Your report will be based on aggregate data collected by students over several years. These data are listed below.

Before you compare these data with your own, please realize that there is considerable variability in what students report. One group will report that a compound is unreactive while another group will report that it reacts rapidly at room temperature. Therefore, I have "averaged" the data as I think best. The following ranks are plausible and agree with many student observations. Undoubtedly, a better designed experiment would yield more reliable results.

Also, because these data are open to question, I have not tried to sequence all of the compounds. Instead, I have grouped compounds that appear to display similar properties. Please treat all of the compounds in each group as having identical reactivity.

NaI in acetone

• Reacts @ 20C. 3-bromopropene, 1-bromobutane, 3-bromocyclohexene
• Reacts @ 40-50C. 1-bromo-2-methylpropane, bromomethylcyclohexane, 2-bromobutane, bromocyclopentane
• No reaction. 1-chlorobutane, 2-chlorobutane, 2-chloro-2-methylpropane, 1-bromopropene, bromobenzene, bromocycloheptane, bromocyclohexane, 2-bromo-2-methylpropane, 1-bromo-2,2-dimethylpropane

AgNO₃ in ethanol

• Reacts immediately @ 20C. 2-bromo-2-methylpropane, 3-bromocyclohexene
• Reacts quickly @ 20C. 2-chloro-2-methylpropane, bromocycloheptane, bromocyclopentane
• Reacts moderately @ 20C. 2-bromobutane, 3-bromopropene
• Reacts slowly @ 20C. 1-bromo-2-methylpropane, bromomethylcyclohexane, 1-bromo-2,2-dimethylpropane, bromocyclohexane
• Reacts @ 40-50C. 1-bromobutane, 2-chlorobutane
• No reaction. 1-chlorobutane, 1-bromopropene, 1-bromobenzene

Report

Due: Mon, Nov 17, 2008, 5 PM

The report for this experiment does not follow the usual format. Write answers to the questions listed below on a separate piece of paper (do not write your answers in your lab notebook). Don't forget to write your name, your lab day, and your box number at the top of your report. Your report should be no longer than two pages.

Describe three structure-reactivity trends that you see in the data. One should be associated with an SN2 mechanism. One should be associated with an SN1 mechanism. You can choose which mechanism you would like to discuss for the third trend.

In your descriptions: 1) identify the structural factor that seems to be responsible for the variation in reactivity, 2) identify at least three compounds of different reactivity that support your trend (identify more compounds if you can), 3) if possible, identify at least one compound that doesn't seem to obey the trend and, if possible, offer an explanation for its exceptional behavior.

Contest (optional)

On a 3x5 index card, write your name and a question about the SN1 or SN2 reactivity of these compounds that you would like me to answer. Bring the card to lab lecture (2008 students - Th, Nov 20) and I will have three of these cards drawn from a hat. The "winners" will receive my best thoughts regarding their questions and chocolate.