CHEM 241 ALCOHOLS AND ALKYL HALIDES CHAP 5 ASSIGN

Transcription

1 CEM 241 ALCOOLS AND ALKYL ALIDES CAP 5 ASSIGN 1. What is the IUPAC name of the compound below? A. 3-isobutyl-2-hexanol B. 2-methyl-5-propyl-6-heptanol C. 2-methyl-5-(1-hydroxyethyl)octane D. 6-methyl-3-propyl-2-heptanol 2. What is the IUPAC name of the compound below? A. 8-chloro-4-isopropyl-4,7-dimethylnonane B. 2-chloro-6-isopropyl-3,6-dimethylnonane C. 2-chloro-3,6,7-trimethyl-6-propyloctane D. 6-sec-butyl-2-chloro-3,6-dimethyloctane 3. What is the IUPAC name of the following compound? A. cis-3-methylcyclohexanol B. trans-3-methylcyclohexanol C. cis-5-methylcyclohexanol D. trans-5-methylcyclohexanol 4. Identify the tertiary halide(s). A. I and II B. II and III C. III and IV D. only IV 5. The product of free-radical halogenation reactions is an alkyl halide. The major amount of this halide forms during the second step of propagation. owever, you should be aware that one possible termination step also forms alkyl halides. Why does the majority of the alkyl halide product come from the propagation step and not the termination step? A. At any given time during the reaction, the concentration of both the alkyl radical and the halide radical is high enough that they can readily come together to form alkyl halides during propagation. B. At any given time during the reaction, the concentration of both the alkyl radical and the halide radical is so low that the chance of each of them finding the other to form alkyl halides during a termination step is very small. C. The initiation step converts 100% of the halogen to halide radicals through a light- or heat-induced homolytic bond cleavage. This step ensures that there is always a high concentration of halide radical present for reactivity in a propagation step. D. The second step of propagation (combination of an alkyl radical with a halide radical) is highly endothermic and therefore takes place very rapidly. E. Once the alkyl halide forms during a termination step, the carbon-halogen bond is broken in a homolytic fashion and the newly generated carbon radical goes back into a propagation step for further reactivity. 1 P a g e

2 6. The most stable conformation for 1,2-ethanediol (ethylene glycol) is shown below. It is the most stable conformation because: A. this corresponds to an anti conformation. B. in general, gauche conformations possess the minimum energy. C. it is stabilized by intramolecular hydrogen bonding. D. it is a staggered conformation. E. it has the highest energy of all the possibilities. 7. Predict the major product of the following reaction. O O A. B. C. D. E. The reaction does not take place. 8. Which of the following are the chain propagating steps in the free radical chlorination of methane? A. I and III B. II and VI C. III and IV D. III and V 9. Which of the following is not a chain termination step in free-radical halogenation? A. B. C. D. E. 10. Why is it that iodine does not do free-radical halogenations? A. Light cannot homolytically cleave the I I bond as it does for Br 2 and Cl 2. B. The iodine radical is too unreactive to abstract hydrogen atoms from even tertiary carbons. C. Carbon radicals will not abstract an iodine atom from I 2. D. Iodine is far too reactive and typically explodes in the presence of organic compounds. E. Iodine atoms recombine faster than the other halogens and thus terminate the reaction too rapidly. 2 P a g e

3 11. What is the major product of the following reaction? A. B. C. D. E. 12. Consider the following tertiary carbon radical. What orbital does the radical (single unpaired electron) occupy? A. s orbital B. p orbital C. sp 3 orbital D. sp 2 orbital E. sp orbital 13. When we use the word "mechanism" in describing a chemical reaction, what does this word refer to? A. A mechanism provides insight into electron movement and bonding that takes place during a chemical transformation. B. A mechanism provides a useful means of predicting the product(s) of chemical reactions. C. A mechanism provides unequivocal proof of the given pathway (in terms of electron movement and bonding) that a reaction follows. D. Both A and B are correct. E. Both B and C are correct. 14. Which of the following molecules would not be a product of one of the propagation steps involved in free-radical halogenation? A. B. C. D. E. 15. Which method or methods would work to quantitatively prepare a sodium ethoxide solution? I. C 3C 2O + NaO II. C 3C 2O + Na III. C 3C 2O + Na A. I and II B. I and III C. II and III D. I, II, and III 16. Which halogen forms the weakest bond to carbon? A. F B. Cl C. Br D. I 17. ow many C 3 6Cl 2 constitutional isomers do you expect in the dichlorination of propane? A. two B. three C. four D. five 3 P a g e

4 18. Predict the major product of the following reaction. A. B. C. D. E. 19. Arrange the following alcohols in order of their decreasing reactivity with Br (most reactive first). A. I > II > III B. I > III > II C. III > I > II D. II > III > I 20. Chlorination of pentane gives a mixture of isomers having the molecular formula C 5 11Cl. The percentage of 1-chloropentane is 22%. Assuming the secondary hydrogens in pentane are equally reactive to monochlorination, what is the percentage of 3-chloropentane in the mixture? Work must be shown to receive credit. 21. What are the products of the following reaction? A. 1-bromobutane and water B. 1-bromobutane and hydrogen C. butane and OBr D. C 3C 2C 2C 2OBr + hydrogen 22. Which of the following is not a good method to make bromocyclopentane? A. cyclopentanol plus Br B. cyclopentanol plus NaBr C. cyclopentanol plus PBr 3 D. cyclopentane plus Br 2 with light E. SOBr Which constitutional isomer of C 6 14 gives only two monochlorination products? A. 2-methylpentane B. 2,2-dimethylbutane C. 3-methylpentane D. 2,3-dimethylbutane 24. What is the nucleophile in the following substitution reaction? A. (C 3) 3CO B. (C 3) 3C + C. Br D. + 4 P a g e

5 25. Calculate of reaction for the free radical bromination of cyclopentane to give bromocyclopentane. Work must be shown to receive credit. 26. On the basis of your knowledge of the reaction of halogens with alkanes, decide which product you would not expect to be formed in even small quantities in the bromination of ethane? A. BrC 2C 2Br B. C 3C 2C 2C 3 C. C 3CBr 2 D. C 3C 2C 2Br E. BrC 2C 2C 2C 2Br 27. Consider the result of a free-radical halogenation of an alkane, using the interhalogen compound Br Cl. On the basis of what you know of the mechanism of this type of halogenation, decide which of the following statements would be true of the process? (Assume that Br Cl cannot disproportionate to Br 2 and Cl 2 under the reaction conditions.) A. alogenation would occur and create a carbon-chlorine bond with the selectivity typically observed for chlorination. B. alogenation would occur and create a carbon-chlorine bond with the selectivity typically observed for bromination. C. alogenation would occur to create a carbon-bromine bond with the selectivity typically observed for chlorination. D. alogenation would occur to create a carbon-bromine bond with the selectivity typically observed for bromination. E. Roughly equal amounts of bromination and chlorination would occur, with a selectivity intermediate between the two. 28. If you wanted to get the best yield of compound B from compound A, you would: A. use chlorine + light rather than bromine + light B. use bromine + light rather than chlorine + light C. neither would give >50% yield D. either would give >50% yield compound A? X compound B NAME DATE ANSWER SEET CEM 242 CAP 5 ASSIGN FALL P a g e