**Analysis:** Peak assignments based on standard FTIR ranges and the theoretical structure of poly(styrene), monocarboxy terminated (polystyrene backbone with a terminal carboxylic acid group).
* **696 cm⁻¹, 752 cm⁻¹:** Match the characteristic out-of-plane C–H bending vibrations of monosubstituted benzene rings (typical for polystyrene: ~760 cm⁻¹ and ~700 cm⁻¹). The strong intensity at 696 cm⁻¹ is consistent. * **1026 cm⁻¹:** Within range for in-plane aromatic C–H bending or C–C skeletal vibrations of the aromatic ring. * **1235 cm⁻¹ (broad):** Could be consistent with C–O stretching of a carboxylic acid, though this band is often stronger and broader for pure acids. The weakness is noted. * **1373 cm⁻¹:** Likely CH deformation (bending) vibrations. * **1450 cm⁻¹, 1491 cm⁻¹:** Correspond to aromatic C=C ring stretching vibrations (typically ~1450, 1490, 1600 cm⁻¹). The absence of a clear peak near 1600 cm⁻¹ is a deviation but not definitive if weak/obscured. * **1733 cm⁻¹:** Directly matches the C=O stretching vibration of a carbonyl group, specifically from a carboxylic acid (ester C=O is typically ~1735-1750 cm⁻¹ as well). The presence of this peak is critical for the "monocarboxy terminated" claim. * **2849 cm⁻¹, 2919 cm⁻¹:** Correspond to symmetric and asymmetric C–H stretching vibrations of aliphatic CH₂ groups (polystyrene backbone). The 2919 cm⁻¹ band is broad, which can be influenced by hydrogen bonding or overlap.
**Critical Mismatches & Assessment:** 1. **Missing Key Polystyrene Band:** The spectrum lacks the definitive, often strong, aromatic C–H stretching bands above 3000 cm⁻¹ (typically ~3025, 3060, 3080 cm⁻¹). Their absence is a significant inconsistency with a polystyrene-based material. 2. **Missing/Weak Carboxylic Acid O–H:** There is no broad, strong absorption band in the 2500-3300 cm⁻¹ region characteristic of the O–H stretching vibration of a carboxylic acid dimer. The weak, sharp peaks at 2849/2919 cm⁻¹ are aliphatic C–H stretches, not O–H. The terminal –COOH group should produce a very discernible O–H stretch. 3. **Weak Carbonyl Signal:** The C=O stretch at 1733 cm⁻¹ is weak (height 0.21). For a terminal functional group expected to be present, a stronger relative intensity might be anticipated, though sample preparation can affect this. 4. **Profile Inconsistency:** The overall spectrum, dominated by a very strong low-wavenumber aromatic peak (696 cm⁻¹) but lacking high-wavenumber aromatic C–H stretches, does not match the typical balanced fingerprint of polystyrene.
**Conclusion:** **Conclusion Two: The sample is NOT Poly(styrene), monocarboxy terminated.**
The provided FTIR data does not support the candidate material. The decisive evidence is the absence of the characteristic aromatic C–H stretching vibrations above 3000 cm⁻¹ and the absence of the broad O–H stretching band of a carboxylic acid group. While some peaks (696, 752, 1450, 1491, 1733, 2849, 2919 cm⁻¹) can be partially assigned to fragments of the proposed structure, their combination and the missing critical bands render the match invalid.
**[Speculation] Regarding possible composition:** The spectrum suggests a material containing an aromatic ring (strong 696 cm⁻¹ peak), aliphatic CH₂/CH₃ groups (2849, 2919 cm⁻¹), and a carbonyl (1733 cm⁻¹) that is likely an ester or ketone (given the lack of associated O–H stretch). The absence of aromatic C–H stretches above 3000 cm⁻¹ could indicate a heavily substituted or non-hydrogen-bearing aromatic system. A compound like an aromatic ester (e.g., a phthalate) is a plausible candidate, but positive identification requires additional data.
This discussion presents an infrared spectral analysis combining
automated interpretation with reference comparison to support
functional group identification and structural assessment.
