is a primary alcohol.

(C) The question refers to epoxides,which are cyclic ethers.
Epoxides undergo ring-opening reactions via the $S_N2$ mechanism.
In basic conditions,the nucleophile attacks the less sterically hindered carbon atom of the epoxide ring via $S_N2$.
In acidic conditions,the oxygen atom is protonated,which increases the electrophilicity of the ring carbons. Even in acidic conditions,the reaction proceeds via an $S_N2$-like mechanism where the nucleophile attacks the more substituted carbon if it has significant carbocation character,or the less substituted carbon due to steric factors.
However,for simple epoxides like propylene oxide $(CH_3-CH-CH_2-O)$,the $S_N2$ pathway is dominant in both conditions.
The options $A$ and $B$ are simple ethers,not epoxides,and do not typically undergo ring-opening $S_N2$ reactions.
Therefore,the epoxide structure provided in option $C$ is the correct answer.

(C) $1$. Identify the principal functional group: The $-OH$ group attached to the benzene ring makes it a phenol,which is the parent compound.
$2$. Number the ring: The carbon atom attached to the $-OH$ group is assigned position $1$.
$3$. Number the substituents: The two methyl groups are at positions $2$ and $6$.
$4$. Combine: The name is $2,6-$ dimethylphenol.

(A) The structural formula of diethyl ether $(C_2H_5OC_2H_5)$ is $CH_3-CH_2-O-CH_2-CH_3$.
To count the total number of $\sigma$-bonds,we count all single bonds in the molecule:
- There are $10$ $C-H$ bonds.
- There are $2$ $C-C$ bonds.
- There are $2$ $C-O$ bonds.
Total number of $\sigma$-bonds = $10 + 2 + 2 = 14$.

(D) Grignard reagents $(R-Mg-X)$ are organometallic compounds that are highly reactive towards protic sources like water $(H_2O)$,alcohols $(R-OH)$,or acids $(R-COOH)$.
When a Grignard reagent reacts with water,it undergoes a rapid acid-base reaction to form an alkane $(R-H)$ and a metal hydroxide halide $(Mg(OH)X)$.
The reaction is: $R-Mg-X + H_2O \rightarrow R-H + Mg(OH)X$.
Therefore,the presence of water destroys the Grignard reagent,making ether an essential non-protic solvent for its preparation.

(A) Cumene is the common name for $Isopropylbenzene$.
Its chemical structure is $C_6H_5CH(CH_3)_2$.
It is an important intermediate in the industrial production of phenol and acetone.

(N/A) To classify alcohols,we look at the carbon atom to which the $-OH$ group is attached:
$1$. Primary $(1^{\circ})$ alcohol: The $-OH$ group is attached to a carbon atom bonded to only one other carbon atom.
- $(i)$ $CH_3-C(CH_3)_2-CH_2OH$: The $-CH_2OH$ carbon is attached to one quaternary carbon.
- $(ii)$ $CH_2=CH-CH_2OH$: The $-CH_2OH$ carbon is attached to one $sp^2$ hybridized carbon.
- $(iii)$ $CH_3-CH_2-CH_2-OH$: The $-CH_2OH$ carbon is attached to one primary carbon.
$2$. Secondary $(2^{\circ})$ alcohol: The $-OH$ group is attached to a carbon atom bonded to two other carbon atoms.
- $(iv)$ $C_6H_5-CH(OH)-CH_3$: The $-CH(OH)-$ carbon is attached to a phenyl group and a methyl group.
- $(v)$ $C_6H_5-CH_2-CH(OH)-CH_3$: The $-CH(OH)-$ carbon is attached to a $-CH_2C_6H_5$ group and a methyl group.
$3$. Tertiary $(3^{\circ})$ alcohol: The $-OH$ group is attached to a carbon atom bonded to three other carbon atoms.
- $(vi)$ $C_6H_5-CH=CH-C(OH)(CH_3)_2$: The $-C(OH)-$ carbon is attached to two methyl groups and one alkenyl group.

(B) An allylic alcohol is an alcohol in which the hydroxyl group $(-OH)$ is attached to a carbon atom that is adjacent to a carbon-carbon double bond $(C=C)$.
Based on the structural definitions,the alcohols identified as $(ii)$ and $(vi)$ contain the $-OH$ group attached to an $sp^3$ hybridized carbon atom next to a $C=C$ double bond,thus they are classified as allylic alcohols.

(A) $(i)$ $2,2,4-Trimethylpentan-3-ol$
$(ii)$ $5-Ethylheptane-2,4-diol$
$(iii)$ $Butane-2,3-diol$
$(iv)$ $Propane-1,2,3-triol$
$(v)$ $2-Methylphenol$
$(vi)$ $4-Methylphenol$
$(vii)$ $2,5-Dimethylphenol$
$(viii)$ $2,6-Dimethylphenol$
$(ix)$ $1-Methoxy-2-methylpropane$
$(x)$ $Ethoxybenzene$
$(xi)$ $1-Phenoxyheptane$
$(xii)$ $2-Ethoxybutane$

(N/A) $(i)$ $CH_3-C(OH)(CH_3)-CH_2-CH_3$
$(ii)$ $C_6H_5-CH_2-CH(OH)-CH_3$
$(iii)$ $HO-CH_2-CH_2-C(OH)(CH_3)-CH_2-C(OH)(CH_3)-CH_3$
$(iv)$ $2,3-$Diethylphenol structure with $-OH$ at position $1$ and $-C_2H_5$ groups at positions $2$ and $3$ on the benzene ring.
$(v)$ $CH_3-CH_2-O-CH_2-CH_2-CH_3$
$(vi)$ $CH_3-CH_2-O-CH(CH_3)-CH(CH_3)-CH_2-CH_3$
$(vii)$ Cyclohexane ring attached to $-CH_2OH$
$(viii)$ $CH_3-CH_2-C(OH)(C_6H_{11})-CH_2-CH_3$
$(ix)$ Cyclopentene ring with $-OH$ at position $1$ and double bond at position $3$
$(x)$ $Cl-CH_2-CH_2-CH(C_2H_5)-CH_2-OH$

