how can i determine via infrared spectrum whether the alcohol that was oxidized was primary or secondary?
i did a lab experiment in which we oxidized a diol with bleach and i need to figure out which -OH group was oxidized into a C=O. What are the signs of whether the -OH is primary or secondary?
To determine whether the alcohol that was oxidized in your lab experiment was primary or secondary using infrared (IR) spectroscopy, you can look for specific peaks or patterns in the infrared spectrum.
Here's how you can approach the analysis:
1. Collect the IR spectrum: Obtain an IR spectrum of your oxidized product. This can be done using an instrument called an infrared spectrophotometer.
2. Analyze the O-H stretch region: In the infrared spectrum, focus on the region between 3500-3200 cm^-1. This region corresponds to the stretching vibrations of O-H bonds. Look for any distinctive peaks or patterns in this region.
3. Primary alcohol: If the O-H bond being oxidized was from a primary alcohol, you will typically observe a strong, broad peak in the range of 3300-3500 cm^-1. This broad peak is due to hydrogen bonding with neighboring molecules. Additionally, primary alcohols tend to show a noticeable peak in the fingerprint region (1500-1000 cm^-1) corresponding to the C-O stretch.
4. Secondary alcohol: In the case of a secondary alcohol, you will generally see a peak between 3600-3650 cm^-1 for the O-H stretch. This peak tends to be narrower and less intense compared to that of primary alcohols. Secondary alcohols also exhibit a C-O stretch peak in the fingerprint region, similar to primary alcohols.
Keep in mind that these are general trends and can vary depending on the specific molecule and other factors. Interpreting IR spectra can be complex, so it is essential to consult reference spectra or work with an expert if needed.
Remember, the information provided here is a general approach, and it is always recommended to follow the guidelines given by your instructor or specific literature references related to your experiment.