Question

How can we distinguish the following compounds from each other?

`A)` `"CCl"_4` and `"C"_4"H"_10`
`B)` 1-propanol and 2-methylpropan-2-ol
`C)` pentanamine and pentane
`D)` pent-1-ene and benzene

Answer 1

A) `" "C Cl_4` and `C_4H_10`

Tetrachloromethane or Carbon tetra chloride (`C Cl_4)`has molar mass `154g"/"mol` whereas butane `C_4H_10` has molar mass 58 `g"/"mol`. So due to higher inter molecular force the first one is liquid at normal temperature and pressure whereas the second one is a gas under the same condition. The second is highly inflammable gas and commonly used as a gaseous fuel. The carbon in (`C Cl_4)` is in its highest oxidation state (+4) as in `CO_2`. So this compound is not at all inflammable , it is used as good fire extinguisher (trade name- pyrene )

So testing only the inflammability they can easily be distinguished

B) 1-propanonl(`CH_3CH_3CH_2OH->` pimary alcohol) and

2-methylpropan-2-ol (`CH_3)_3COH->`tertiary alcohol)

Lucas' reagent is a solution of anhydrous zinc chloride in concentrated hydrochloric acid. This is used to distinguish between primary,secondary and tertiary alcohol of lower molar masses.

They all produce alkyl halides when treated with this reagent through `SN_1` mechanism and the alkyl halides formed being insoluble in the reaction mixture it makes the mixture turbid

In case of 2-methylpropan-2-ol the turbidity appears almost immediately but in case of 1-propanonl turbidity appears after long time.

C) Pentanamine `(C_5H_11NH_2)->` primary amine

It is soluble in dilute `HCl` and it responds to carbylamine reaction.

and pentane `(C_5H_12)->` alkane

It is insoluble in dilute `HCl` and it does not respond to carbylamine reaction.

In carbileamine test the comound under test is treated with chloform and alcoholic `KOH`. the formation of carbile amine is detected by its foul smell.

Reaction

D). Pent-1-ene `(CH_3CH_2CH_2CH=CH_2)->`alkene

and benzene `(C_6H_6)->`aromatic.

Both the compounds are unsaturated but the second one being aromatic one it is more stable and does not respond to test of un-saturation like dicolorization of red bromine water as done by the first one.

Reaction