Which procedures can be used to distinguish between the given two compounds?

All of them 

The correct answer is option 4. All of them.

Out of the given options, all three procedures can be used to distinguish between butanol (1-butanol) and 2-butanol (2-butanol):

Lucas reagent test: This is the most commonly used method for differentiating between primary, secondary, and tertiary alcohols. Lucas reagent is a solution of zinc chloride (ZnCl₂) in concentrated hydrochloric acid (HCl).

Observation: Primary alcohols (like butanol) react with Lucas reagent to form a white, cloudy precipitate within a short time (a few minutes). Secondary alcohols (like 2-butanol) react more slowly, forming a turbidity or cloudiness after a longer period (up to 15 minutes). Tertiary alcohols do not react with Lucas reagent.

Victor Meyer test: This test determines the molecular weight of a compound by measuring its boiling point elevation. However, it's less commonly used for differentiating isomers like butanol and 2-butanol.

Iodine in sodium hydroxide (I₂/NaOH) test: This test is specific for primary alcohols. Primary alcohols react with I₂/NaOH to produce a yellow precipitate of iodoform (CHI₃). Secondary and tertiary alcohols do not react with this reagent in this way.

Explanation of why each method works:

Lucas reagent test: The different reactivities of alcohols with Lucas reagent arise from the varying ease of forming carbocations. Primary alcohols are more readily converted to carbocations compared to secondary alcohols due to the stability of the resulting primary carbocation. This faster reaction with Lucas reagent leads to the observed difference in precipitate formation time.

Victor Meyer test: While not as specific for differentiating these isomers, the slight difference in molecular weight between butanol (74.12 g/mol) and 2-butanol (74.12 g/mol) can be reflected in their boiling point elevations. However, the difference might be small and require precise measurements.

I₂/NaOH test: This test relies on the oxidation of the primary alcohol to an aldehyde by the basic I₂/NaOH solution, followed by the further oxidation of the aldehyde to iodoform. Since 2-butanol is a secondary alcohol, it doesn't undergo this specific reaction pathway and doesn't produce iodoform.

Therefore, all three procedures can be employed for distinguishing between butanol and 2-butanol, with Lucas reagent being the most convenient and specific method for this purpose.