There are several methods of making naphthalenes, one of which is given in the experimental procedure...
Fantastic news! We've Found the answer you've been seeking!
Question:
Transcribed Image Text:
There are several methods of making naphthalenes, one of which is given in the experimental procedure below. Please read it carefully and answer the questions that follow. OCH3 D[+] (a) H₂CO CH₂O H₂CO OH (b) SUBSTITUTED NAPHTHALENE Step (a): To a solution of 2,4-dimethoxybenzaldehyde ( (5.45 g. 32.80 mmol) and diethyl succinate (8. 18 cm 3, 8.57 g, 49.20 mmol) in dry t-butyl alcohol (80 cm³) stirred under nitrogen, was added potassium-t-butoxide (5.52 g, 49.19 mmol). The mixture was heated under reflux for 2 hours then allowed to cool to room temperature, poured into a separatory funnel containing ice and acidified to pH 3 with cone. HCl(aq). The product thus precipitated was extracted into EtOAc (2x 100 crn³), the combined extracts dried with magnesium sulfate, filtered through Celite and the filtrate concentrated on a rotary evaporator. The resultant oil was purified by column chromatography (10% EtOAc-hexane) to give the desired intermediate that was not characterized but immediately carried through step (b) below. Step (b): To the Stobbe condensation product from step (a) above, dissolved in acetic anhydride (100 cm³), was added anhydrous sodium acetate (6.72 g, 81.91 mmol) and the mixture heated at 140 "C under argon for 2 hours then allowed to cool. Acetic anhydride was removed in vacuo, water (100 cm³) was added, and the product extracted with dichloromethane (3 x 100 cm³). Drying of the combined extracts (MgSO4), filtration through Celite and removal of the solvent on a rotary evaporator gave a dark brown semisolid which was purified by column chromatography (30% EtOAc-hexane, containing 2% v/v dichloromethane) to give an orange-white solid which was recrystallised from EtOAc to give the desired SUBSTITUTED NPHTHALENE (8.10 g) as yellow crystals (mp. 157-158 "C) in two crops. Lit. 158-159 °C. ¹H NMR/300 MHz/8 (ppm): 8.79 (1H, d, J 1.1, 1-H), 7.81 (1H, d, J1.1, 3-H), 6.66 (1H, d, J 1.9, 5-H), 6.51 (1H, d, J 1.9, 7-H), 4.41 (2H, q, J 7.1, OCH₂CH3), 3.97 (3H, s, OCH3), 3.91 (3H, s, OCH₂), 2.45 (3H, s, CH₂COO) and 1.42 (3H, t, J 7.1, OCH₂CH₂). ¹³C NMR/75 MHz/ 6 (ppm): 169.2 (CH CO), 166.2 (ArCOOEt), 160.9 (6-C), 157.8 (8-C), 145.3 (4-C), 131.0 (4a-C), 124.4 (2-C), 123.2 (1-C), 122.2 (80-C), 119.1 (3-C), 98.5 (7-C), 91.6 (5-C), 61.0 (OCH₂CH₂), 55.7 (OCH3), 55.3 (OCH3), 20.9 (CH3COO) and 14.4 (OCH₂CH3). 1. Calculate the percentage yield of step (a), step (b) and the overall yield of the substituted naphthalene over the two steps. [3] 2. Condensation of aromatic aldehydes with diethyl succinate [step (a)] is called Stobbe Condensation. Please give the detailed reaction mechanism for this reaction. [7] 3. What is Celite? Please google it and explain in not more than a few sentences. [3] 4. The Product of step b, the substituted Naphthalene, was purified by column chromatography, followed by recrystallization. How does recrystallization work? Please explain in details. [5] 5. The melting point of the product is given as a range within 1 degree Celsius, and not as one value. Why do you think that is the case? A literature value is also given for comparison; what is the significance of this? [2] 6. On the basis of the given ¹H- and ¹C-NMR spectral data, please decipher the structure of the substituted naphthalene [the product of step (b)]. Give a detailed explanation of how you arrived at the structure. [20] TOTAL 40 MARKS There are several methods of making naphthalenes, one of which is given in the experimental procedure below. Please read it carefully and answer the questions that follow. OCH3 D[+] (a) H₂CO CH₂O H₂CO OH (b) SUBSTITUTED NAPHTHALENE Step (a): To a solution of 2,4-dimethoxybenzaldehyde ( (5.45 g. 32.80 mmol) and diethyl succinate (8. 18 cm 3, 8.57 g, 49.20 mmol) in dry t-butyl alcohol (80 cm³) stirred under nitrogen, was added potassium-t-butoxide (5.52 g, 49.19 mmol). The mixture was heated under reflux for 2 hours then allowed to cool to room temperature, poured into a separatory funnel containing ice and acidified to pH 3 with cone. HCl(aq). The product thus precipitated was extracted into EtOAc (2x 100 crn³), the combined extracts dried with magnesium sulfate, filtered through Celite and the filtrate concentrated on a rotary evaporator. The resultant oil was purified by column chromatography (10% EtOAc-hexane) to give the desired intermediate that was not characterized but immediately carried through step (b) below. Step (b): To the Stobbe condensation product from step (a) above, dissolved in acetic anhydride (100 cm³), was added anhydrous sodium acetate (6.72 g, 81.91 mmol) and the mixture heated at 140 "C under argon for 2 hours then allowed to cool. Acetic anhydride was removed in vacuo, water (100 cm³) was added, and the product extracted with dichloromethane (3 x 100 cm³). Drying of the combined extracts (MgSO4), filtration through Celite and removal of the solvent on a rotary evaporator gave a dark brown semisolid which was purified by column chromatography (30% EtOAc-hexane, containing 2% v/v dichloromethane) to give an orange-white solid which was recrystallised from EtOAc to give the desired SUBSTITUTED NPHTHALENE (8.10 g) as yellow crystals (mp. 157-158 "C) in two crops. Lit. 158-159 °C. ¹H NMR/300 MHz/8 (ppm): 8.79 (1H, d, J 1.1, 1-H), 7.81 (1H, d, J1.1, 3-H), 6.66 (1H, d, J 1.9, 5-H), 6.51 (1H, d, J 1.9, 7-H), 4.41 (2H, q, J 7.1, OCH₂CH3), 3.97 (3H, s, OCH3), 3.91 (3H, s, OCH₂), 2.45 (3H, s, CH₂COO) and 1.42 (3H, t, J 7.1, OCH₂CH₂). ¹³C NMR/75 MHz/ 6 (ppm): 169.2 (CH CO), 166.2 (ArCOOEt), 160.9 (6-C), 157.8 (8-C), 145.3 (4-C), 131.0 (4a-C), 124.4 (2-C), 123.2 (1-C), 122.2 (80-C), 119.1 (3-C), 98.5 (7-C), 91.6 (5-C), 61.0 (OCH₂CH₂), 55.7 (OCH3), 55.3 (OCH3), 20.9 (CH3COO) and 14.4 (OCH₂CH3). 