Orgo 2 Concepts Exam 1

What is IR spectroscopy?

A chemical analytical method that uses differing frequencies of infrared light to detect predictable types of chemical bonds

What is a chemical analytical method that uses differing frequencies of infrared light to detect predictable types of chemical bonds?

IR spectroscopy

In IR spectroscopy, the frequencies will cause certain bonds to _______?

Vibrate

What causes certain bonds to vibrate such as stretching, twisting, wagging, or scissoring?

The frequencies in IR spectroscopy

If the molecule is not symmetrical, e.g. N2, will the bond be observed in the IR spectroscopy

No

In what case would a bond not be observed in the IR spectroscopy?

If the molecule is not symmetrical, e.g. N2

What are the major regions of absorption called?

Fingerprint region and functional group region

Where do the fingerprint and function group regions take place?

Fingerprint region is less than 1500 cm^-1 and the functional group region is more than 1500 cm^-1

What major region of absorption is less than 1500 cm^-1?

Fingerprint region

What major region of absorption is more than 1500 cm^-1?

Functional group region

What bonds do we see in the fingerprint region?

Single bonds such as C-C, C-N, C-O, C-X

What bonds do we see in the functional group region?

Double bonds, triple bonds, single bonds to -H

When describing a peak, you say first word, second word. What do you put for these words?

Length, width

Alkane C-H absorption and intensity

2850-2960 cm^-1, medium

Alkene =C-H absorption and intensity

3020-3100 cm^-1, medium

Alkene C=C absorption and intensity

1640-1680 cm^-1, medium

Alkyne ≡C-H absorption and intensity

3300 cm^-1, strong

Alkyne C≡C absorption and intensity

2100-2260 cm^-1, medium

Alkyl halide C-Cl absorption and intensity

600-800 cm^-1, strong

Alkyl halide C-Br absorption and intensity

500-600 cm^-1, strong

Alcohol O-H absorption and intensity

3400-3650 cm^-1, strong broad

Arene C-H absorption and intensity

3030 cm^-1, weak

Aromatic ring C-C absorption and intensity

1450-1600 cm^-1, medium

Aromatic ring C=C absorption and intensity

1660-2000 cm^-1, weak

Amine N-H absorption and intensity

3300-3500 cm^-1, medium

Amine C-N absorption and intensity

1030-1230 cm^-1, medium

Carbonyl compound C=O absorption and intensity

1670-1820 cm^-1, strong

Aldehyde absorption and intensity

1730 cm^-1, strong

Ketone absorption and intensity

1715 cm^-1, strong

Ester absorption and intensity

1735 cm^-1, strong

Amide absorption and intensity

1690 cm^-1, strong

Carboxylic acid C=O absorption and intensity

1710 cm^-1, strong

Carboxylic acid O-H absorption and intensity

2500-3100 cm^-1, strong broad

Nitrile C≡N absorption and intensity

2210-2260 cm^-1, medium

Nitro NO2 absorption and intensity

1540 cm^-1, strong

What causes intensity?

Change in dipole moment

What does change in dipole moment cause?

Intensity

Alkyl (primary) -CH3 chemical shift

0.7-1.3 δ

Alkyl (secondary) -CH2- chemical shift

1.2-1.6 δ

Alkyl (tertiary) CH chemical shift

1.4-1.8 δ

Allylic chemical shift

1.6-2.2 δ

Methyl ketone chemical shift

2.0-2.4 δ

Aromatic methyl chemical shift

2.4-2.7 δ

Alkynyl chemical shift

2.5-3.0 δ

Alkyl halide chemical shift

2.5-4.0 δ

Alcohol chemical shift

2.5-5.0 δ

Alcohol, ether chemical shift

3.3-4.5 δ

Vinylic chemical shift

4.5-6.5 δ

Aryl chemical shift

6.5-8.0 δ

Aldehyde chemical shift

9.7-10.0 δ

Carboxylic acid chemical shift

11.0-12.0 δ

What region is saturated on proton NMR spectrum?

0.0-1.5 δ

What region is allylic on proton NMR spectrum?

1.5-2.5 δ

What region is halogen on proton NMR spectrum?

2.5-4.5 δ

What region is vinylic on proton NMR spectrum?

4.5-6.5 δ

What region is aromatic on proton NMR spectrum?

6.5-8.0 δ

Ratio of intensities for singlet

1

Ratio of intensities for doublet

1:1

Ratio of intensities for triplet

1:2:1

Ratio of intensities for quartet

1:3:3:1

Ratio of intensities for quintet

1:4:6:4:1

Ratio of intensities for septet

1:6:15:20:15:6:1