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An organic chemist found a bottle in the laboratory that was labelled 'organic cleaning fluid, C_xH_yO' - VCE - SSCE Chemistry - Question 5 - 2012 - Paper 1
Question 5
An organic chemist found a bottle in the laboratory that was labelled 'organic cleaning fluid, C_xH_yO'. She decided to test the liquid. The chemist obtained the fol... show full transcript
Worked Solution & Example Answer:An organic chemist found a bottle in the laboratory that was labelled 'organic cleaning fluid, C_xH_yO' - VCE - SSCE Chemistry - Question 5 - 2012 - Paper 1
Step 1
How many different carbon environments are present in the compound?
Answer
In the provided data, there are two different carbon environments. The chemical shifts at 1.2 ppm and 2.2 ppm represent distinct carbon environments. The signal at 3.6 ppm also indicates a separate carbon environment due to its different chemical shift.
Step 2
How many different hydrogen environments are present in the compound?
Answer
The 'H NMR data shows there are three different hydrogen environments. The doublet at 1.2 ppm indicates one type of hydrogen environment, the singlet at 2.2 ppm indicates a second type, and the septet at 3.6 ppm indicates the third type.
Step 3
In the 1H NMR spectrum, the signal at 3.6 ppm is split into a septet (7 peaks). What is the number of equivalent protons that are bonded to the adjacent carbon atom(s)?
Answer
The splitting pattern observed indicates that the signal at 3.6 ppm arises from a proton that is adjacent to six equivalent protons on the neighboring carbon atom. This is consistent with the n+1 rule in NMR spectroscopy, where n is the number of equivalent protons on adjacent carbon atoms. Since the septet consists of 7 peaks, n must be 6, leading to 6 equivalent protons.
Step 4
Using the Infrared absorption data on page 7 of the Data Book, identify the atoms that are associated with the absorption labelled A on the infrared spectrum.
Answer
Referring to the infrared spectrum and the absorption data provided, the absorption labelled A is often associated with O-H stretching vibrations, indicative of hydroxyl (–OH) groups typically present in alcohols.
Step 5
Draw a structure of the compound in the cleaning fluid that is consistent with the NMR and IR data.
Answer
Based on the NMR and IR data, a structure consistent with the findings could be derived as follows:
- The compound is likely an alcohol, incorporating an –OH group indicated by the Infrared spectrum.
- Considering the NMR data and peak splitting, a possible structure could be C6H14O, such as 2-heptanol, which has the necessary hydrogen and carbon environments that fit the spectral data.