Incorrect method of preparation for alcohols from the following is:

We need to identify which method does NOT correctly prepare alcohols.

Option 1:

This is a correct method. Grignard reagents ($$RMgBr$$) are powerful nucleophiles that attack the carbonyl group of ketones. The mechanism involves nucleophilic addition of $$R^-$$ to the electrophilic carbonyl carbon, forming an alkoxide intermediate. Subsequent hydrolysis (treatment with dilute acid) gives a tertiary alcohol:

This is one of the most important methods for synthesizing alcohols.

Option 2:

This is a correct method. The hydroxide ion ($$OH^-$$) acts as a nucleophile and attacks the carbon bearing the halogen in an $$S_N2$$ (or $$S_N1$$) reaction, displacing the halide ion:

This nucleophilic substitution reaction produces an alcohol.

Option 3:

This is a correct method. In this two-step process, the alkene first reacts with borane ($$BH_3$$) to form a trialkylborane (hydroboration), which is then oxidized with alkaline hydrogen peroxide ($$H_2O_2/NaOH$$) to give an alcohol. The reaction gives anti-Markovnikov addition and syn-addition of water across the double bond:

Option 4:

This is an INCORRECT method for preparing alcohols. Ozonolysis involves treating an alkene with ozone ($$O_3$$) followed by a reductive workup (using $$Zn/H_2O$$ or $$(CH_3)_2S$$). This reaction cleaves the carbon-carbon double bond and produces aldehydes and/or ketones, NOT alcohols:

The products are carbonyl compounds (aldehydes or ketones depending on the substitution), not hydroxyl compounds.

The correct answer is Option 4: Ozonolysis of alkene is an incorrect method for preparing alcohols.