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In HS^(-), I^(-), R-NH(2), NH(3) order o...

In `HS^(-)`, `I^(-)`, `R-NH_(2)`, `NH_(3)` order of proton accepting tendency will be

A

`I- gt NH_3 gt R-NH_2 gt HS^-`

B

`NH_3 gt R-NH_3 gt HS^(-) gt I^-`

C

`RNH_2 gt NH_3 gt HS^- gt I^-`

D

`HS^(-) gt RNH_2 gt NH_3 gt I^-`

Text Solution

AI Generated Solution

The correct Answer is:
To determine the order of proton-accepting tendency (basicity) of the species HS^(-), I^(-), R-NH2, and NH3, we can analyze each species based on their ability to donate a lone pair of electrons to a proton (H^+). ### Step-by-Step Solution: 1. **Identify the Species**: We have four species to consider: HS^(-), I^(-), R-NH2, and NH3. 2. **Understand Basicity**: Basicity is the ability of a species to accept protons. The more basic a compound is, the greater its tendency to accept a proton. 3. **Analyze R-NH2**: - R-NH2 has a nitrogen atom with a lone pair of electrons. - The presence of the alkyl group (R) increases the electron density on nitrogen due to the +I (inductive) effect, making it more basic. 4. **Analyze NH3**: - NH3 also has a lone pair on nitrogen, but it lacks the electron-donating effect of an alkyl group. - Therefore, NH3 is less basic than R-NH2. 5. **Analyze HS^(-)**: - HS^(-) has a lone pair of electrons on sulfur. - While it can accept protons, the basicity is affected by the electronegativity of sulfur and the presence of the negative charge, making it less basic than R-NH2 and NH3. 6. **Analyze I^(-)**: - I^(-) has a lone pair of electrons, but iodine is a larger atom with a significant amount of electron delocalization due to its vacant orbitals. - This delocalization reduces the electron density available for proton acceptance, making I^(-) the least basic of the four species. 7. **Order the Species**: Based on the analysis: - R-NH2 is the most basic due to the +I effect enhancing electron density. - NH3 is next, as it has a lone pair but lacks additional electron density. - HS^(-) follows, as it can accept protons but is less basic than NH3. - I^(-) is the least basic due to electron delocalization. Thus, the order of proton-accepting tendency (basicity) is: **R-NH2 > NH3 > HS^(-) > I^(-)** ### Final Answer: The order of proton-accepting tendency will be: **R-NH2 > NH3 > HS^(-) > I^(-)**.
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