December 7th, 2015
The Reduction of Carbonyl Compounds
Introduction This experiment was executed to study the reduction of a ketone to produce a secondary alcohol. This can be seen in Equation 1 below:
Using sodium borohydride (NaBH4) as a reducing agent, the starting molecule of 9-fluorenone was reduced to 9-fluorenol. In Equation 2 shown below, the sodium borohydride is used to reduce the C=O bonds to C-OH bonds.
The objective of this experiment was to not only reduce 9-fluorenone to 9-fluorenol, but also to analyze the product through melting point analysis and IR spectroscopy and to determine the success of the reaction. By comparing the evaluated melting point of the product sample…show more content… Table 1. Measured Melting Point and Accepted Value for 9-fluorenol According to Fisher Scientific.
Measured Melting Point (ºC) Accepted Melting Point (ºC)
Figure 1 illustrates the spectrum for the starting material of 9-fluorenone. The relevant peaks are shown and only C=O bonds are found in 9-fluorenone (see attached). Figure 2 displays the IR spectroscopy results for the pure samples of 9-fluorenol. The relevant peaks that were present in 9-fluorenol are shown and only C-OH bonds were present (see attached). Figure 3 provides the spectrum for the sample product of the experiment performed. This figure shows that the only peaks that were present were for C-OH bonds (see attached). In order to test the identity of the product sample, an Infrared Spectroscopy was performed. Table 2 provides the wavelengths for the peaks seen in the spectra for the starting material 9-fluorenone, the known pure 9-fluorenol, and the product sample. This table displays which bonds exist in each compound. Table 2. Wavelengths and Relevant Peaks for each Spectra
Molecule C=O Wavelength (cm-1) C-OH Wavelength (cm-1)
9-Fluorenone 1700…show more content… As shown in Table 1, there was a discrepancy of approximately 0.2ºC between the measured melting point and the accepting melting point for 9-fluorenol. Because the measured melting point was within 5°C of the accepted melting point, the product was very likely to be 9-fluorenol. The product was proven to be pure due to the fact that the range of the melting point was less than 2°C. Infrared Spectroscopy was used to analyze the end product of this reaction as well as identify the types of bonds present in each sample. The spectrum for 9-fluorenone illustrated that C=O bonds were the only bonds existing in the sample, as shown in Figure 1. As displayed in Figure 2, only C-OH bonds were present in the pure sample of 9-fluorenol. Moreover, no C=O bonds were present in the end product of the experiment and only C-OH bonds were present. Thus, the IR spectroscopy indicated that this experiment was successful in carrying out the reduction of 9-fluorenone to