Chemistry Aldehydes & Ketones MDCAT 2017
PMDC Verified Question 65 of 94
In the reaction, "?" represents which one of the following products:

$$ \text{Primary Alcohol} \xrightarrow{\text{[O]} \ K_2Cr_2O_7 / H_2SO_4} \text{?} \xrightarrow{\text{[O]}} \text{Carboxylic Acid} $$
A
Ketone
B
Formic acid
C
Aldehyde
D
Ether
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Aldehyde
Concept:

The sequential oxidation of a primary alcohol involves a two-step pathway before fully converting to a carboxylic acid.

Solution:

  • A primary alcohol (\( R-CH_2OH \)) contains two oxidizable hydrogen atoms on the carbon bearing the hydroxyl group.


  • In the first oxidation step, these hydrogens are removed to form a carbonyl double bond at the terminal position, yielding an Aldehyde (\( R-CHO \)).


  • If oxidation continues, the highly reactive aldehyde bond is further oxidized by inserting an oxygen atom, producing a Carboxylic Acid (\( R-COOH \)).


Why other options are incorrect:

Ketones are formed by the oxidation of secondary alcohols. Formic acid is a specific final product (if starting from methanol), not the intermediate. Ethers are not oxidation products of alcohols.

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