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An organic chemist found a bottle in the laboratory that was labelled 'organic cleaning fluid, CxHyO' - 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, CxHyO'. She decided to test the liquid. The chemist obtained the follo... show full transcript
Worked Solution & Example Answer:An organic chemist found a bottle in the laboratory that was labelled 'organic cleaning fluid, CxHyO' - VCE - SSCE Chemistry - Question 5 - 2012 - Paper 1
Step 1
How many different carbon environments are present in the compound?
Answer
In the provided 13C NMR spectrum, we need to analyze the distinct chemical shifts observed. The 1.2 ppm signal represents one carbon environment, as it corresponds to a doublet (6 protons). The 2.2 ppm signal indicates a singlet, suggesting another distinct carbon environment. Lastly, in the 3.6 ppm region, a unique carbon atom generates a signal for the septet, indicating further neighboring protons. Therefore, there are three different carbon environments present in the compound.
Step 2
How many different hydrogen environments are present in the compound?
Answer
The analysis of the 1H NMR information shows there are three different peaks indicating distinct hydrogen environments. The peak at 1.2 ppm (doublet) signifies two equivalent protons, while the 2.2 ppm (singlet) shows a unique environment for one proton. The 3.6 ppm peak (septet) suggests a more complex environment, contributing to the total number of different hydrogen environments. Thus, there are three distinctive hydrogen environments in the compound.
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 integration of the 3.6 ppm signal reveals that it is split into a septet, indicating that there are six equivalent protons on the neighboring carbon. According to the n+1 rule for splitting in NMR, where n corresponds to the number of equivalent protons on adjacent carbon atoms, we can deduce that if the signal is split into a septet (7 peaks), the adjacent carbon atom must have 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 IR spectrum data, absorption band labeled A occurs in the region typically associated with O-H stretchings, indicating the presence of a hydroxyl group (–OH). The atoms associated with this absorption would therefore include the oxygen atom bonded to a hydrogen atom.
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 previously analyzed NMR and IR data, the structure of the compound can be deduced as follows: a carbon chain with a hydroxyl group attached. The three distinct carbon environments correspond to a structure that could potentially resemble a 2-hexanol, with the appropriate number of protons indicated by the NMR data. The carbon skeleton supports the three hydrogen environments, particularly with a -CH2- group adjacent to the –OH.