2. Determine the weight of your product from reaction B. 3. Calculate the theore

Question

2. Determine the weight of your product from reaction B.

3. Calculate the theoretical yield and percent yield for the octenes from your original weight of 2-octanol.

4. Comment about the comparison of the infrared spectra of 2-octanol, 2-bromooctane, octenes and trans-2-octene, in regard to presence or absence of peaks in trans-2-octene that support the formation of octenes.

5. What is the solid that forms during the second reaction?

6. If you started with 1-octanol, what would be the expected major product for the first reaction (reaction A) and what would be the expected major product for the second reaction ( reaction B)?

7. Why should trans-2-octene be the most abundant product for the dehydrohalogenation reaction?

8. 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 g47

Explanation / Answer

I'll answer question 1 through 3 for reaction A, the rest of your question,post them in a new question.

1. You have then density and volume of both reactants and products so:

mass of 2-octanol = 1.5 * 0.819 = 1.2285 g

Then the moles :

moles = 1.2285 / 130.2 = 0.0094 moles

We have an 1:1 relation so moles of reactant = moles of product.

mass of final product = 0.0094 * 193.1 = 1.822 g

According to your calculations and weights of vial + final product, the product you have was:

25.1071 - 24.5669 = 0.5402 g

%yield = 0.5402 / 1.822 )* 100 = 29.64%

Do the same thing for reaction B, and you'll get the final mass and yield. If you don't know how to do it or get stuck, you may tell me in a comment and I'll gladly do it for you.

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