(N/A) Alcohols and phenols are formed by the replacement of a hydrogen atom in an aliphatic and aromatic hydrocarbon,respectively,by a hydroxyl $(-OH)$ group.
Ethers are formed by the replacement of the hydrogen atom in a hydrocarbon by an alkoxy or aryloxy group. Alternatively,ethers can be visualized as the replacement of the hydrogen atom of the $-OH$ group of an alcohol or phenol by an alkyl or aryl group.
Alcohols contain one or more than one $-OH$ group$(s)$ bonded directly to carbon atom$(s)$ of an aliphatic system (e.g.,$CH_3OH$).
Phenols contain one or more than one $-OH$ group$(s)$ bonded directly to the $sp^2$ hybridized carbon of an aromatic system (e.g.,$C_6H_5OH$).
Applications:
Ethanol is used for polishing wooden furniture and is commonly known as ordinary spirit.
Many essential compounds like sugar,cotton in fabrics,and paper are made of compounds containing $-OH$ groups.

(N/A) Alcohols and phenols can be classified as mono-,di-,tri-,or polyhydric compounds depending on whether they contain one,two,three,or many hydroxyl $(-OH)$ groups respectively in their structures.
$1$. Monohydric alcohols: Contain one $-OH$ group. Example: Ethanol $(C_2H_5OH)$.
$2$. Dihydric alcohols: Contain two $-OH$ groups. Example: Ethane-$1,2$-diol $(CH_2OH-CH_2OH)$.
$3$. Trihydric alcohols: Contain three $-OH$ groups. Example: Propane-$1,2,3$-triol $(CH_2OH-CHOH-CH_2OH)$.

(N/A) Ethers are classified into two main categories based on the nature of the alkyl or aryl groups attached to the oxygen atom:
$1$. Symmetrical Ethers (Simple Ethers): In these ethers,the two alkyl or aryl groups attached to the oxygen atom are the same. For example,$CH_3-O-CH_3$ (Dimethyl ether) and $C_6H_5-O-C_6H_5$ (Diphenyl ether).
$2$. Unsymmetrical Ethers (Mixed Ethers): In these ethers,the two alkyl or aryl groups attached to the oxygen atom are different. For example,$CH_3-O-C_2H_5$ (Ethyl methyl ether) and $CH_3-O-C_6H_5$ (Methyl phenyl ether or Anisole).

(N/A) Common name of alcohol: To write the common name of alcohols,the name of the alkyl group attached to the hydroxyl group is written,followed by the word 'alcohol'.
$(b)$ $IUPAC$ nomenclature of alcohols:
$(i)$ Monohydric alcohols: In the $IUPAC$ system,the name of a monohydric alcohol is derived from the corresponding alkane by replacing the terminal $'e'$ with the suffix $'-ol'$.
$\Rightarrow$ The position of substituents is indicated by numbers $(1, 2, . . .)$.
$\Rightarrow$ The longest carbon chain (parent chain) is numbered starting from the end that gives the lowest possible number to the carbon atom attached to the hydroxyl group.
$\Rightarrow$ The positions of the $-OH$ group and other substituents are indicated by the numbers of the carbon atoms to which they are attached.
$(ii)$ Polyhydric alcohols: For $IUPAC$ names of polyhydric alcohols,the terminal $'e'$ of the alkane name is retained,and the suffix $'-ol'$ is added. The number of $-OH$ groups is indicated by prefixes like 'di','tri',etc.,before the suffix 'ol'.
Example: $CH_2OH-CH_2OH$ (Ethane-$1,2$-diol),$CH_2OH-CHOH-CH_2OH$ (Propane-$1,2,3$-triol).

(N/A) The common and $\text{IUPAC}$ names are provided in the table below:
| No. | Compound | Common Name | $\text{IUPAC}$ Name |
| :--- | :--- | :--- | :--- |
| $(i)$ | $CH_3OH$ | Methyl alcohol | Methanol |
| $(ii)$ | $CH_3CH_2CH_2OH$ | $n$-Propyl alcohol | Propan$-1-$ol |
| $(iii)$ | $CH_3CH(OH)CH_3$ | Isopropyl alcohol | Propan$-2-$ol |
| $(iv)$ | $CH_3CH_2CH_2CH_2OH$ | $n$-Butyl alcohol | Butan$-1-$ol |
| $(v)$ | $CH_3CH(OH)CH_2CH_3$ | sec-Butyl alcohol | Butan$-2-$ol |
| $(vi)$ | $(CH_3)_2CHCH_2OH$ | Isobutyl alcohol | $2-$Methylpropan$-1-$ol |
| $(vii)$ | $(CH_3)_3C-OH$ | tert-Butyl alcohol | $2-$Methylpropan$-2-$ol |
| $(viii)$ | $HOCH_2CH_2OH$ | Ethylene glycol | Ethane$-1,2-$diol |
| $(ix)$ | $CH_2OHCH(OH)CH_2OH$ | Glycerol (Glycerin) | Propane$-1,2,3-$triol |
| $(x)$ | $CH_3CH_2OH$ | Ethyl alcohol | Ethanol |