Sort the pairs of related compounds by their carbonyl stretching frequencies in cm–1. (There will be three compounds per bin.)

Bin # 1: Slightly higher
Bin #2: Slightly lower

Compounds:
-butanol
-but-2-enal
-heptan-3-one
-hept-4-en-3-one
-cinnamaldehyde
-3 phenylpropanal

To sort the pairs of related compounds by their carbonyl stretching frequencies, we need to have some basic knowledge about the functional groups present in each compound. The carbonyl stretching frequency is related to the nature of the carbonyl group and the neighboring groups attached to it.

Here's how you can determine the order of compounds based on their carbonyl stretching frequencies:

1. Identify the carbonyl group in each compound. The carbonyl group consists of a carbon atom double-bonded to an oxygen atom (C=O).

2. Determine the neighboring functional groups or atoms attached to the carbonyl group. These neighboring groups can affect the bond strength and hence the stretching frequency of the carbonyl group.

3. Compare the neighboring groups and their effects on the carbonyl stretching frequency. A group that increases the bond strength will result in a higher stretching frequency (cm-1), while a group that decreases the bond strength will result in a lower stretching frequency.

Based on the given compounds, we can analyze each one to determine their order in the two bins:

Bin #1: Slightly higher stretching frequency
1. But-2-enal: This compound contains a conjugated double bond system (-C=C-C=O), which increases the bond strength of the carbonyl group. Therefore, it will likely have a slightly higher stretching frequency.

2. Heptan-3-one: This compound has a simple alkyl chain attached to the carbonyl group. It does not have any conjugation or electron-withdrawing groups, so it will likely have a lower stretching frequency compared to but-2-enal.

3. Cinnamaldehyde: Cinnamaldehyde has a phenyl ring attached to the carbonyl group, which can increase the bond strength. Additionally, it has a conjugated double bond system (-C=C-C=O), further contributing to the increased bond strength. Therefore, it will likely have a slightly higher stretching frequency.

Bin #2: Slightly lower stretching frequency
1. Butanol: Butanol has an -OH group attached to the carbon next to the carbonyl group. The presence of the -OH group weakens the carbonyl bond, resulting in a slightly lower stretching frequency.

2. Hept-4-en-3-one: This compound has both a conjugated double bond system (-C=C-C=O) and a double bond (-C=C-) located away from the carbonyl group. These groups can increase the bond strength, leading to a slightly higher stretching frequency than butanol.

3. 3-phenylpropanal: This compound has a phenyl ring attached to the carbonyl group, potentially increasing the bond strength. However, it does not have any conjugation or additional double bonds, so its stretching frequency will likely be similar to hept-4-en-3-one or slightly lower.

So, the sorted pairs of related compounds by their carbonyl stretching frequencies in cm-1 would be:
Bin #1: Slightly higher - but-2-enal, heptan-3-one, cinnamaldehyde
Bin #2: Slightly lower - butanol, hept-4-en-3-one, 3-phenylpropanal