Organic Experiments_v3.pdf - Microsoft Edge online.ksu.edu/COMS/player/content/_

Question

Organic Experiments_v3.pdf - Microsoft Edge online.ksu.edu/COMS/player/content/_16794/content/Modules/Organic%20Experiments-v3.pdf Procedure Using your funne, fill 5 ml (d-1.04 gmL) of benzaldehyde (1) and 120 mL of isopropanol (1/2 cup) in the flask. Add 2g of sodium hydroxide (NaOH) to the mixture. Then, add 2 mL of acetone to the mixture. Attach the reflux condenser to the flask and attach the condenserflask to the stand. Make sure that the bottom of the flask does not touch the bottom of your heating pot and that the heating pot is filled with water to the middle of the flask. Make sure that the stand is not in contact with the heating plate or flame (depending on your type of kitchen stove) Turn on the heating source. Fill crushed ice or ice water in the reflux condenser the reflux condenser is cold enough and fil in product in isopropanol cool down to room temperature Heat the solution for 1 h, the water in the heating pot should almost boil. Check that Carefully (HOT) remove the flask from the heating solution. Let the brown reaction Filter the brown filtrate off using the funnel and filter paper, as shown in the video of ser is cold enough and fill in more ice if necessary experiment 9. Let the brown precipitate dry for 30 min. and then fill a sample in one of the sample tubes and label it "P9" (for product of experiment 9) Saep 3 Step 1Sap2 hydroxy- Step 4 Steps 1-5 Step5 Reaction Mechanism of the Formation of Dibenzalacetone Prelab t O Ask me anything 9:06 PM 12/15/2015

Explanation / Answer

In the problem statement you have said

Assuming that you added exactly 5 ml of benzaldehyde (d=1.04 g/ml), how many moles were converted during this reaction? What is the maximal yield of dibenzalacetone that could be performed if we assume 100% yield? Dibenzalaldehye is an organic sunscreen, why?

After reading the picture that you have posted I see that along with 5 ml of benzaldehyde you have 2 ml of acetone. So I will do the mole calculations using these details.

As per the mechanism the reaction requires 2 moles of benzaldehyde for 1 mole of acetone to give one mole of dibenzalacetone

2 ml of acetone (d = 0.791 g/ml, MW 58 g/mol) is 2 x 0.791 = 1.58 g that is 1.58/58 = 0.0272 moles

5 ml benzaldehyde (d=1.04 g/ml, MW is 106 g/mol) is 5 x 1.04 = 5.2 g that is 5.2/106 = 0.049 moles

so the limiting reagent is benzaldehyde

since 2 moles of benzaldehyde gives 1 mole of dibenzalacetone we will get 0.049/2 = 0.024 moles of dibenzalacetone.

MW of dibenzalacetone is 234g/mol so we will have 5.73 g of dibenzalacetone assuming 100% yield.

dibenzalacetone is used in sunscreen because it has a good amount of conjugation of the double bonds. Due to this it can show * and n * where n is a nonbonding lone pair electronic transitions that absorb UV-B light. This UVB light causes sunburn. So since it can absorb UVB it is used in sunscreens.

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.