FTIR Spectrum Interpretation Summary
Comparative Analysis Conclusion
AI-assisted Interpretation Conclusion
**Data → Analysis → Conclusion**
**Data:**
Provided FTIR peaks (cm⁻¹, relative height, qualitative description):
696 (1.00, strong, sharp)
752 (0.30, weak, sharp)
1026 (0.16, weak, sharp)
1235 (0.17, weak, broad)
1373 (0.11, weak, sharp)
1450 (0.21, weak, sharp)
1491 (0.17, weak, sharp)
1733 (0.21, weak, sharp)
2849 (0.11, weak, sharp)
2919 (0.20, weak, broad)
**Analysis:**
Peak assignments based on standard FTIR ranges and the theoretical structure of poly(styrene), monocarboxy terminated (polystyrene backbone with a terminal carboxylic acid group).
* **696 cm⁻¹, 752 cm⁻¹:** Match the characteristic out-of-plane C–H bending vibrations of monosubstituted benzene rings (typical for polystyrene: ~760 cm⁻¹ and ~700 cm⁻¹). The strong intensity at 696 cm⁻¹ is consistent.
* **1026 cm⁻¹:** Within range for in-plane aromatic C–H bending or C–C skeletal vibrations of the aromatic ring.
* **1235 cm⁻¹ (broad):** Could be consistent with C–O stretching of a carboxylic acid, though this band is often stronger and broader for pure acids. The weakness is noted.
* **1373 cm⁻¹:** Likely CH deformation (bending) vibrations.
* **1450 cm⁻¹, 1491 cm⁻¹:** Correspond to aromatic C=C ring stretching vibrations (typically ~1450, 1490, 1600 cm⁻¹). The absence of a clear peak near 1600 cm⁻¹ is a deviation but not definitive if weak/obscured.
* **1733 cm⁻¹:** Directly matches the C=O stretching vibration of a carbonyl group, specifically from a carboxylic acid (ester C=O is typically ~1735-1750 cm⁻¹ as well). The presence of this peak is critical for the "monocarboxy terminated" claim.
* **2849 cm⁻¹, 2919 cm⁻¹:** Correspond to symmetric and asymmetric C–H stretching vibrations of aliphatic CH₂ groups (polystyrene backbone). The 2919 cm⁻¹ band is broad, which can be influenced by hydrogen bonding or overlap.
**Critical Mismatches & Assessment:**
1. **Missing Key Polystyrene Band:** The spectrum lacks the definitive, often strong, aromatic C–H stretching bands above 3000 cm⁻¹ (typically ~3025, 3060, 3080 cm⁻¹). Their absence is a significant inconsistency with a polystyrene-based material.
2. **Missing/Weak Carboxylic Acid O–H:** There is no broad, strong absorption band in the 2500-3300 cm⁻¹ region characteristic of the O–H stretching vibration of a carboxylic acid dimer. The weak, sharp peaks at 2849/2919 cm⁻¹ are aliphatic C–H stretches, not O–H. The terminal –COOH group should produce a very discernible O–H stretch.
3. **Weak Carbonyl Signal:** The C=O stretch at 1733 cm⁻¹ is weak (height 0.21). For a terminal functional group expected to be present, a stronger relative intensity might be anticipated, though sample preparation can affect this.
4. **Profile Inconsistency:** The overall spectrum, dominated by a very strong low-wavenumber aromatic peak (696 cm⁻¹) but lacking high-wavenumber aromatic C–H stretches, does not match the typical balanced fingerprint of polystyrene.
**Conclusion:**
**Conclusion Two: The sample is NOT Poly(styrene), monocarboxy terminated.**
The provided FTIR data does not support the candidate material. The decisive evidence is the absence of the characteristic aromatic C–H stretching vibrations above 3000 cm⁻¹ and the absence of the broad O–H stretching band of a carboxylic acid group. While some peaks (696, 752, 1450, 1491, 1733, 2849, 2919 cm⁻¹) can be partially assigned to fragments of the proposed structure, their combination and the missing critical bands render the match invalid.
**[Speculation] Regarding possible composition:** The spectrum suggests a material containing an aromatic ring (strong 696 cm⁻¹ peak), aliphatic CH₂/CH₃ groups (2849, 2919 cm⁻¹), and a carbonyl (1733 cm⁻¹) that is likely an ester or ketone (given the lack of associated O–H stretch). The absence of aromatic C–H stretches above 3000 cm⁻¹ could indicate a heavily substituted or non-hydrogen-bearing aromatic system. A compound like an aromatic ester (e.g., a phthalate) is a plausible candidate, but positive identification requires additional data.
This discussion presents an infrared spectral analysis combining automated interpretation with reference comparison to support functional group identification and structural assessment.