Green Oxidation of Borneol to Camphor with Oxone Lab Report

Green Oxidation of Borneol to Camphor with Oxone Purpose The goal of this experiment was to oxidize the natural terpene, (1S)-borneol, to (1S)-camphor using green oxidation methods. This included using oxone and NaCl catalyst. The product was purified under sublimation and dried with desiccation. Then the final product was analyzed in Infrared Spectroscopy (IR), proton nuclear magnetic resonance (HNMR), and experimental melting point. The green principles in this reactions include safer reagents, renewable feedstocks, and environmentally benign waste. Reaction Scheme Mechanism In step 1 Oxone oxidizes the chloride forming hypochlorous acid. In step 2 the hypochlorous acid is used to oxidize the borneol to camphor. Oxone is the oxidizing agent and is the one that is reduced in the process. Procedure The procedure was followed as is described in the Wissinger Manual 1 . Some deviations from the manual include performing sublimation on Day 1 prior to desiccation. Also, the sublimation apparatus consisted of a 250-mL round-bottom flask and beaker versus the cold finger method. Reagents Table 2 1(S)-Borneol Oxone KHSO NaCl 1(S)-Camphor Molecular Weight (g/mol) 154.2 614.7 152.2 58.4 152.2 Grams (g) 1.0 2.4 1.18 0.122 0.060 Mols 0.0065 0.004 0.0078 0.002 0.0004 mL 1 2.1 1.03 2.16 0.06 Density (g/ml) 0.99 1.15 1.15 0.902 0.992 bpt/mpt(℃) 210/209 X/70 X/120 1413/801 204/179-182 Solubilities Soluble Soluble Soluble Soluble Soluble Hazards Irritant Corrosive Corrosive X Flammable 5 Results and Observations Observations 1.0 grams of 1(S)-Borneol was mixed with 2.4 grams of Oxone and 0.08 grams of NaCl catalyst was added to speed up the rate of oxidation. After a few minutes the reaction turned a yellow color with a thick liquid consistency. After 50 minutes of stirring the reaction at room temperature, an additional 0.03 grams of NaCl was added and the reaction. Following this was the workup which included purification through sublimation and drying with desiccation. After the workup the aqueous layer was tested with the starch-iodine paper paper and had a dark blue/black color indicating oxidation was not complete. Due to this a scoop full of sodium bisulfite was added until the starch-iodine paper did not show any color. After this the crude product was sublimed using a 250-mL round-bottom flask under a 250-mL beaker wrapped with parafilm paper. During this the flask became foggy which indicated that crystals were forming on the sides of the glass. The product appeared white, shiny, and flakey. This was then tried under a desiccator apparatus using calcium chloride for a few days. Sublimation and Desiccation: Mass Before Sublimation (g) Mass After Sublimation (g) Sublimation % Yield Mass After Desiccation (final) Decisciation % Yield Appearance 0.25 0.071 7.17% 0.060 6.07% White, shiny, and flakey. Yield and Melting Point Theoretical Yield (g) Actual Yield (g) % Yield % Purity (camphor) % Purity (borneol) Corrected % Yield Melting Point Range ℃ Literature Melting Point ℃ 0.989 0.060 6.07% 86.0% 14.0% 4.91% 179-182 177-179 Purity Table Compound Camphor (H Borneol (H a a’ ) ) Chemical Shift (ppm) Integration (cm) Relative #H’s %Purity 0.86 3.4 3 86.0% 0.85 1.6 9 14.0% IR Spectrum (Neat) Compound Bond Vibrations Camphor C=O Stretch Overtone Camphor C-H Stretch (sp Camphor Camphor Camphor Frequency (cm -1 ) Intensity 3468.6 Weak 2958.2/2874.6 Strong C=O Ketone Stretch 1741.5 Strong C-H Bend (CH 2 ) 1450.3 Medium C-H Bend (CH 3 ) 1390.3 Medium 3 ) Discussion/Conclusion 1(S)-Camphor was synthesized under an oxidation reaction of 1.0 grams of 1(S)-Borneol with 2.4 grams of Oxone. Then 0.08 grams of NaCl catalyst was added to speed up the rate of oxidation. After 50 minutes of stirring the reaction at room temperature, an additional 0.03 grams of NaCl was added and 0.25 grams of crude camphor was obtained. Following this was the workup which included purification through sublimation and drying with desiccation. And from this 0.06 grams of camphor was obtained. This was analyzed through IR, HNMR, and experimental melting temperature. The percent yield was 6.07%, this low yield was due to an accidental spill of the crude product during the experiment, where about