Preparation and Reactivity of Sn1 2-Bromobutane

Preparation and SN1 Reactivity of 2-Bromobutane Paul DeJong De graphemement of Chemistry, Illinois State University, Normal, IL 61790-4160 Submitted April 4, 2013 Introduction The settle of part 1 of the lab is to prepare 2-Bromobutane using SN1 reactions. The purpose of part 2 of the lab is to consider the relative reactivity of alkyl halides under SN1 conditions. Results and Discussion The Overall Reaction The Proposed Mechanism Experimental function To prepare 2-bromobutane in part one of the lab, you have to set up a flask mechanism with a thermowell and a Claisen adapter.Attached to the Claisen adapter is a thermometer measuring the temperature in the flask and a vertical condenser for reflux. Add in the reactants to the flask, sulfuric acid, 2-butanol, and ammonium bromide. Heat to 95OC and then maintain temperature for 30 minutes. Then, water was added and simple(a) distillation began. The aqueous layer of the distillate was removed leaving the product, 2-bromobutane. Fo r part 2, two drops of each of the next were placed in 3 different test tubes 2-bromobutane, 1-bromoutane and 2-bromo-2-methylpropane.In each of the tubes an even amount of silver treat is added. Observations of the reactions precipitate are recorded. Same process is done with 2-chlorobutane, 2-iodobutane, and 2-bromobutane. Experimental Stoichiometry fuse Molecularweight Quantity Moles 2-butanol 74. 12 g 7. 4 mL (6. 0 g) 0. 081 Sulfuric acid 98. 08 g 20 mL (12M) 0. 24 ammonium ion bromide 97. 94 g 8. 0 g 0. 082 The limiting reactant is 2-butanol. gestate Data 2-bromobutane Molecular pack 137. 02 gTheoretical Yield (moles) 0. 081 mol Theoretical Yield (grams) 11. 10 g Actual Yield 10. 11 g NMR Table Signal Chemical Shift Multiplicity Integration A 4. 11 Multiplet 1H B 1. 85 Pentet 2H C 1. 60 Doublet 3H D 1. 08 Triplet 3H Reactivity of Alkyl Halides Compound Observations at Room Temp Observations upon Heating 1-bromobutane puddle Very little change but some face cloth ppt 2 -bromobutane Clear Moderately cloudy white ppt 2-bromo-2-methylpropane Brown tint Very milky white pptCompound Observations at Room temp Observations upon heating 2-chlorobutane Clear No ppt at all 2-bromobutane Clear Moderately white and some yellow ppt 2-iodobutane Dark brown Thick, milky white and yellow ppt decision Overall, the first part of the lab produced 2-bromobutane using SN1 reactions. This product was then used in the second part of the experiment to determine the relative reactivities of alkyl halides. Reactivity increases as follows 1O 2O 3O and Cl- Br- I