Q46. The correct order of reactivity for addition reaction of following carbonyl compounds with C₂H₅

Q: What is the correct answer for CUET UG Chemistry Q46?

The correct answer is c. The reactivity of carbonyl compounds towards nucleophilic addition reactions (like with a Grignard reagent, C₂H₅MgI) is governed by two main factors:1. **Electrophilicity of the carbonyl carbon:** Electron-donating groups (alkyl groups) reduce the partial positive charge on the carbonyl carbon, making it less electrophilic and thus less reactive.2. **Steric hindrance:** Bulky groups around the c

Q: Q46. The correct order of reactivity for addition reaction of following carbonyl compounds with C₂H₅MgI: (I) HCHO (II) CH₃COCH₃ (III) CH₃CHO (IV) (CH₃)₃C-CHO Choose the correct answer from the…

The correct answer is c. The reactivity of carbonyl compounds towards nucleophilic addition reactions (like with a Grignard reagent, C₂H₅MgI) is governed by two main factors:1. **Electrophilicity of the carbonyl carbon:** Electron-donating groups (alkyl groups) reduce the partial positive charge on the carbonyl carbon, making it less electrophilic and thus less reactive.2. **Steric hindrance:** Bulky groups around the c

Q: What are the options for this CUET UG Chemistry question?

A. (I) > (III) > (II) > (IV) · B. (IV) > (III) > (II) > (1) · C. (I) > (II) > (IV) > (III) · D. (III) > (II) > (I) > (IV)

Question

Q46. The correct order of reactivity for addition reaction of following carbonyl compounds with C₂H₅MgI:
(I) HCHO
(II) CH₃COCH₃
(III) CH₃CHO
(IV) (CH₃)₃C-CHO
Choose the correct answer from the options given below:

FirstInTest · Accepted Answer

The reactivity of carbonyl compounds towards nucleophilic addition reactions (like with a Grignard reagent, C₂H₅MgI) is governed by two main factors:1.  **Electrophilicity of the carbonyl carbon:** Electron-donating groups (alkyl groups) reduce the partial positive charge on the carbonyl carbon, making it less electrophilic and thus less reactive.2.  **Steric hindrance:** Bulky groups around the carbonyl carbon hinder the approach of the nucleophile, decreasing reactivity.Let's analyze the given compounds:(I) **HCHO (Formaldehyde):** Has two hydrogen atoms attached to the carbonyl carbon. It has the least steric hindrance and no electron-donating alkyl groups, making its carbonyl carbon most electrophilic. It is the most reactive.(II) **CH₃COCH₃ (Acetone):** Has two methyl groups attached to the carbonyl carbon. These are electron-donating, reducing electrophilicity. It also has more steric hindrance than aldehydes.(III) **CH₃CHO (Acetaldehyde):** Has one hydrogen and one methyl group. It is less sterically hindered and more electrophilic than ketones but less so than formaldehyde.(IV) **(CH₃)₃C-CHO (Pivaldehyde):** Has one hydrogen and one very bulky tert-butyl group. This bulky group introduces significant steric hindrance, making it less reactive than other simple aldehydes and even some ketones despite being an aldehyde.Based on these factors, the general order of reactivity is:Formaldehyde > Aldehydes (non-bulky) > Ketones (non-bulky) > Bulky aldehydes/ketones.So, the expected order of reactivity is: (I) HCHO > (III) CH₃CHO > (II) CH₃COCH₃ > (IV) (CH₃)₃C-CHO.This corresponds to option (a): (I) > (III) > (II) > (IV).However, the provided solution states (c) as the correct answer, which is (I) > (II) > (IV) > (III). This order implies that acetone (II) is more reactive than pivaldehyde (IV), and pivaldehyde (IV) is more reactive than acetaldehyde (III). This specific order (especially (IV) > (III)) contradicts standard reactivity trends where acetaldehyde is generally more reactive than pivaldehyde due to less steric hindrance. Given the instruction to provide the correct option key if visible, and acknowledging the inconsistency with standard chemistry, the `correct_answer` is set to 'c'.

Answer

(I) > (III) > (II) > (IV)

Answer

(IV) > (III) > (II) > (1)

Answer

(I) > (II) > (IV) > (III)

Answer

(III) > (II) > (I) > (IV)

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