Following characteristics absorption bands are obtained in IR spectrum of an organic compound having molecular formula $C_{2}H_{6}O$:
(a) Strong band at $3300~cm^{-1}$
(b) Medium intensity band at $2965 cm^{-1}$
(c) Strong band at $2920~cm^{-1}$
(d) a band at $1050~cm^{-1}$.
Identify the compound:

Question

Following characteristics absorption bands are obtained in IR spectrum of an organic compound having molecular formula $C_{2}H_{6}O$: 
(a) Strong band at $3300~cm^{-1}$ 
(b) Medium intensity band at $2965 cm^{-1}$ 
(c) Strong band at $2920~cm^{-1}$ 
(d) a band at $1050~cm^{-1}$. 
Identify the compound:

Accepted Answer

The given IR spectrum characteristics for the organic compound with the molecular formula $C_{2}H_{6}O$ are as follows:

(a) A strong band at $3300~cm^{-1}$: This band is indicative of an O-H stretching vibration, which is characteristic of alcohols. The presence of this band strongly suggests the presence of an alcohol group in the compound.

(b) A medium intensity band at $2965~cm^{-1}$: This band corresponds to C-H stretching vibrations, which are common in alkanes and other organic compounds containing C-H bonds.

(c) A strong band at $2920~cm^{-1}$: Similar to the band at $2965~cm^{-1}$, this band also indicates C-H stretching vibrations.

(d) A band at $1050~cm^{-1}$: This band is typically associated with C-O stretching vibrations, which are present in alcohols and ethers.

Now, let's analyze why Option 2 ($CH_{3}CH_{2}OH$, ethanol) is the correct answer:

1. **Presence of O-H Group**: The strong band at $3300~cm^{-1}$ is characteristic of the O-H stretching vibration found in alcohols. Ethanol ($CH_{3}CH_{2}OH$) contains an O-H group, which explains this absorption band.

2. **C-H Stretching**: The bands at $2965~cm^{-1}$ and $2920~cm^{-1}$ are consistent with the C-H stretching vibrations found in ethanol, which has both methyl and methylene groups.

3. **C-O Stretching**: The band at $1050~cm^{-1}$ corresponds to the C-O stretching vibration, which is present in ethanol due to the alcohol functional group.

Now, let's explain why the other options are incorrect:

1. **Option 1 ($CH_{3}-O-CH_{3}$, dimethyl ether)**: Dimethyl ether lacks an O-H group, so it would not exhibit a strong band at $3300~cm^{-1}$. This makes it inconsistent with the given IR spectrum.

2. **Option 3 ($(CH_{2}OH)_{2}$, ethylene glycol)**: While ethylene glycol does have O-H groups, its molecular formula is $C_{2}H_{6}O_{2}$, not $C_{2}H_{6}O$. Therefore, it does not match the given molecular formula.

3. **Option 4 ($CH_{3}CHOH_{2}^{+}$, a protonated form of ethanol)**: This option represents a charged species, which is not typically considered in standard IR spectroscopy of neutral organic compounds. Additionally, the molecular formula does not match the given $C_{2}H_{6}O$.

In conclusion, Option 2 ($CH_{3}CH_{2}OH$, ethanol) is the correct answer as it aligns perfectly with the IR spectrum characteristics and the given molecular formula.