Question

1. Synthesis of ethyl 4-nitrobenzoate a) In a 50-ml round-bottom flask, weigh out 4-nitrobenzoic acid (0.85 g, 0.005 mol). Add to this 8 ml of absolute ethanol. Add boiling stones, and then bring this solution to the Lab Technologist. WATER OUT b) The Lab Technologist will deliver 1.2 ml of concentrated sulfuric acid to the mixture from the automatic pipette. [CAUTION, SULFURIC ACID IS CORROSIVE, wear gloves] Attach a reflux condenser and reflux the mixture until all the 4-nitrobenzoic acid dissolves (approx. 15-20 min). c) WATER IN d) Remove from heat, and transfer the slightly warm reaction mixture using a pipette into a mixture of 12 g of crushed ice and 12 ml of 10% sodium hydroxide solution. Wait until all the ice melts. e) Collect the resulting precipitate by vacum filtration. Wash once with a small f) Recrystallize the solid from methanol (approx. 3-6 ml). Collect the crystals by g) Determine the mass of product (on pre-weighed watchglass) and calculate the h) Obtain the melting point of your product amount of COLD water. Air-dry on filter. vacuum filtration. Air-dry the crystals on the filter (5-10 minutes). percent yield. produst to YOUr TA for arading and disposal.

Can you explain how to find what is the theoretical yield, and the desired percent yield of ethyl 4-nitrobenzoate?

Answer 1

The reaction is Here, H_2 SO_4 act as catalyst Therefore Density of 100% absolute ethanol = 0.79 g/ml Therefore Ethanol was used = 8 ml times 0.79 g/mol Now, mol as mass of C_2 H_5 OH = 46.1 g/mol Therefore Number of mol of C_2 H_5 OH present in 6.32 g = 6.32 g times 1 mol/46.1 g = 0.137 mol Here given 4 - nitro benzoic acid = 0.005 mol \r\n Now according to stoichiometric ratio of the above reaction 1 mol ethanol react with 1 mol benzoic acid Therefore 0.137 ethanol react with 0.137 benzoic acid But here li-nitro benzoic acid given only 0.05 mol. So, li-nitro benzoic acid is here limiting reagent & the product will be formed according to 4 - nitro benzoic acid According to above reaction 1 mol 4 - nitro benzoic acid yield 1 mol ethyl - 4 - nitro benzoate Therefore 0.005 4 - nitro benzoic acid yield