1. Describe the crystals you have obtained 2. With reference to the optical rotations you recorded...
Fantastic news! We've Found the answer you've been seeking!
Question:
Transcribed Image Text:
1. Describe the crystals you have obtained 2. With reference to the optical rotations you recorded on the polarimeter, discuss the effectiveness of your attempt to separate the two amine enantiomers (optical rotations for the pure single enantiomers, in other words the theoretical values, are: (S) -38.2° and (R) +38.2°). 3. Why is the solution of 1-phenylethanamine hydrogen tartrate not to be cooled in ice water before the crystals are collected? 4. Why cannot racemic tartaric acid be used to resolve 1-phenylethanamine? 5. What is the principle on which the resolution of the racemic 1-phenylethanamines by formation of a tartrate salt depends? 6. If your 1-phenylethylamine is found to have no optical rotation, what is the %ee of your mixture? What percentage of each enantiomer do you have? Experimental Procedure: Week 1: Preparation of Tartarate salt Complexes: 1. Add 7.8 g of L-(+)-tartaric acid and 125 ml of methanot to a 250 ml Erienmeyer flask,. 2. Heat the mixture on a hot plate until the solution is nearly boiling. 3. Carefully add 6.65 ml of racemic I-phenylethylamine to this hot solution if the amine is added to quickly, the mixture may froth and boil over. 4. Remove the solution from the hotplate and place it on a piece of wire gauze on your benchtop. 5. Let the solution cool to room temperature. 6. Seal the flask with parafilm, label it with your names and laboratory section, and place it in the location indicated by your instructor. The solution must now be left to slowly crystallize until next week. Note: The crystals that form slowly should be prismatic if needles form, or crystallization occu rs too quickly, the mixture should be reheated to redissolve the solids, then allowed to cool slowly once again. Week 2: Resolution of enantiomers Part 1: Regeneration of the S-amine 1. Collect the crystals by vacuum filtration and wash the crystals with methanol. Dry the crystals on a piece of large filter paper and record the yield. Do not discard the filtrate! 2. Dissolve the crystals in 50 ml of distilled water in a 100 mL beaker and add 4.5 mL of 50% NaOH solution. Caution: concentrated NaOH is very caustic. Ensure that the solution is basic by testing with pH paper. 3. Transfer the aqueous solution to a separatory funnel and extract with diethyl ether (2x30ml). Perform the extraction technique. Page 5 of 10 Er Flask Diethyl ether is extremely volatile and flammable. When using it for extractions release the pressure after just a few shakes of the funnel and do extractions in the hogd. 66.981 4. Return the aqueous layer to the separatory funnel and repeat the extraction with a second 30 mL portion of ether. 5. Collect the second portion of ether, combine with the ether extract from the first extraction, and then add more anhydrous Nazso, Dry the extracts (ether layer) over anhydrous NazSO, for 10 min. NOTE: Diethyl ether will form H-bonds with water, so there is more water in the ether layer. We have to add more drying agent and wait for a longer time to remove water. 6. Weigh a dry, clean, and empty 250 mL Erlenmeyer flask. Decant the dried extracts into this flask evaporate the ether on a hot plate (about 60°C) in a hood. A stream of air should be directed into the flask to increase the rate of evaporation. When the volume of liquid reaches about 2 or 3 mL total, you should carefully insert a hose attached to the house vacuum or aspirator system to remove any remaining Ether. The hose should be inserted into the neck of the flask. 7. Once the volume of liquid is down to about 2-3 mL, take the flask off the hot plate and weigh the flask again after removing all the solvent and record the weight. The difference of the weights is the amount of your S-amine. Heating the amine in the absence of solvent is likely to promote the reaction of carbon dioxide in the air with it. This reaction forms a white solid, which interferes with the polarimetry measurements, so we are attempting to avoid it by not evaporating all of the solvent with heat. If you do obtain a cloudy solution or solids are present, transfer the material to a centrifuge tube and centrifuge the sample. Polarimetry: Combine your product with the products obtained by three other students. If anyone's product is highly colored or if a large amount of solid is present, do not use it. If the amine is a little cloudy or if there is just a small amount of solid present, transfer the sample to a small centrifuge tube (microcentrifuge tubes work well here) and centrifuge the sample for about 5 minutes. Remove the clear liquid with a Pasteur pipet to avoid drawing up any solid into the pipet and fill a preweighed 10 mL volumetric flask. You will not get good results with the polarimeter if the amine is cloudy or if there are suspended solids present in your amine, so be careful to avoid transferring any ld obtain a value of about 0.94 g/ml. alid 10lninh the flask to determine the weight of amine and calculate the density 1. Describe the crystals you have obtained 2. With reference to the optical rotations you recorded on the polarimeter, discuss the effectiveness of your attempt to separate the two amine enantiomers (optical rotations for the pure single enantiomers, in other words the theoretical values, are: (S) -38.2° and (R) +38.2°). 