Lab 10: preparation of 2-chloro-2-methylbutane SN1 reaction

Purpose

perform a substitution reaction, forming an alkyl halide from a tertiary alcohol

SN1 reaction (favors cooler temps)

Reactant

2-methyl-2-butanol, is soluble in water

Product

 2-chloro-2-methylbutane, is insoluble in water

Alkyl halides

are organic molecules containing a halogen atom bonded to an sp3 hybridized carbon atom

Techniques in this lab:

Aqueous workup and separation of layers

Glass wares for Reaction/Distillation of alkenes:

5 mL conical vial, 3 mL conical vial, 10 mL graduated cylinder, centrifuge tube, 50 mL beaker, one small test tube, and 10 mL Erlenmeyer flask

Other Items needed for Alkenes reaction setup

Ring/clamp stand, hotplate/stir, and aluminum block

Silver nitrate test

used to determine if a tertiary alkyl halide was formed in this reaction

Bromine; Baeyer; permanganate test

chemical test could be used to determine if a competing elimination reaction occurred and a byproduct was formed in addition to your product

Correct Order for the Sn1 reaction

1.The alcohol is protonated by the hydrogen halide

2.The protonated alcohol loses a molecule of water

3.The carbocation is  attacked by the halide ion (X-)  

4.An alkyl halide is formed

intermediate

carbocation 3 most stable

starting material

tertiary alcohol

leaving group

water molecule

3 components are necessary for substitution rxn:

1. sp 3 hybridized carbon
2. Nucleophile
3. Leaving group

Sn1 rxns prefer substrates

bulky, tertiary alky substrate

how substitution works

nucleophilic weak conjugate base then adds to the carbocation
and substitution occurs

Low temperature

favors Sn1 reactions