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Chapter 7 
Alkyl Halides: Nucleophilic Substitution and 
Elimination Reactions 
 
Review of Concepts 
Fill in the blanks below. To verify that your answers are correct, look in your textbook at the end of Chapter 7. 
Each of the sentences below appears verbatim in the section entitled Review of Concepts and Vocabulary. 
 
 Good leaving groups are the conjugate bases of __________ acids. 
 SN2 reactions proceed via ______________ of configuration, because the nucleophile can only 
attack from the back side. 
 SN2 reactions cannot be performed with ___________ alkyl halides. 
 ________________ solvents contain a hydrogen atom connected directly to an electronegative 
atom, while _________________ solvents lack such a hydrogen atom. A ________________ 
solvent will speed up the rate of an SN2 process by many orders of magnitude. 
 In the laboratory, methylation is accomplished via an SN2 process using methyl iodide. In 
biological systems, the methylating agent is called __________________________. 
 A trans  bond cannot be incorporated into a small ring. When applied to bicyclic systems, this 
rule is called ___________ rule, which states that it is not possible for a _____________ carbon of 
a bicyclic system to possess a C=C double bond if it involves a trans  bond being incorporated in 
a small ring. 
 E2 reactions are regioselective and generally favor the more substituted alkene, called the 
___________ product. 
 When both the substrate and the base are sterically hindered, an E2 reaction can favor the less 
substituted alkene, called the _____________ product. 
 If the  position has two different protons, the resulting E2 reaction can be stereoselective, because 
the ________ isomer will be favored. 
 If the  position has only one proton, an E2 reaction is said to be _________________, because the 
proton and the leaving group must be ______________ to one another. 
 Unimolecular nucleophilic substitution reactions are called ______ reactions. An SN1 mechanism 
is comprised of two core steps: 1) ________________________ to give a carbocation 
intermediate, and 2) _____________________________. 
 When a solvent molecule functions as the attacking nucleophile, the resulting SN1 process is called 
a ___________________. 
 Unimolecular elimination reactions are called _____ reactions. 
 SN1 processes are favored by __________________ solvents. 
 SN1 and E1 processes are observed for tertiary alkyl halides, as well as allylic and _____________ 
halides. 
 When the  position is a chiral center, an SN1 reaction gives nearly a racemic mixture. In practice, 
there is generally a slight preference for _______________ of configuration, as a result of the 
effect of ion pairs. 
 If a CH bond is being broken in the rate-determining step, then a ___________ isotope effect is 
observed. If, however, the C-H bond is broken during a step that is not rate-determining, then any 
measureable effect is said to be a _______________ isotope effect. 
 Substitution and elimination reactions often compete with each other. To predict the products, 
three steps are required: 1) determine the function of the _____________, and 2) analyze the 
____________ and determine the expected mechanism(s), and 3) consider any relevant 
regiochemical and stereochemical requirements. 
 Alcohols react with HBr to give alkyl halides, either via an _____ pathway (for primary and 
secondary substrates) or via an _____ pathway (for tertiary substrates). 
 When treated with concentrated sulfuric acid, tertiary alcohols are converted into _________ via 
an E1 process. 
 A ______________ analysis shows the product first, followed by reagents that can be used to 
make that product. 
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