Question

Experiment 14 SN2: Synthesis of 1-Bromobutane Alkyl halides can be prepared from their corresponding alcohols via an acid catalyzed substitution reaction. The mechanism of these acid catalyzed substitution reactions are labeled as SNI (substitution, nucleophilie, unimolecular) and S2 (substitution, nucleophilie, bimolecular). Tertiary alcohols follow the Syl route, primary alcohols follow the S2, route and secondary alcohols can follow either path. Sth CyHe 81 CH? Br-CH e-OH- -C-OH OH Figure / Conversion of 1-butanol into 1-bromobutane by an Sp2 mechanism The S2 reaction for converting 1-butanol to 1-bromobutane involves rapid protonation of the alcohol along with a concerted step where the nucleophile attacks the carbon, displacing water, The backside attack by the nucleophile is favored for primary substrates and less ideal for secondary and tertiary substrates. The product will be verified by gas chromatography by comparing the chromatograms of the starting material, 1-bromobutane standard, and your product. Confirmation of your product, 1-bromobutane can also be performed by reacting the product with a solution of sodium iodide in acetone. The primary alkyl halide will react by means of an S2 mechanism with the sodium iodide to form an insoluble precipitate. The appearance of a precipitate indicates a positive result suggesting the presence of a primary alkyl halide. OBJECTIVES In this experiment, you will • Synthesize 1-bromobutane via an S2 reaction. • Confirm the presence of a primary alkyl halide using the sodium iodide test. • Verify the product by gas chromatography, MATERIALS Part 1 Synthesis of 1-bromobutane 18 x 150 mm test tube two 250 mL beakers 10 ml graduated cylinder disposable Pasteur pipets and bulb heating mantle ring stand and utility clamp 1-butanol, reagent grade sodium bromide sulfuric acid, concentrated saturated sodium bicarbonate solution saturated sodium chloride solution sodium sulfate, anhydrous DI water ice sand boiling stone 5 ml glass vial and cap Organic Chemistry with Vernier Vernier Software & Technology 14 - 1

Answer 1

1 [Answer Answer 1. Answer 1o M OH + NaBr – & NaB. MB6t: NaOH tHE 2. Mechanism C3H5 MOH = ' sön the 21 BSCRIT I slow CHT MB B6 H "This is SN2 teachiom and 3N2 reach.com Proceeding through the transihic state (T. 5) T. Cathy Bromoçme 8th 7.3 Rate determining step: The attacks ols nucleophile (Bro) on leaving group containing carbon and displacement of leaving group at the same time is rate determing step of SNC mechanism. "Therefore rate of SN? reachecar proportional to the eccentraham ols nucleophile on d leaving group.