lab/. Lab-7
VCL 2-15: Alkene Bromination-1
By: Michele Hopkins
Ocean County Community College
Chemistry 283
Virtual Chemistry Lab-Organic
10/19/14
Table of contents
Title Page……………………………………. Page 1
Table of Contents…………………………Page 2
Abstract………………………………………. Page 3
Introduction………………………………….Page 3
Experimental Details …………………..Page 4
Results ……………………………………….Page 5
Discussion………………………………….Page 6-7
Conclusion and Summary ………….Page 8
References…………………………………Page 9
Abstract
This lab is used to show how to determine when a reaction has reached completion. It is also used to describe the polarity of the reaction and how to know when the reaction is polar, non-polar, or has intermediate polarity. This lab focuses on determining this using a TLC test, which is performed several times during the reaction. The TLC is also performed using organic material formed. This lab primary goal is to teach about polarity, TLC test, reaction completion, and to teach organic chemistry students some basic chemistry principles as applied in this lab.
Introduction
The purpose of this lab is to prepare a demonstration of the Alkene Halogenation-3. I should be able to notice the outcomes of the change in structures on the reaction results.
Experimental Data
1. The starting materials were obtained from the stock room
a. Round Bottom Flask
b. (Butene) 2-Butene
c. (Bdiene) Buta-1,3-diene
d. Et2O
2. The MCHxene and DMBene were added to the flask
3. The flask was placed on the stir plate
4. Bromine (Br2) was added to the flask along with the other starting materials
5. A heating mantle was added under the flask to heat the mixture
6. A condenser was added to the flask so that the mixture can be refluxed
7. Nitrogen gas was added to maintain inert atmosphere and as well to prevent pressure build up during the reaction
8. The stir Plate was turned on and the reaction started
9. A TLC measurement was done at the begin of the reaction
10. A TLC test was done 15 minutes after the reaction had begun
11. Various TLC test were on at different time intervals as to record when the reaction came to completion.
12. The reaction mixture was added to a separatory funnel
13. H2O aqueous reagent was added to the funnel
14. Two thin layers of organic and aqueous phase were observed in the funnel
15. A TLC measurement was performed on the organic layer in the funnel anti-2,3-dibromo-butane
16. All lab materials were cleaned up and put away
Results
TLC Measurement – Stirred Mixture
10:36 (Start of Reaction) 10:46 11:07 11:12 (complete)
TLC Measument- Funnel Organic TLC –Stired Complete vs. Organic
Organic Stired Organic
IR
NMR
Discussion
During the reaction
Questions
1. Why are the spots the same for both the right and left lanes at the start of the reaction?
a. This is because the reaction has only just begun and a complete reaction has not been yet completed. The reaction in fact has only just begun and we see no product being formed to consume the starting materials.
2. What is the new spot formed after 15 minutes?
a. The new spot is a result of products forming in the reaction.
3. What has happened to the size of the starting material spots? Why? (15 minute point)
4. How much time did it take to complete the reaction?
a. The reaction was started at 10:36am and was observed to be complete by the TLC measurement at 11:12am. This means the entire reaction took 40 minutes. There is however room for error because constant TLC test were on done, but instead done every 5 minutes or so.
5. What are the Rf value for the starting material and products?
6. What can you say about the relative polarities of the starting materials and the products?
Conclusions and Summary
References
Organic Chemistry, Seventh Edition, Paula Yurkanis Bruice
Virtual Chemistry Lab: Organic
Virtual ChemLab v2.5 Organic Synthesis and Organic Qualitative Analysis- Laboratory Workbook Student Manual
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