two-thirds of the product was lost. Using the methyl singlets on the HNMR the percent purity was calculated to be 86.0% with a corrected yield of 4.9%. The HNMR spectrum obtained supports the final product as being 1(S)-Camphor. The spectrum shows three methyl singlet peaks in the upfield region of around 1.0 ppm. The integration of the three methyl peaks H a ,H b and 2.8 cm. The difference of the integration of H , and H a c , of camphor are respectively, 3.4 cm, 2.8 cm, is due to the presence of borneol in the final product indicating impurities. The three methyl groups, H a’ , on borneol have a collective relative number of protons of 9 and are all around 0.85 ppm near the H a . The integration of this borneol peak was 1.6 cm. This was calculated by subtracting the difference from the camphor methyl peak at H a as compared to H b and H c . Using this information the percent purity was calculated to be 86.0% of camphor and 14.0% of borneol. This high purity indicates that the majority of the product was indeed camphor even with a low yield of only 6.07%. There were also two fairly weak peaks associated with borneol, one was a multiplet at 2.30 ppm and the other was a doublet of doublets of doublets in the downfield region of 4.0 ppm. These weak peaks indicate that there was only a small amount of starting material in the final product. IR was used to analyze the functional groups present in the final product. The prominent peaks were the C=O ketone stretch at 1741.5 cm -1 with a strong intensity. This peak provided evidence for the structure of camphor. This peak is higher in wavenumber than the usual which is around 1725-1705 cm -1 , which is due to ring strain. According to Morig, ring strain causes deviations from the position of C=O band for cyclic carbonyl compounds. The position of the absorption band moves to a higher frequency, indicating that the strength of the bond has increased (pg. 334). Similarly, the structure of camphor was supported on the IR by the presence of a weak C=O overtone at 3468.6 cm 3500-3200 cm -1 -1 . In addition, the absence of an O-H peak in the region indicates very little borneol in the final product. Although, there is a weak C-O stretch at 1093.6 cm -1 , which corresponds to the 14% of borneol present in the final product. The experimental melting point was measured to be 179-182℃ compared to the literature melting point of 177-179℃. The reason for the slightly higher measured melting point is because of the 14% of borneol present in the final product. And borneol has a literature melting point of 209℃ which accounts for the slight upward shift because of the borneol impurities in the final product. The crude product was purified under sublimation using a 250-mL round-bottom flask with a 250-mL beaker covered with parafilm. Sublimation was a partially effective way to purify the crude product, even though a significant portion of the material was lost prior to sublimation due to an accidental spill. Through the HNMR there was a high purity of camphor of 86.0% and only 14% of borneol present in the final product. There was no solvent or water present as there were no corresponding peaks on the HNMR. The green chemistry principles that were exemplified in this experiment include safer reagents, renewable feedstocks, and environmentally benign waste. The principle that was not met was atom economy in respect to Oxone reagent. In addition, one major source of error was the loss of crude product prior to purification which resulted in losing two-thirds of the product. Additional questions: Lycopene 4 is a tetraterpenes that contains 8 isoprene units with the molecular formula of C 40 Lycopene is a naturally occurring chemical that gives fruits and vegetables its red pigment called carotenoids. It is found in high amounts in tomatoes but is also found in watermelons, pink grapefruits, and more. In addition lycopene is taken as a supplement for preventing heart disease, cancer, and other diseases. *Structure written by hand. H 64 . Three J values for the ddd for the methine of borneol given on page 82 of the manual: J 1 : (4.030ppm - 3.980ppm)200MHz = 10 Hz J 2 : (4.035ppm - 4.018ppm)200MHz = 3.4 Hz J 3 : (3.985ppm - 3.976ppm)200MHz= 1.8 Hz Yield Calculations (written by hand)