Converting Butanol To Butyl Bromide by Nucleophilic Substitution PDF

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Converting Butanol To Butyl Bromide by Nucleophilic Substitution Lab report
Introduction, Materials, Methods, Data, Results, Discussion, Conclusion.
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Experiment: Converting Butanol To Butyl Bromide by Nucleophilic Substitution Date Performed: April 22, 2020 Date Submitted: April 26, 2020 Organic Chemistry CHEM 2223L

Introduction: The purpose of this experiment is to convert Butanol to Butyl Bromide by nucleophilic substitution. The procedure to get Butyl bromide from Butanol is done in two parts. The first part of the experiment involves the formation of n-butyl bromide from 1-butanol. In the second part of the experiment the n-butyl bromide produced in the first part is being converted into n-butyl ethyl ether by using methanol and sodium hydroxide. The reaction for parts 1 and 2 are shown below: Part 1: CH3-CH2-CH2-CH2-OH +NaBr + H2SO3 → CH3-CH2-CH2-CH2-Br+NaHSO4+H2O  Part 2: C4H9Br → CH3(CH2)3-O-C2H5

An Alkyl halide is used. The displacement of a hydroxyl group by halide ion is successful only in the presence of a strong acid. 1-butanol is used to be converted into 1-bromobutane with the addition of Sodium bromide and Sulphuric acid. The nucleophile for the reaction is Br- ions. The nucleophile in this lab is generated from an aqueous solution of sodium bromide. The sulfuric acid acts as a catalyst in this reaction. The Sulphuric acid protonates 1-butanol to produce the leaving group, OH, in SN2 reaction. In the second part of the experiment the mechanism of synthesis of ether used is known as the mechanism of Williamson ether synthesis. In this mechanism one alkoxide reacts with alkyl bromide to form ether with two alkyl groups by using a strong base. For the synthesis of n-butyl ethyl ether, both reactions undergo SN2.

Materials:

● 1-butanol

● Anti-bumping granules

● Condenser

● Anhydrous Calcium chloride

● 95% ethanol

● 5% aqueous Sodium bisulfate

● Thermometer

● Anhydrous Magnesium sulphate

● Sulphuric acid

● 10% aqueous Sodium carbonate

● Bunsen burner

● Round bottomed flasks (50cm3 and

● Distilled water

250cm3)

● Sodium bromide ● Separatory funnel ● Sodium hydroxide

Procedure: 1. 27g of sodium bromide, 30cm3 of water and 20cm3 of 1-butanol are placed into a 2. 250cm3 round bottom flask. 3. The mixture is cooled in an ice bath and 25cm3 conc. sulphuric acid is added with continuous swirling. 4. Two or three anti-bumping granules are added and attached with a gas trap to prevent HBr escaping, the round bottom flask is heated vigorously under reflux for 1.5 hours as shown in diagram 1 below. 5. Distill the two layered mixture until the temperature reaches the boiling point of water. 6. The distillate is transferred to a separating funnel and shakes with an equal volume of 5% aqueous Sodium bisulfate. 7. Allow the two layers to separate and wash the organic layer twice with 25cm3 water followed by 10% aqueous sodium carbonate (25cm3 ).

8. The product is dried with 5g Calcium chloride and is filtered into 50cm3 round bottom flask. 9. Anti bumping granules are added and distilled, the material which boiled between 90-105 C is collected. 10. The appearance of product is noted and weight is measured. 11. 4g of Sodium hydroxide and 12cm3 95% of ethanol are added into round bottom flask and is heated under reflux for 20 minutes. 12. 10cm3 n-butyl bromide is added into the mixture through the top of the condenser and the reaction is heated under reflux for 90 minutes. 13. After cooling, the mixture is transferred to a separating funnel and 50cm3 of water is added which has been used to rinse the reaction flask. 14. The mixture is mixed and the lower layer is removed. 15. The washing is repeated for two times with 20cm3 of water. 16. The organic layer is dried with anhydrous Magnesium sulphate and the liquid is filtered into a 50cm3 round bottom flask. 17. The product is distilled slowly; the material which boiled in the range 90-96 C  is collected in a pre-weighed flask. 18. The density of the pure ethyl n-butyl ether is determined by pipetting 1cm3 liquid into a pre-weighed measuring cylinder and noting the weight difference....