1. Calculate the percentage yield of step (a), step (b) and the overall yield of the substituted naphthalene over the two steps. [3] 2. Condensation of aromatic aldehydes with diethyl succinate [step (a)] is called Stobbe Condensation. Please give the detailed reaction mechanism for this reaction. [7] 3. What is Celite? Please google it and explain in not more than a few sentences. [3] 4. The Product of step b, the substituted Naphthalene, was purified by column chromatography, followed by recrystallization. How does recrystallization work? Please explain in details. [5] 5. The melting point of the product is given as a range within 1 degree Celsius, and not as one value. Why do you think that is the case? A literature value is also given for comparison; what is the significance of this? [2] 6. On the basis of the given ¹H- and ¹C-NMR spectral data, please decipher the structure of the substituted naphthalene [the product of step (b)]. Give a detailed explanation of how you arrived at the structure. [20] TOTAL 40 MARKS
Expert Answer:
Answer rating: 100% (QA)
Solution Consider f0 Since 0 is closed and f continuous f0 ... View the full answer
Posted Date:
Students also viewed these accounting questions
-
Read the following case and answer the questions that follow Employees involved in the accounting and control functions of organizations often face ethical dilemmas. Typically, at some point in each...
-
Read the following passage carefully and answer the questions that follow: When I returned to the common the sun was setting. The crowd about the pit had increased, and stood out black against the...
-
In Problems 1-3, evaluate the integral which is given in cylindrical or spherical coordinates, and describe the region R of integration. 1. 2. 3. r dz dr d0
-
Calculate the heat released as 35.5 g of copper (0.0920 cal/g x C) cools from 50.0 C to 25.0 C.
-
Anvil Ltd. (Anvil) follows IFRS when preparing its financial statements. For each of the following independent situations, explain how Anvil should account for the transaction or economic event....
-
Explain the difference between American and European business executives views on wealth maximization.
-
Potato skins are generated as a by-product in making potato chips and frozen hash browns at Fit Food. The skins are sold to restaurants for use in appetizers. Processing and disposal costs associated...
-
Purkerson, Smith, and Traynor have operated a bookstore for a number of years as a partnership. At the beginning of 2011, capital balances were as follows: Due to a cash shortage, Purkerson invests...
-
Una empresa manufacturera de productos qumicos est implementando un Sistema de Gestin de Seguridad y Salud Ocupacional (SGSSO) basado en la norma OHSAS 18001. La empresa identifica que uno de sus...
-
Create a Decision Tree. You are required to predict the BikeBuyer quotient using any input which has a Score of at least 0.025. Ensure the Content Type is aligned with what Visual Studio recommends....
-
= Consider an economy with a single physical commodity and uncertainty captured by two states of nature S {a,b}. This economy is endowed with markets for two assets with payoffs r = [1 2] and r = [2...
-
Fidelity Investments is one of the largest investment companies in the United States, offering hundreds of alternative funds to its investors. Fidelity Investments is the fund company, or sponsor, of...
-
In September 2014, the SEC filed charges against a roommate and a friend of a hedge fund analyst for insider trading ahead of an announcement that hedge fund Pershing Square Capital Management had...
-
In the late 1990s, growth funds had a big run. With the incredible performance of dot.coms and technology stocks, which are primarily growth stocks, value funds performed poorly relative to growth...
-
Consider the three classes of shares for the MFS Massachusetts Investors Growth Stock Fund, A, B, and C. Each has a different combination of loads, fees, and total annual expenses as follows: Sales...
-
The State Street High Income Fund Class B shares have no upfront sales charge. The fund had a return of 2.6 percent one year when the expense ratio was 2.17 percent. Therefore, before expenses the...
-
A hospital's biomedical repair shop uses a 4-week periodic system to maintain the inventory on the blood pressure cuff repair parts. They use an average 55 adult arm cuffs with a standard deviation...
-
For the following exercises, write the first four terms of the sequence. a n = 2 n 2
-
Do you feel that there are any ethical issues involved when management decides to extend the depreciable life of its long-lived assets in order to increase the firms current net income to a level...
-
Omar Corporation paid \($200,000\) for a tract of land that had an old gas station on it. The gas station was demolished at a cost of \($20,000\) and a new warehouse was constructed on the site at a...
-
During 2016, The Alberta Oil & Gas Company began an exploration project in Montana. The company had paid \($500,000\) for the drilling rights on a tract of 500 acres of land. The company then spent...
Study smarter with the SolutionInn App