Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

15. Analytical Techniques:IR, NMR, Mass Spect

IR Spect:Drawing Spectra

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

IR Spect:Drawing Spectra

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Problem 49b

Textbook Question

What functional groups might be present in the IR spectra for the molecules with the given molecular formulas. [Be sure to use the molecular formula in your analysis.]
(b) C₃H₄O₄
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Verified step by step guidance

Start by analyzing the molecular formula C₃H₄O₄. This formula suggests the presence of carbon (C), hydrogen (H), and oxygen (O) atoms. Consider the possible functional groups that can be formed with these elements.

Calculate the degree of unsaturation to determine the number of rings or π bonds. The formula for degree of unsaturation is: \( ext{Degree of Unsaturation} = rac{2C + 2 + N - H - X}{2} \), where C is the number of carbons, N is the number of nitrogens, H is the number of hydrogens, and X is the number of halogens. For C₃H₄O₄, the degree of unsaturation is \( rac{2(3) + 2 - 4}{2} = 2 \). This indicates two degrees of unsaturation, which could be two double bonds, a ring and a double bond, or a triple bond.

Consider the possible functional groups that could be present given the degree of unsaturation and the presence of oxygen atoms. Common oxygen-containing functional groups include carbonyl groups (C=O), carboxylic acids (COOH), esters (COOR), and ethers (C-O-C).

Examine the IR spectra characteristics for these functional groups. Carbonyl groups typically show a strong absorption around 1700 cm⁻¹. Carboxylic acids have a broad O-H stretch around 2500-3000 cm⁻¹ and a C=O stretch around 1700 cm⁻¹. Esters show a C=O stretch around 1735-1750 cm⁻¹ and C-O stretches around 1050-1300 cm⁻¹.

Based on the molecular formula C₃H₄O₄ and the degree of unsaturation, hypothesize which functional groups are most likely present. Consider combinations such as carboxylic acids or esters, which fit the formula and unsaturation degree, and predict their IR spectral features.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Infrared Spectroscopy

Infrared (IR) spectroscopy is a technique used to identify functional groups in organic molecules by measuring the absorption of infrared light. Different functional groups absorb specific frequencies of IR radiation, resulting in characteristic peaks in the IR spectrum. Understanding these peaks allows chemists to deduce the presence of certain functional groups in a compound.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Common functional groups include hydroxyl (-OH), carbonyl (C=O), and carboxyl (-COOH). Identifying these groups in a molecule helps predict its reactivity and properties, which is crucial for interpreting IR spectra.

Molecular Formula Analysis

Analyzing a molecular formula involves determining the possible structures and functional groups that can exist within a given set of atoms. For C₃H₄O₄, potential functional groups include carboxylic acids and esters, as the formula suggests multiple oxygen atoms that could form carbonyl and hydroxyl groups. This analysis guides the interpretation of IR spectra by narrowing down the possible functional groups present.

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Related Practice

Textbook Question

Each of the IR spectra shown below is the spectrum of one of the following compounds. Identify the compound that produced each spectrum.

a. <IMAGE>

Textbook Question

Each of the IR spectra shown below is the spectrum of one of the following compounds. Identify the compound that produced each spectrum.

b. <IMAGE>

Textbook Question

Match each of the four IR spectra to one of the given compounds. [One of the compounds does not match a spectrum.]

(d) <IMAGE>

Textbook Question

Match each of the four IR spectra to one of the given compounds. [One of the compounds does not match a spectrum.]

Textbook Question

Given the IR spectrum, suggest what functional groups might correspond to the given molecular formula.

(d) C₇H₅O

<IMAGE>

Textbook Question

Hoping to make the following diene, a chemist treated the diol shown with acid. Based on the IR spectrum, was the reaction successful? If not, what compound was made instead?

<IMAGE>

Textbook Question

What functional groups are present in a molecule with a molecular formula of C₄H₁₀O and the following IR spectrum? [Use Table 14.2 for this.]

<IMAGE>

Textbook Question

On a day in which the laboratory air conditioning stopped working, a chemist hypothesized that the atmosphere would provide enough ambient heat to drive the nitrile hydrolysis reaction to the carboxylic acid. Based on the IR of the resulting product, was this hypothesis correct?

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What functional groups might be present in the IR spectra for the molecules with the given molecular formulas. [Be sure to use the molecular formula in your analysis.] (b) C₃H₄O₄<IMAGE>

Key Concepts

Infrared Spectroscopy

Functional Groups

Molecular Formula Analysis

Watch next

What functional groups might be present in the IR spectra for the molecules with the given molecular formulas. [Be sure to use the molecular formula in your analysis.]
(b) C₃H₄O₄
<IMAGE>