CHEM 2211 1nd Edition Lecture 28 Outline of Last Lecture I Sn2 reactions Outline of Current Lecture I Sn1 reactions Current Lecture Sn1 reactions Stands for substitution nucleophilic and 1 stands for unimolecular Unimolecular means only one molecule is used in the rate determining step This means the rate law only involves alkyl halides o Rate k alkyl halide This rate law is a first order reactant o Linearly dependent on the concentration of only one of the reactants Sn1 reactions only involve tertiary alkyl halides Most reactive o Tertiary alkyl halides Non reactive o Methyl alkyl halides o Primary alkyl halides o Secondary alkyl halides The tertiary alkyl halides can react in Sn1 reactions because unlike Sn2 reactions there are 2 steps before the product In Sn2 reactions everything happens at once the transition state has both the nucleophile and the leaving group where as in the transition state in Sn1 reactions first has the leaving group leave Then the nucleophile can come in with no steric hindrance Mechanism for Sn1 reactions These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Slow fast CH3 3C Br CH3 3C H2O CH3 3C O H CH3 3C OH H3O H Sn1 reactions of alkyl halides with asymmetric centers form 2 stereoisomers 1 has the same confirmation 2nd has the inverted confirmation o They are enantiomers Factors that affect the reactivity The type of alkyl halide Most reactive o RI o RBr o RCl o RF Least reactive Type of nucleophile Because the nucleophile does not take part in the rate determining state it does not have any affect
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