The ring systems having following characteristics are aromatic.
(i) Planar ring containing conjugated $\pi$ bonds.
(ii) Complete delocalisation of the $\pi$-electrons in ring system i.e., each atom in the ring has unhybridised $p$-orbital, and
(iii) Presence of $(4 n+2) \pi$ - electrons in the ring where $n$ is an integer $(n=0,1,2, \ldots \ldots \ldots)[$ Huckel rule]. Using this information classify the following compounds as aromatic/non-aromatic.
| Compound | Planaring | Complete delocalisation of $$\pi$$-electron | Huckel rule $$(4n+2)\pi$$ electron | Aromatic or non-aromatic | |
|---|---|---|---|---|---|
| A. |  |
P | P | $$ 6 \pi e^{-} $$ Huckel rule obeyed |
Aromatic |
| B. |  |
I | I Incomplete (sp$$^3$$ hybrid carbon) | $$6\pi e^-$$ | Non-aromatic |
| C. |  |
P | P | $6 \pi e^{-}(4 n+2+$ lone pair $e^{-}$) Huckel rule verified | Aromatic |
| D. |  |
P | I | $4 \pi e^{-}$ | Anti-aromatic |
| E. |  |
P | P | Huckel rule obeyed | Aromatic |
| F. |  |
P | P | $2 \pi e^{-}$Huckel rule verified $n=0$ | Aromatic |
| G. |  |
P | I | $8 \pi e^{-}$Huckel rule not verified | Non-aromatic |
Which of the following compounds are aromatic according to Huckel's rule?
A. The compound has $8 \pi$ electrons. It will be non-aromatic. Both rings are non-benzenoid.
B. The compound is aromatic. It has $6 \pi e^{-}$delocalised electron $\left(4 \pi e^{-}+2\right.$ lone pair electrons), all the four carbon atoms and the N atom are $s p^2$ hybridised.
C. The compound contains $6 \pi$ electrons but not in the ring hence it is non-aromatic.
D. $10 \pi e^{-}$obeying Huckel rule and the ring is planar. It is aromatic.
E. In this compound one six membered planar ring has $6 \pi e^{-}$although it has $8 \pi$ electrons in two rings. It is therefore aromatic.
F. It has $14 \pi$ electrons in conjugation and in the planar ring, Huckel rule is verified. It will be aromatic.
Suggest a route to prepare ethyl hydrogensulphate $\left(\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OSO}_2-\mathrm{OH}\right)$ starting from ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$.
For preparation of ethyl hydrogensulphate $\left(\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OSO}_2-\mathrm{OH}\right)$ starting from ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$, it is the two steps mechanism.
Step I Protonation of alcohol
Step II Attack of nucleophile
Temperature should not be allowed to rise above 383 K , otherwise diethyl ether will be produced at 413 K or ethene at 433 K .
Match the reagent from Column I which on reaction with $\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}_2$ gives some product given in Column II as per the codes given below
| Column I | Column II | ||
|---|---|---|---|
| A. | $\mathrm{O}_3 / \mathrm{Zn}+\mathrm{H}_2 \mathrm{O}$ | 1. | Acetic acid and $\mathrm{CO}_2$ |
| B. | $\mathrm{KMnO}_4 / \mathrm{H}^{+}$ | 2. | Propan-1-ol |
| C. | $\mathrm{KMnO}_4 / \mathrm{OH}^{-}$ | 3. | Propan-2-ol |
| D. | $\mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}$ | 4. | Acetaldehyde and formaldehyde |
| E. | $\mathrm{B}_2 \mathrm{H}_6 / \mathrm{NaOH}^{+}$and $\mathrm{H}_2 \mathrm{O}_2$ | 5. | Propane-1, 2-diol |
A. $\rightarrow$ (4)
B. $\rightarrow$ (1)
C. $\rightarrow$ (5)
D. $\rightarrow(3)$
E. $\rightarrow(2)$
| Column I | Column II | ||
|---|---|---|---|
| A. | $\mathrm{O}_3 / \mathrm{Zn}+\mathrm{H}_2 \mathrm{O}$ | 1. |  |
| B. | $\mathrm{KMnO}_4 / \mathrm{H}^{+}$ | 2. | $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}_2 \xrightarrow[\mathrm{H}^{+}]{\mathrm{KMnO}_4} \underset{\text { Aceticacid }}{\mathrm{CH}_3 \mathrm{COOH}}+\mathrm{CO}_2$ |
| C. | $\mathrm{KMnO}_4 / \mathrm{OH}^{-}$ | 3. |  |
| D. | $\mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}$ | 4. | $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CH}_2 \xrightarrow[\text { (Markn addition) }]{\mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}} \underset{\text { Propan-2-ol }}{\mathrm{CH}_3-\mathrm{CH}(\mathrm{OH})-\mathrm{CH}_3}$ |
| E. | $\mathrm{B}_2 \mathrm{H}_6 / \mathrm{NaOH}^{+}$and $\mathrm{H}_2 \mathrm{O}_2$ | 5. |  |
Match the hydrocarbons in Column I with the boiling points given in Column II.
| Column I | Column II | ||
|---|---|---|---|
| A. | n-pentane | 1. | 282.5 K |
| B. | iso-pentane | 2. | 309 K |
| C. | neo-pentane | 3. | 301 K |
A - (2), B - (3), C - (1)
| Column I | Column II | ||
|---|---|---|---|
| A. | n-pentane | 1. | 309 K due to no branch |
| B. | iso-pentane | 2. | 301 K due to one branch |
| C. | neo-pentane | 3. | 282.5 K due to two branches |