3. Why is the solution of 1-phenylethanamine hydrogen tartrate not to be cooled in ice water before the crystals are collected? 4. Why cannot racemic tartaric acid be used to resolve 1-phenylethanamine? 5. What is the principle on which the resolution of the racemic 1-phenylethanamines by formation of a tartrate salt depends? 6. If your 1-phenylethylamine is found to have no optical rotation, what is the %ee of your mixture? What percentage of each enantiomer do you have? Experimental Procedure: Week 1: Preparation of Tartarate salt Complexes: 1. Add 7.8 g of L-(+)-tartaric acid and 125 ml of methanot to a 250 ml Erienmeyer flask,. 2. Heat the mixture on a hot plate until the solution is nearly boiling. 3. Carefully add 6.65 ml of racemic I-phenylethylamine to this hot solution if the amine is added to quickly, the mixture may froth and boil over. 4. Remove the solution from the hotplate and place it on a piece of wire gauze on your benchtop. 5. Let the solution cool to room temperature. 6. Seal the flask with parafilm, label it with your names and laboratory section, and place it in the location indicated by your instructor. The solution must now be left to slowly crystallize until next week. Note: The crystals that form slowly should be prismatic if needles form, or crystallization occu rs too quickly, the mixture should be reheated to redissolve the solids, then allowed to cool slowly once again. Week 2: Resolution of enantiomers Part 1: Regeneration of the S-amine 1. Collect the crystals by vacuum filtration and wash the crystals with methanol. Dry the crystals on a piece of large filter paper and record the yield. Do not discard the filtrate! 2. Dissolve the crystals in 50 ml of distilled water in a 100 mL beaker and add 4.5 mL of 50% NaOH solution. Caution: concentrated NaOH is very caustic. Ensure that the solution is basic by testing with pH paper. 3. Transfer the aqueous solution to a separatory funnel and extract with diethyl ether (2x30ml). Perform the extraction technique. Page 5 of 10 Er Flask Diethyl ether is extremely volatile and flammable. When using it for extractions release the pressure after just a few shakes of the funnel and do extractions in the hogd. 66.981 4. Return the aqueous layer to the separatory funnel and repeat the extraction with a second 30 mL portion of ether. 5. Collect the second portion of ether, combine with the ether extract from the first extraction, and then add more anhydrous Nazso, Dry the extracts (ether layer) over anhydrous NazSO, for 10 min. NOTE: Diethyl ether will form H-bonds with water, so there is more water in the ether layer. We have to add more drying agent and wait for a longer time to remove water. 6. Weigh a dry, clean, and empty 250 mL Erlenmeyer flask. Decant the dried extracts into this flask evaporate the ether on a hot plate (about 60°C) in a hood. A stream of air should be directed into the flask to increase the rate of evaporation. When the volume of liquid reaches about 2 or 3 mL total, you should carefully insert a hose attached to the house vacuum or aspirator system to remove any remaining Ether. The hose should be inserted into the neck of the flask. 7. Once the volume of liquid is down to about 2-3 mL, take the flask off the hot plate and weigh the flask again after removing all the solvent and record the weight. The difference of the weights is the amount of your S-amine. Heating the amine in the absence of solvent is likely to promote the reaction of carbon dioxide in the air with it. This reaction forms a white solid, which interferes with the polarimetry measurements, so we are attempting to avoid it by not evaporating all of the solvent with heat. If you do obtain a cloudy solution or solids are present, transfer the material to a centrifuge tube and centrifuge the sample. Polarimetry: Combine your product with the products obtained by three other students. If anyone's product is highly colored or if a large amount of solid is present, do not use it. If the amine is a little cloudy or if there is just a small amount of solid present, transfer the sample to a small centrifuge tube (microcentrifuge tubes work well here) and centrifuge the sample for about 5 minutes. Remove the clear liquid with a Pasteur pipet to avoid drawing up any solid into the pipet and fill a preweighed 10 mL volumetric flask. You will not get good results with the polarimeter if the amine is cloudy or if there are suspended solids present in your amine, so be careful to avoid transferring any ld obtain a value of about 0.94 g/ml. alid 10lninh the flask to determine the weight of amine and calculate the density
Expert Answer:
Related Book For
An Introduction to Statistical Methods and Data Analysis
ISBN: 978-1305269477
7th edition
Authors: R. Lyman Ott, Micheal T. Longnecker
Posted Date:
Students also viewed these mathematics questions
-
With reference to the Audit 11.3 case, how would an understanding of the business and management reporting system have contributed to discovery of the open cash receipts journal cutoff error?
