Organic Chemistry: Exam 2 (IR Spectroscopy, NMR Spectroscopy, MS Spectrometry)

At what frequency are double bonds found? Between _____-_____ cm^-1

1600-1850

At what frequency are triple bonds found? Between _____-_____ cm^-1

2100-2300

At what frequency are Z-H bonds found? Between _____-_____ cm^-1

2700-4000

IR Spectroscopy

Focuses on energy gaps between vibrational excitations of bonds to identify functional groups

NMR spectroscopy

Focuses on the nuclei of atoms, includes 1H NMR and 13C NMR

Spectroscopy

The study of the interaction between matter and electromagnetic raditaion

In NMR spectroscopy, alkanes are generally found at what ppm?

1-2

In NMR spectroscopy, aromataic rings are generally found at what ppm?

Around 7

In NMR spectroscopy, a methyl group (A carbon attached to 3 hydrogens) is generally found at what ppm?

0.9

In NMR spectroscopy, a methylene group (A carbon attached to 2 hydrogens) is generally found at what ppm?

1.2

In NMR spectroscopy, a methine group (A carbon attached to 1 hydrogen) is generally found at what ppm?

1.7

In NMR spectroscopy, the alpha position refers to the most significant part of the atom. A significant atom has a stronger signal because of

Electronegativity

In NMR spectroscopy, the presence of an oxygen of either alcohol or ether adds _____ to the alpha position of methyl, methylene, or methine groups and _____ to the beta position

2.5, 0.5

In NMR spectroscopy, the presence of an oxygen of an ester adds _____ to the alpha position of methyl, methylene, or methine groups and _____ to the beta position

3, 0.6

In NMR spectroscopy, the presence of a C=O adds _____ to the alpha position of methyl, methylene, or methine groups and _____ to the beta position

1, 0.2

Define Mass Spectrometry

The study of the interaction between matter and an energy source other than electromagnetic radiation.

What is mass spectrometry primarily used to determine?

The molecular weight and molecular formula of a compound

HDI stands for

Hydrogen Deficiency Index

Define HDI

A measure of the number of degrees of unsaturation in a compound

An HDI of 0 means

no rings or pi bonds

An HDI of 1 means

Either 1 ring or 1 pi bond

An HDI of 2 means

Either 2 pi bonds, 2 rings, 1 pi bond and 1 ring, or 1 triple bond

In mass spectrometry, the x axis is _____ and the y axis is _____

mass/charge, relative intensity

In IR spectroscopy, the x axis is _____ and the y axis is _____

wavenumber, % transmittance

In NMR spectroscopy, the x axis is _____, measured in _____

chemical shift (ppm)

In NMR spectroscopy, the left is for _____, or _____ protons

Downfield, deshielded

In NMR spectroscopy, the right is for _____, or _____ protons

Upfield, shielded

In a 1H NMR spectrum, each signal has 3 important characteristics. What are they?

Location, area, shape

In NMR spectroscopy, Protons that occupy identical electronic environments and produce only one signal are

chemically equivalent

In NMR spectroscopy, When two protons are interchangeable by rotational symmetry, the protons are said to be

Homotopic

In NMR spectroscopy, When two protons are interchangeable by reflectional symmetry, the protons are said to be

enantiotopic

True or false: In NMR spectroscopy, If two protons are neither homotopic nor enantiotopic, then they are not chemically equivalent

True

In NMR spectroscopy, The replacement test is a simple technique for verifying the relationship between protons. If the replacement test produces diastereomers, then the protons are

diastereotopic

In NMR spectroscopy, The _____, or area under reach signal indicates the number of protons giving rise to the signal. These numbers provide the relative number, or ratio, of protons giving rise to each signal.

Integration

In NMR spectroscopy, _____ represents the number of peaks in a singal. A _____ has one peak, a _____ has two, a _____ has three, a ______ has four, and a _____ has five

Multiplicity, singlet, doublet, triplet, quartet, quintet

In NMR spectroscopy, Multiplicity is the result of ______, also called ______, which follows the n+1 rule

spin-spin splitting, coupling

In NMR spectroscopy, _____ do not split each other

Equivalent

In NMR spectroscopy, in order for protons to split each other, they must be separated by no more than _____ sigma bonds

3

In NMR spectroscopy, when signal splitting occurs, the distance between the individual peaks of a signal is called the _____, or _____, and is measured in hertz

coupling constant, J value

In NMR spectroscopy, complex splitting occurs when a proton has two different kinds of neighbors, often producing a

multiplet

What percentage of carbon atoms are 13C?

1.1

In 13C NMR spectroscopy, chemical shift values typically range from

0-220

The number of signals in a 13C NMR spectrum represents the number of carbon atoms in different _______ ______ (carbon atoms that are not interchangeable by symmetry). Carbon atoms that are interchangeable by symmetry operation (either rotation or reflection) will only produce one signal.

electronic environments

In IR spectroscopy, C=O bonds produce _____ signals while C=C bonds produce _____ signals

strong, weak

True or false: In IR spectroscopy, smmetrical C=C and bonds do not produce signals. The same is true for symmetrical triple bonds.

True

In IR spectroscopy, concentrated alcohols give rise to _____ signals, while dilute alochols give rise to _____ signals

Broad, narrow

In Mass Spectrometry (MS), the nitrogen rule says that an odd molecular weight indicates an _____ number of nitrogen atoms, while an even molecular weight indicates 0 or an _____ number of nitrogens

odd, even

In Mass Spectrometry (MS), the structure likely contains a _____ atom if the M+2 peak is approximately 1/3 as tall as the M+ peak

Cl

In Mass Spectrometry (MS), the structure likely contains a _____ atom if the M+2 peak is approximately the same size as the M+ peak

Br

In Mass Spectrometry (MS), a signal at M-15 indicates the loss of a _____ group

Methyl

In Mass Spectrometry (MS), a signal at M-_____ indicates the loss of an ethyl group

29

_____ alkanes have a molecular formula of the form CnH2n+2

Saturated

A compound possessing a pi bond is

unsaturated