Oxidation of Benzoin to Benzil

Shao 1 Jonathan Shao TA: Jake Black/Friday Date: 02/06/2015 EP2-2: Oxidation of Benzoin to Benzil using Nitric Acid GOALS: 1) to synthesize benzil through oxidation of benzoin using nitric acid 2) to purify the product using recrystallization and vacuum filtration 3) to test the purity using TLC, MP, and IR Chemical Reaction Scheme:[1]

Mechanism:[1]

Table of chemical physical and chemical properties[1]* Chemical MW BP/MP SG OR structure/formula/name g/mol °C DENSITY G/ML (25°C) Nitric Acid[2] HNO3

63.01

100/NA

1.48

AMT REQUIRED / AMT PRODUCE D 4.5 mL

Acetic Acid[3] C2H4O2

60.05

117118/16.2

1.049

3.0 mL

Hazard/ Precaution

Corrosive/avoid skin contact

Corrosive/avoid skin contact

Shao 2

Benzil[4] C14H10O2

CONTINUED ON PAGE 2 CONTINUED FROM PAGE 1 210.2 NA/94-95 NA Theoretical: 3 0.59 g

Irritant/avoid contact

95% ethanol[5] CH3CH2OH

46.07

78.5/ -114.1

0.789

As needed

Flammable/avoi d heat, skin contact

Ethyl acetate[6] C4H8O2

88.11

77/-83

0.902

~2 mL

Flammable, toxic/avoid heat, ingestion

Benzoin[7] C14H12O2

212.2 6

343/137

1.31

0.60 g

Irritant/avoid inhalation

Hexane[8] C6H14

86.18

68/-95

0.66

~2 mL

Flammable/avoi d heat

Nitric oxide[9] NO

46.01

21/-11

2.62

---

Toxic/avoid inhalation and skin contact.

Nitrogen dioxide[10] NO2

30.01

-151.7/ -163.6

NA

---

Toxic/avoid inhalation and skin contact

*References and notes: all SDS information was obtained from online Sigma Aldrich catalog. Each substance’s specifically referenced SDS is included in the references section. Images obtained through ChemDraw. Theoretical Yield: limiting reagent = Benzoin 1 mol of Benzoin reacts to form one mol of Benzil (0.60 g Benzoin) x (1mol/ 212.26 g) x (210.23 g/mol Benzil) = 0.59426 or 0.59 grams Benzil Procedure:[1] 1. Heat a water bath to 95°C.

Shao 3 2. Add 4.5 mL of concentrated nitric acid and 3.0 mL of acetic acid to 0.6 g of dry benzoin in a 50 mL Erlenmeyer flask. Add stir bar and clamp to hot water bath. Continue heating and stirring for 30-40 minutes. CONTINUED ON PAGE 3 CONTINUED FROM PAGE 2 3. When evolution of red-brown nitrogen oxides has ceased, pour cooled reaction mix into a beaker with 20 mL ice cold water and stir with glass rod for 1-2 minutes to precipitate the yellow solid. 4. Collect product via vacuum filtration and rinse product with cold water until no longer acidic. Recrystallize with hot ethanol and room temperature water. Collect crystals via vacuum filtration. 5. Run TLC, MP, and IR of product. Divide product with partner. Clean Up:[1]  Acidic filtrate should be neutralized by transferring to large beaker of water and adding sodium bicarbonate and pouring down drain with heavy flow of water  All solvents go into the organic waste References: 1. DiMeglio, C. Course Packet for Organic Chemistry Laboratory, Spring 2015; Yale University, Department of Chemistry: New Haven, 2015 2. Nitric Acid; Safety Data Sheet No. 7697-37-2; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/sial/258121?lang=en®ion=US (accessed February 5, 2015) 3. Acetic Acid; Safety Data Sheet No. 64-19-7; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/sial/a6283?lang=en®ion=US (accessed February 5, 2015) 4. Benzil; Safety Data Sheet No. 134-81-6; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/aldrich/b5151?lang=en®ion=US (accessed February 5, 2015) 5. Ethanol; Safety Data Sheet No. 64-17-5; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/sial/16368?lang=en®ion=US (accessed February 5, 2015) 6. Ethyl Acetate; Safety Data Sheet No. 141-78-6; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/aldrich/w241407?lang=en®ion=US (accessed February 5, 2015) 7. Benzoin; Safety Data Sheet No. 119-53-9; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/aldrich/b8681?lang=en®ion=US (accessed February 5, 2015) 8. Hexane; Safety Data Sheet No. 110-54-3; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/sial/296090?lang=en®ion=US (accessed February 5, 2015) 9. Nitric Oxide; Safety Data Sheet No. 10102-43-9; Sigma-Aldrich; http://www.sigmaaldrich.com/catalog/product/aldrich/295566?lang=en®ion=US (accessed February 4, 2015)

Shao 4 10. Nitrogen Dioxide; Safety Data Sheet No. 10102-44-0; Sigma Aldrich; http://www.sigmaaldrich.com/catalog/product/aldrich/295582?lang=en®ion=US (accessed February 4, 2015) END EP2-2