Orgo 2 lab 1 - Lab report PDF

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Lab 1: Reduction of Camphor to Borneol and Isoborneol Introduction: In order to reduce camphor into isoborneol and borneol, sodium borohydride and methanol can be used. This is done as sodium borohydride gives a hydrogen ion to camphor causing it to lose its carbonyl group, and form an alcohol. When the hydrogen ion attacks, it can either perform an endo attack from the bottom, or an exo attack from the top. Afterwards, the oxygen ion turns into an alcohol after methanol protonates it. When attacking from the bottom through endo attack, isoborneol is produced. When attacking from the top through exo attack, borneol is produced. Due to steric hindrance of the two methyl groups and bridge, attacking from the top is less likely to succeed than attacking from the bottom, where only one methyl group is present.

Results and Observations: Erlenmeyer flask mass: 24.52g Ernlenmeyer flask + product: 24.64g Mass of product: 24.64g-24.52g=0.12g Substance

Literature Value (°C)

Observed Melting point (°C)

Camphor

170°

158°-159°

Borneol/Isoborneol mixture

220°

208°-211°

This IR spectroscopy graph does not show a peak at 1720, indicating the loss of the carbonyl group.

The NMR ratio indicates Borneol to be 25% and isoborneol to be 75% of the product.

Treatment of results:

OC H 3 ¿ 4 4 C 10 H 16 O+ NaB H 4 + 4 C H 3 OH → 4 C 10 H 18 O+NaB ¿

Theoretical yield: Moles of camphor: 0.25g / (152.23g/mol) = 0.0016 moles Moles of sodium borohydride: 0.25g / (37.83g/mol) = 0.066 moles Camphor is the limiting reagent, so product is also 0.0016 moles Grams borneol/isoborneol: 0.0016 mol * 154.25g/mol = 0.2533g Actual yield= 0.12g Percent yield= 0.12g/0.2533g *100% = 47.37% Discussion/Conclusion: As the reaction proceeds, the hydrogen from sodium borohydride conducts nucleophilic attack on the camphor. This causes the pi bond from the carbonyl to shift to the oxygen. The methanol is then able to protonate the oxygen due to its negative charge. The major product for this reaction is isoborneol because endo attack from the bottom is favored as there is less steric hindrance at the bottom. The top has 2 methyl groups, whereas the bottom only has 1.

The melting point showed that the products were pure due to the narrow melting point range. Though it differed from the literature value, this may have been due to the fact that our observed melting point for camphor was also less than the literature value. In addition, our obtained IR showed that the carbonyl group was no longer present in the product, meaning that the hydrogen from sodium borohydride has successfully attacked the structure. The alcohol peak around 3300 however, did not appear, meaning that the reaction did not proceed fully to completion. This may have been due to the fact that the methanol did not react to protonate the oxygen ion. This could have been due to error in not using enough methanol. Furthermore, the NMR spectrum showed us that isoborneol is the major product of this reaction. This is because the hydrogen peak at 4ppm (Borneol) had an integration value of 0.25, whereas the hydrogen peak at 3.6ppm had an integration value of 1.0 (isoborneol). This indicates that there is four times more isoborneol formed as a product than borneol, making borneol the minor product and isoborneol the major product. References: 1) Brown, Muzzio. “An Oxidation-Reduction Scheme: Borneol, Camphor, Isoborneol1.” J Penn, 2012, www.as.wvu.edu/~jpenn/Chem%20339/Experiments/Exp

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