Reactive intermediates: carbocations, carbanions, free radicals, carbenes and nitrenes - Question Bank
1. Which reactive intermediate has a pyramidal geometry at the central carbon atom?
2. The Kolbe electrolysis of carboxylic acids produces:
3. Which reactive intermediate is characterized by a carbon atom with a lone pair and two bonds?
4. Which of the following is a resonance-stabilized carbocation?
5. The Tiffeneau-Demjanov rearrangement is a type of:
6. Which statement about triplet carbenes is correct?
7. The nucleophilic addition to carbonyl compounds often involves the formation of:
8. Which intermediate is planar and has an empty p orbital?
9. The Hunt-Shorter rearrangement is a type of:
10. Which reaction involves the generation of a free radical from an azo compound?
11. The stability of a carbanion is increased by:
12. Which of the following is an example of a tertiary carbocation?
13. The Fischer indole synthesis involves the cyclization of a phenylhydrazone, which can be thought of as involving:
14. In organic synthesis, which intermediate is often generated using organometallic reagents?
15. The insertion reactions of carbenes into C-H bonds are characteristic of:
16. Which of the following is a resonance-stabilized carbanion?
17. The stability order of free radicals is generally similar to that of:
18. Which reactive intermediate is involved in the Wurtz reaction?
19. The Schmidt reaction involves the reaction of a ketone or aldehyde with:
20. A carbene with two identical substituents on the carbon atom is called:
21. The term 'radical scavenger' refers to a substance that:
22. The carbon atom in a carbanion is typically hybridized:
23. Which reagent is commonly used to generate free radicals from peroxides?
24. The stability of carbanions decreases with the introduction of:
25. Which of the following is an electrophile?
26. The Wolff rearrangement converts an alpha-diazoketone into:
27. Dichlorocarbene (:CCl2) is an example of:
28. The addition of halogens to alkenes often proceeds via a:
29. Which of the following is a strong nucleophile and a strong base?
30. Which carbocation is least stable?
31. The Hofmann rearrangement is initiated by the formation of:
32. The geometry around the carbon atom in a carbene is typically:
33. Which of the following would most readily undergo homolytic cleavage?
34. The negative charge in a carbanion is localized on:
35. Which statement about carbocations is FALSE?
36. The Curtius rearrangement involves the formation of which reactive intermediate?
37. Which of the following is a triplet carbene?
38. The stability of carbanions follows the order:
39. Which species is resonance stabilized?
40. The hybridization of the carbon atom in a methyl carbocation (CH3+) is:
41. Which of the following is a common method for generating free radicals?
42. Singlet carbenes have their two non-bonding electrons in:
43. Homolytic cleavage of a covalent bond leads to the formation of:
44. Which of the following is an example of a carbanion?
45. The stability order of carbocations from least to most stable is:
46. Nitrenes are the nitrogen analogues of:
47. Carbenes are neutral molecules with a carbon atom having:
48. Free radicals are characterized by the presence of:
49. Carbanions are typically formed by the abstraction of which type of hydrogen atom?
50. Which of the following is the most stable carbocation?