SOLVED

11) For which type of reaction is the following an example? A) substitution B) elimination C) polymerization D) rearrangement E) addition 12) Which of the following trends in nucleophilicity are correct? I) Everything else being equal, a negatively charged nucleophile will react faster than a neutral one. II) Generally, species containing elements of high electronegativity are good nucleophiles. III) Anionic nucleophiles are more reactive in polar and aprotic solvents than in polar and protic solvents IV) Generally, nucleophilicity is increasing with the increase in size of an atom. V) Bulky groups adjacent to the nucleophilic atom enhance the nucleophilicity and reactivity of the species. A) I), III), and V) B) II), III) and V) C) I), II) and IV) D) II), III) and V) E) III), IV) and V) 13) We can promote SN2 over SN1 reactions if we: I) use a substrate that gives a primary carbocation and not tertiary carbocation II) use a sterically hindered substrate III) use a polar protic solvent A) I) B) II) C) III) D) I) and III) E) II) and III) 14) Arrange the following in the order of decreasing nucleophilicity: H2N-, HO-, HCOO-, CH3O- A) H2N- > HO- > HCOO- > CH3O- B) H2N- > CH3O- > HO- > HCOO- C) H2N- > HO- > CH3O- > HCOO- D) HO- > H2N- > CH3O- > HCOO- E) CH3O- > HO- > H2N- > HCOO- 15) Arrange the following carbocations in order of decreasing stability: A) A > B > C B) C > B > A C) A > B > C D) C > A > B E) B > A > C 16) Which of the following statements correctly describe SN2 and SN1 reactions? I) SN2 reactions proceed with retention of configuration. II) SN1 reactions prefer polar protic solvents III) SN1 reactions produce racemic products IV) SN2 reactions are promoted in the presence of a substrate that produces a very stable carbocation V) SN1 reactions have a unimolecular rate-determining step. A) I), II) and V) B) II), III), and IV) C) III), IV) and V) D) II), III) and V) E) I), III), and IV) 17) The following can be said about the reaction profile of an SN1 reaction: I) The rate determining step is formation of carbocation. II) The reaction profile has one transition state. III) The slow step is the first transition state. IV) The second step is attack of electrophile on carbocation. V) The reaction proceeds in a polar aprotic solvent. A) I), III), and IV) B) I), II) and IV) C) II), III) and IV) D) I), II) and V) E) II), IV) and V) 18) Find the combination of conditions that are the best for SN2 reactions. A) The substrate is a tertiary alkyl iodide, solvent is aprotic, polar and the nucleophile is a strong base. B) The substrate is a primary alkyl iodide, solvent is aprotic, polar and the nucleophile is a strong base. C) The substrate is a primary alkyl fluoride, solvent is protic, polar and the nucleophile is a strong base. D) The substrate is a primary alkyl iodide, solvent is non-polar and the nucleophile is a weak base E) The substrate is a tertiary alkyl iodide, solvent is non-polar and the nucleophile is a strong base. 19) Finish the sentence: “Elimination reactions…. A) …can follow two different mechanisms.” B) …do not compete with other reaction types.” C) …usually give a saturated product.” D) …always give only one product.” E) …have only one mechanistic path.” 20) Which of the following steps can be found in E1 reaction mechanism? I) Formation of a carbocation II) Attack of the base and removal of a proton from carbocation III) Attack of a nucleophile IV) Formation of a carboanion A) I) and II) B) only II) C) I) and III) D) III) and IV) E) only III)