Q11 V2The infrared spectrum of cocaine is shown below. From this spectrum it may be concluded that

Question

BlackTom AI · Accepted Answer

To analyze the infrared spectrum question, we need to evaluate what each statement would imply about functional groups present in cocaine based on IR features.
Option a: 'cocaine does not contain C-H bonds' This is unlikely to be true for an organic molecule like cocaine, which contains numerous aliphatic and possibly aromatic C-H bonds. IR spectra typically show C-H stretching bands around 3000–2900 cm-1. The presence of these bands would contradict the statement that there are no C-H bonds.
Option b: 'cocaine does not have the -COOH functional group' In IR spectroscopy, carboxylic acids exhibit a very strong C=O stretching vibration near 1700 cm-1 and a broad O–H stretch from about 2500 to 3300 cm-1 due to hydrogen-bonded OH. If the spectrum shown lacks the characteristic broad, strong C=O band near 1700 cm-1 and the broad OH peak, and instead shows patterns typical of other functional groups (e.g., C–O, C=C, or amine features), this would support the conclusion that there is no -COOH group. In many cocaine IR spectra, the absence of the carboxylic acid signature reinforces this statement.
Option c: 'cocaine is an alcohol' An IR interpretation claiming cocaine is an alcohol would require a strong O–H stretch around 3200–3550 cm-1 and possibly a C–O stretch around 1050–1300 cm-1. However, cocaine’s structure and typical IR features do not point to a simple primary/secondary alcohol signature as the defining characteristic; the spectrum would need to show a specific OH region and related peaks consistent with alcohols. If the spectrum lacks those defining OH features or shows other stronger absorptions, this claim would be dubious.
Option d: 'cocaine does not contain any C-C single bonds' This is highly implausible for an organic molecule like cocaine, which is built from a carbon backbone with many C–C single bonds. An IR spectrum does not usually deny all C–C single bonds, and you would still expect C–H stretches and various C–C related vibrations. This statement contradicts fundamental organic structure and would be inconsistent with typical IR patterns.
In summary, option b correctly interprets the absence of the -COOH signature (no strong 1700 cm-1 C=O and no broad 2500–3300 cm-1 O–H band characteristic of carboxylic acids) and aligns with the general interpretation of cocaine’s IR spectrum. The other options rely on incorrect assumptions about what IR bands must look like for C-H presence, alcohol groups, or C–C frameworks, and thus are not supported by the spectrum shown.

Q11 V2The infrared spectrum of cocaine is shown below. From this spectrum it may be concluded that单项选择题

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