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Unformatted text preview: Riti Gupta Chem 3AL Section 112 Lab Partner: Lauren Thomas Experiment 10 : Nucleophilic Substitution Reactions of Alkyl Halides Discussion : The NaI/acetone reagents established S N 2 reaction conditions, as NaI is a strong nucleophile whereas the AgNO 3 /Ethanol reagents established S N 1 reaction conditions, as the ethanol solvent acted like a weak nucleophile during solvolysis. 1-bromopentane, a primary halide with Br as a good leaving group, reacted with NaI in acetone at room temperature, as predicted, since primary halides are ideal for undergoing S N 2 reactions, due to the lack of steric hindrance by substituents that the nucleophile must face when attacking the molecule and do not need extra heat to catalyze the reaction. Contrary to predictions, 1-bromopentane also reacted in AgNO 3 /ethanol, even though primary halides are not suitable for S N 1 reactions due to the high energy and low stability of the primary carbocation involved in transition state. In this case, because bromine is a good leaving group, the carbocation was able to form while being catalyzed with the extra heat from the 50°C water bath. Surprisingly, 1-chloropentane did not react with NaI at room temperature or in the heat bath, but it did react with ethanol in the heat bath. Both 2-bromopentane and 3-bromopentane are secondary halides, and thus were able to react with both the NaI and the ethanol, as secondary halides have small amounts of steric hindrance and form fairly stable carbocations. 3-bromopentane required to be heated in the Sform fairly stable carbocations....
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