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Benzaldehyde and formaldehyde do not und...

Benzaldehyde and formaldehyde do not undergo condensation on treatment with NaOH whereas acetaldehyde does. Why?

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Aldol condensation requires the presence of a-hydrogen atom to give a carbanion > C-CHO. Benzaldehyde and formaldehyde do not contain any a-hydrogen, and hence donot undergo aldol condensation and only give Cannizzaro.s reaction products. Acetaldehyde due to the presence of `alpha`-hydrogen atoms, undergoes aldol condensation.
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ICSE-ALDEHYDES, KETONES AND CARBOXYLIC ACIDS-EXERCISE (PART-II DESCRIPTIVE QUESTIONS) (VERY SHORT QUESTIONS)
  1. Why ketones do not easily unergo oxidation?

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  2. Ethanal undergoes aldol condensation but trichloroethanal does not.

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  3. Benzaldehyde and formaldehyde do not undergo condensation on treatment...

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  4. How will you distinguish between acetone and ethyl alcohol?

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  5. Which of the following compounds is used in the preservation of biolog...

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  6. What are the following: Fehling's solution

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  7. What are the following: Tollens' reagent

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  8. What are the following: Baeyer's reagent

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  9. What are the following: Baeyer's reagent

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  10. Write the chemical name and structure of Rochelle salt.

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  11. What type of reactions are given by the carbonyl group in aldehydes an...

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  12. Name two methods commonly used to convert a carbonyl (gtC=O) group int...

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  13. What type of aldehydes and ketones undergo aldol condensation?

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  14. What type of aldehydes undergo Cannizzaro's reaction?

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  15. Which ketones undergo iodoform test?

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  16. Name the aldehyde which does not give Fehling solution test.

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  17. Name one reagent used to convert toluene into benzaldehyde.

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  18. Give the chemical reaction, when ethanal is heated with HI.

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  19. Mention an industrial product manufactured from methanol.

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  20. How will you test aldehydes and ketones with: Tollens' reagent

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