1.What specific compound would the silica gel most likely remove from your final
ID: 921171 • Letter: 1
Question
1.What specific compound would the silica gel most likely remove from your final product?
Synthesis and Dehydrohalogenalol lD The present experiment is a two-reaction exercise. You will be synthesizing a haloalkane by a S2 reaction, and then you will carry out a dehydrohalogenation reaction (E2) with the haloalkane. The haloalkane of 2-bromooctane is not that readily available. So, 2-bromooctane will be prepared by heating 2-octanol with hot, concentrated hydrobromic acid. A 1-hour reaction time at 150-155 °C, is necessary to insure a complete reaction with no, or little, 2-octanol remaining, Although the major product for this reaction is the 2-bromooctane, elimination products (octenes, 15%) are for med The elimination products from the dehydrohalogenation reaction are octenes, also. So, the octenes formed in the first reaction are just carried over into the second reaction. In the dehydrohalogenation reaction, a small amount of substitution product (2-ethoxy octane 7%) is formed. This ether product is observed by an absorbance near 1110 cm in the infrared spectrum of the dehy reaction product. With the use of anhydrous sodium sulfate, water is removed from your products. Then, with the use of a With the use of small silica gel column, any remaining ethanol from the 21% sodium ethoxide solution and other polar organic compounds are removed from your dehydrohalogenation product. The relative amounts of the octenes formed from the dehydrohalogenation of 2-bromooctane vary from the octenes formed different from, the acid catalyzed dehydration of2-octanol (experiment #11). This is observedby comparing the infrared spectra of the products from the two experiments. Infrared spectroscopy and refractive index will be used to characterize the final product mixture of this experiment. CH-CH-CH-CH2CHa-CH-CH-CH,HBr CH-CH2-CH2-CH2-CH2-CH2-CH-CH Reaction B CHy-CH2-CHa-CH2-CHz-CH-CH-CH3 +"OCH2CH3 CHj-CH2-CH-CH-CH2-HC-CH-CH, + CH-CH-CH2-CH2-CH-CHa-HC-CH2 + CH-CH2-CH2-CH-CH-CH-CH-CHs Substanse MW emL M.PCa BPCQ Refractive Indes -CHs (t) 2-Octanol ()2-Bromooctane 193.1 1.088 trans-2-Octene 112.2 0.718 Cis-2 1-Octene 130.2 0.819 180 189 189 125 126 121 185 1.4203 1.4442 1.4132 .4150 1.4091 112.2 0.724 112.2 0.715 (+) 2-Ethoxyoctane 158.3 48% Hydrobromic acid 8% sodium bicarbonate 21% sodium ethoxide IM Hydrochloric acid Sodium sulfate, anhydrous 1.48 1.05 Silica gel Revised July 2013 SN2 g47Explanation / Answer
1.
The silica gel generally removes polar organic componds and sodium ethoxide from the product. Therefore, the silica gel removes sodium ethoxide and remaing alcohol (un reacted) from the products. It doesn,t remove the ether.
2.
Yes, During the dehydrohalogenation reaction, small amount of substitution product (ether) is formed. It can't be removed by the silica gel. It remains in the product.
Therefore, a peak in the IR at 1110 cm-1 is obseved which corresponds to an ether.
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