-
With reference to the information provided in Exercises 10.54, 10.55, and 10.57, there was one more question of interest to the researchers. If people in cars with air bags are more likely to be...
-
With reference to the lightning data in Exercise 2.121, (a) Make a time plot of the data. (b) Comment on the appropriateness of presenting the mean and standard deviation as summaries. In Exercise...
-
Find the minimum and maximum values of the function subject to the given constraint. f(x, y) =xy, 4x +9y = 32
-
Construct the Lagrange interpolating polynomials for the following functions, and find a bound for the absolute error on the interval [x0, xn]. a. f (x) = e2x cos 3x, x0 = 0, x1 = 0.3, x2 = 0.6, n =...
-
Evaluate the given integral by changing to polar coordinates. R cos(x 2 + y 2 ) dA, where R is the region that lies above the x-axis within the circle x 2 + y 2 = 9
-
Consider again the ORION system discussed in problem 2. Is ORION an example of descriptive, predictive, or prescriptive analytics? Explain. Problem 2 Every day, logistics companies such as United...
-
The beta coefficient for Stock C is bC = 0.4 and that for Stock D is bD = 0.5. (Stock Ds beta is negative, indicating that its rate of return rises whenever returns on most other stocks fall. There...
-
12-25. The rectangular channel has a width of 1.5 m, and the depth of the water is originally 2 m. If the flow is 4.50 m/s, show that the upstream flow is subcritical, and determine the required...
-
J.D. Power and Associates surveys new automobile owners to learn about the quality of recently purchased vehicles. The following questions were asked in the J.D. Power Initial Quality Survey, May...
-
Activity 1: Crossword Puzzle Across 4. Ratio measuring how expensive a company's stock price is compared to EPS (2 words) 6. Shares bought back from investors 7. Solvency ratio that measures how debt...
-
Use If to define a function that, given a list of numbers, doubles all the positive numbers but leaves the negative numbers unchanged. Rewrite abs to include a specific rule for the case where its...
-
15. Explain the following trends: (i) (ii) toiwo loke Why does fluorine have a smaller atomic radius than beryllium? essa sniwollat pd to doesnt ES Why does fluorine have a smaller atomic radius than...
-
The steel SS1370 with composition must first be carburized and then hardened. It is desired to obtain a hardness HV of 550 at a depth of 2.5 mm below the surface. The carburization takes place in...
-
If it takes 4 seconds to mentally scan the distance between two locations 6 inches apart on a map, how long should it take to mentally scan locations that are 3 inches apart?
-
a) The value of your country's currency has been experiencing a drastic downward decrease in value relative to other major world currencies. In relation to the above statement, discuss four...
-
Marigold Co. loaned Novak Co. $10600, accepting a 4-month, 6.0% promissory note in exchange. On the due date, Novak Co. indicated that it could not pay at the present time. Marigold would make the...
-
Pearl Medavoy will invest $10,240 a year for 20 years in a fund that will earn 10% annual interest. . If the first payment into the fund occurs today, what amount will be in the fund in 20 years? If...
-
Refer to Exercise 13.54. The agronomist is concerned that there may be a distinct difference between the models for land in West Texas and for land in East Texas. Observations 1 23 are data values...
-
The seizure data for the study of Exercise 18.25 are shown here. We have baseline seizure rates, as well as seizure rates for 5 months while on therapy. a. Plot the mean seizure rates by month for...
-
Although an exhaust fan is present in nearly every bathroom, it often is not used due to the high noise level. This is an unfortunate practice because regular use of the fan results in a reduction of...
-
Determine an expansion for the work done in a steady flow adiabatic process.
-
5 m 3 of gas at 8 bar and 180C is heated keeping the pressure same till the volume is doubled. Calculate (a) heat added, (b) external work done, and (c) change in internal energy during the process.
-
A heat engine receives 1000 kW of heat at constant temperature of 285C and rejects heat at 5C . The possible heat rejected are: (a) 840 kW, (b) 442 kW and (c) 300 kW. Comment on the results.
Study smarter with the SolutionInn App