Substitution Reaction To Perform Synthesis Of 2-Bromoethyl Benzenene

This experiment involved a substitution reaction to perform synthesis of 2-phenylethanol to get (2-bromoethyl)benzene. Using NaBr in an acidic solvent of H2SO4 with H2O present, this synthesis was possible. Subsequent evaluations using TLC and then analyzed samples by Gas Chromatography were done to evaluate the results. Using SN2 reactions, primary alcohol is going to be converted to alkyl halide. Since the reaction can be reversed, the strong sulfuric acid was to make sure the product would indeed be an alkyl halide. This is necessary for a shift towards alkyl halide because the acid dehydrates and it reduces the reactivity of water and also protonates alcohol to speed up the ion production. The first step of the reaction is the protonation
Strong acid can also yield a side reaction of acid and alcohol to produce 2 benzene-ringed ether. To prevent this, with the control of temperature and acid concentration, side reactions are avoidable. After the experiment, Gas chromatography is used to analyze the product sample using its attraction to the stationary phase compared to the mobile phase. After, the sample is vaporized, allowed to travel through tubes using a gas (the two most common gases are helium and nitrogen). The liquid in the sides of the tubes serves as a stationary phase. Attraction to a stationary phase determines how much time the chemicals will spend in this tube phase. Gas chromatography is a very thorough way to view purity of samples. It has an advantage over TLC analysis in that it is more sensitive and yields precise results unlike TLC assumption of Rf values. TLC is still used, though, because it can test multiple samples at the same time whereas GC can only test one at a time. In GC, the two compounds (2-phenylethanol and (2-bromoethyl)benzene) are expected to elute at almost the same time because their boiling points are almost identical, but 2-phenylethanol is a little lower, so it will probably elute first by around one minutes
Using NaBr in very acidic H2SO4 in the presence of H2O, this was made possible. In the SN2 reaction, there was a 0.3999-gram recovery of product. Using TLC analysis and GC MS, figuring out whether the desired product was synthesized became simple. The result of the synthesized product on the TLC plate seemed to have the same markings that the standard samples had, with the exception of a very tiny initial marking at 0.40 cm. This showed that the synthesis, with respect to the TLC analysis, had been properly done. There was a low yield rate for this experiment, 39.21%. This could be from the side reactions occurring and forming other products like the two benzene-ringed ether. If an insatiable amount of NaBr is added in, then there will be this side product. The side reactants present are a very possible reason for a bad product yield. During Reflux, two separate layers had formed, an organic layer on top. It had been on top, though more dense molecules were in it, because Na may have dissolved in water making the aqueous layer denser and subsequently positioning the aqueous layer on the bottom. The gas chromatography showed that there was each kind of isotope present in the mixtures, but at all different abundances. Techniques that could have been improved upon would be making sure to use the proper solutions at proper times, and maybe try harder to prevent side reactions from occurring by