Using the attached infrared spectroscopy spectrum for the compound Heptanoic Acid, identify the functional group and any observed characteristic absorbtions in cm-1. Compare with the attached roadmap for interpreting IR spectra.

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Using the attached infrared spectroscopy spectrum for the compound Heptanoic Acid, identify the functional group and any observed characteristic absorbtions in cm-1. Compare with the attached roadmap for interpreting IR spectra.

### Heptanoic Acid Infrared Spectrum Analysis

The infrared (IR) spectrum for heptanoic acid is presented in the graph above, which displays transmittance (%T) on the y-axis against wavenumber (cm<sup>-1</sup>) on the x-axis, ranging from 4000 to 650 cm<sup>-1</sup>.

#### Key Peaks and Their Assignments

- **2930.75 cm<sup>-1</sup> and 2858.03 cm<sup>-1</sup>**: These peaks are associated with C-H stretching vibrations common in alkyl chains.
- **1704.75 cm<sup>-1</sup>**: A notable peak signifying C=O stretching vibration, characteristic of carboxylic acids.
- **1412.26 cm<sup>-1</sup> and 1283.53 cm<sup>-1</sup>**: These are likely associated with bending vibrations in aliphatic chains.
- **1206.98 cm<sup>-1</sup> and 1237.74 cm<sup>-1</sup>**: These peaks may correspond to carboxyl group vibrations, indicating C-O stretching.
- **1106.72 cm<sup>-1</sup>**: Often associated with C-O stretching in carboxylic acids.
- **933.85 cm<sup>-1</sup> and 726.32 cm<sup>-1</sup>**: These lower wavenumber peaks could indicate various bending vibrations, potentially linking to alkyl chain motions or other molecular interactions.

This spectrum analysis provides insight into the molecular structure and functional groups present in heptanoic acid, confirming the presence of the carboxylic acid group and aliphatic chains.
Transcribed Image Text:### Heptanoic Acid Infrared Spectrum Analysis The infrared (IR) spectrum for heptanoic acid is presented in the graph above, which displays transmittance (%T) on the y-axis against wavenumber (cm<sup>-1</sup>) on the x-axis, ranging from 4000 to 650 cm<sup>-1</sup>. #### Key Peaks and Their Assignments - **2930.75 cm<sup>-1</sup> and 2858.03 cm<sup>-1</sup>**: These peaks are associated with C-H stretching vibrations common in alkyl chains. - **1704.75 cm<sup>-1</sup>**: A notable peak signifying C=O stretching vibration, characteristic of carboxylic acids. - **1412.26 cm<sup>-1</sup> and 1283.53 cm<sup>-1</sup>**: These are likely associated with bending vibrations in aliphatic chains. - **1206.98 cm<sup>-1</sup> and 1237.74 cm<sup>-1</sup>**: These peaks may correspond to carboxyl group vibrations, indicating C-O stretching. - **1106.72 cm<sup>-1</sup>**: Often associated with C-O stretching in carboxylic acids. - **933.85 cm<sup>-1</sup> and 726.32 cm<sup>-1</sup>**: These lower wavenumber peaks could indicate various bending vibrations, potentially linking to alkyl chain motions or other molecular interactions. This spectrum analysis provides insight into the molecular structure and functional groups present in heptanoic acid, confirming the presence of the carboxylic acid group and aliphatic chains.
### Infrared Spectroscopy Guide

#### I. Identifying Carbonyl Groups (C=O)

1. **Check for Carbonyl Absorption**: 
   - Look for strong absorption between 1750 to 1650 cm<sup>-1</sup>.

2. **Carbonyl Functional Group Identification**:
   - **Carboxylic Acids**: Broad, strong absorption (3300-2500 cm<sup>-1</sup>) due to O-H stretch.
   - **Aldehydes**: Two medium peaks around 2780 and 2670 cm<sup>-1</sup> (may include aliphatic C-H stretch).
   - **Amides**: Absorption around 1670 cm<sup>-1</sup>, possibly accompanied by N-H stretch (3050-3550 cm<sup>-1</sup>).

3. **Carbonyl Position Determination** (if I.A options are ruled out):
   - **Anhydrides**: Two peaks in the carbonyl range.
   - **Ketones and Esters**: Stretching band usually at frequencies higher than 1725 cm<sup>-1</sup>.

#### II. Absence of Carbonyl Absorption

1. **Check for N-H Stretching Bands** (higher than 3100 cm<sup>-1</sup>):
   - **Primary Amines**: Two peaks.
   - **Secondary Amines**: One peak.
   - **Tertiary Amines**: No absorption here.

2. **O-H Stretching in Alcohols**:
   - "Free" O-H: Around 3600 cm<sup>-1</sup> (broad, strong).
   - "Hydrogen-bonded" O-H: Around 3400 cm<sup>-1</sup> (broad, strong).

#### III. Triple Bonds

- **Acetylenes**: C≡C stretch at about 2100-2260 cm<sup>-1</sup>.
- **Nitriles**: Similar band at about 2200-2300 cm<sup>-1</sup>.

#### IV. C-H Stretching

1. **Aliphatic C-H Stretch**: Intense absorption slightly less than 3030 cm<sup>-1</sup>.
2. **Aromatic & Alkene C-H Stretch**: Weaker absorption slightly
Transcribed Image Text:### Infrared Spectroscopy Guide #### I. Identifying Carbonyl Groups (C=O) 1. **Check for Carbonyl Absorption**: - Look for strong absorption between 1750 to 1650 cm<sup>-1</sup>. 2. **Carbonyl Functional Group Identification**: - **Carboxylic Acids**: Broad, strong absorption (3300-2500 cm<sup>-1</sup>) due to O-H stretch. - **Aldehydes**: Two medium peaks around 2780 and 2670 cm<sup>-1</sup> (may include aliphatic C-H stretch). - **Amides**: Absorption around 1670 cm<sup>-1</sup>, possibly accompanied by N-H stretch (3050-3550 cm<sup>-1</sup>). 3. **Carbonyl Position Determination** (if I.A options are ruled out): - **Anhydrides**: Two peaks in the carbonyl range. - **Ketones and Esters**: Stretching band usually at frequencies higher than 1725 cm<sup>-1</sup>. #### II. Absence of Carbonyl Absorption 1. **Check for N-H Stretching Bands** (higher than 3100 cm<sup>-1</sup>): - **Primary Amines**: Two peaks. - **Secondary Amines**: One peak. - **Tertiary Amines**: No absorption here. 2. **O-H Stretching in Alcohols**: - "Free" O-H: Around 3600 cm<sup>-1</sup> (broad, strong). - "Hydrogen-bonded" O-H: Around 3400 cm<sup>-1</sup> (broad, strong). #### III. Triple Bonds - **Acetylenes**: C≡C stretch at about 2100-2260 cm<sup>-1</sup>. - **Nitriles**: Similar band at about 2200-2300 cm<sup>-1</sup>. #### IV. C-H Stretching 1. **Aliphatic C-H Stretch**: Intense absorption slightly less than 3030 cm<sup>-1</sup>. 2. **Aromatic & Alkene C-H Stretch**: Weaker absorption slightly
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