Which one of the following reactions will not result in the formation of carbon-carbon bond?

To determine which reaction does not result in the formation of a carbon-carbon bond, we need to analyze each option step by step. Let's recall the key features of each reaction.

Starting with option A: Friedel Craft's acylation. This reaction involves an aromatic compound reacting with an acyl chloride (R-COCl) in the presence of a Lewis acid catalyst like AlCl₃. The acyl group attaches to the aromatic ring, forming a new bond between the carbonyl carbon of the acyl group and a carbon atom of the aromatic ring. For example, benzene reacts with acetyl chloride to form acetophenone: $$C_{6}H_{6} + CH_{3}COCl \xrightarrow{\text{AlCl}_3} C_6H_5COCH_3$$ Here, a new carbon-carbon bond is formed between the benzene ring carbon and the carbonyl carbon of the acetyl group. Thus, this reaction does form a carbon-carbon bond.

Next, option B: Reimer-Tieman reaction. This reaction is used for ortho-formylation of phenols. Phenol reacts with chloroform (CHCl₃) in the presence of a strong base like NaOH to produce salicylaldehyde (2-hydroxybenzaldehyde). The mechanism involves the formation of dichlorocarbene (:CCl₂), which attacks the ortho position of the phenoxide ion. This results in a new bond between the carbon of the benzene ring and the carbon of the formyl group. The reaction is: $$C_{6}H_{5}OH + CHCl_{3} + NaOH -\gt o-HOC_{6}H_{4}CHO$$ A carbon-carbon bond is formed between the aromatic carbon and the carbon of the -CHO group. Therefore, this reaction also forms a carbon-carbon bond.

Now, option C: Cannizaro reaction. This is a disproportionation reaction that occurs with aldehydes lacking an alpha hydrogen, such as formaldehyde or benzaldehyde. In this reaction, one molecule of aldehyde is oxidized to a carboxylic acid, while another molecule is reduced to an alcohol. For example, formaldehyde undergoes the Cannizaro reaction: $$2HCHO -\gt [\text{NaOH] HCOONa + CH3OH}$$ The mechanism involves a hydride ion transfer from one aldehyde molecule to another. There is no formation of a new carbon-carbon bond; instead, bonds are rearranged to form C-O bonds in the carboxylate and alcohol. The carbon atoms remain separate—no coupling occurs. Hence, this reaction does not form a carbon-carbon bond.

Finally, option D: Wurtz reaction. This reaction couples two alkyl halides using sodium metal in dry ether solvent. For instance, two molecules of bromoethane react to form butane: $$2CH_{3}CH_{2}Br + 2Na -\gt CH_{3}CH_{2}CH_{2}CH_{3} + 2NaBr$$ Here, the alkyl groups from the halides combine, forming a new carbon-carbon bond between the two carbon atoms. Thus, this reaction clearly forms a carbon-carbon bond.

In summary:

• Friedel Craft's acylation (A) forms a carbon-carbon bond.
• Reimer-Tieman reaction (B) forms a carbon-carbon bond.
• Cannizaro reaction (C) does not form a carbon-carbon bond.
• Wurtz reaction (D) forms a carbon-carbon bond.

Hence, the correct answer is Option C.