ochem week 8 part 2

Integration

The area under an NMR peak, which indicates the number of hydrogen atoms associated with that signal.

Homotopic

Hydrogens that share the same electronic environment and consequently have the same chemical shift in NMR.

Downfield

In NMR, the direction of increasing chemical shift; signals that are farther downfield indicate greater deshielding due to electronegative atoms or double bonds.

Vinylic Hydrogen

A hydrogen atom directly attached to a carbon that is involved in a double bond.

Allylic Hydrogen

A hydrogen atom attached to a carbon that is adjacent to a carbon involved in a double bond.

Chemical Shift

The resonant frequency of a nucleus relative to a standard in a magnetic field, influencing how the NMR peaks appear.

Peak Splitting

The phenomenon in NMR where a peak is divided into multiple sub-peaks due to the presence of neighboring hydrogen atoms.

Singlet

An NMR signal with no splitting, indicative of a hydrogen atom with no neighbors.

Doublet

An NMR signal split into two peaks, typical for a hydrogen atom with one neighboring hydrogen atom.

Triplet

An NMR signal split into three peaks, indicative of a hydrogen atom with two neighboring hydrogen atoms.

Quartet

An NMR signal split into four peaks, indicative of a hydrogen atom with three neighboring hydrogen atoms.

J Value

The coupling constant in NMR that quantifies the interaction between coupled nuclei.

Reference Peak

In NMR, a peak that serves as a reference point for all other chemical shift measurements.

Equivalent Hydrogens

Hydrogens that are in the same electronic environment and thus have the same chemical shift.

Multiplet

An NMR signal that shows complex splitting due to multiple neighboring hydrogen atoms.

Aromatic Region

The area in an NMR spectrum where signals for hydrogen atoms on an aromatic ring typically appear, usually between 6.5 and 8 ppm.

Alkene Region

The area in an NMR spectrum where vinyl or double-bonded hydrogen signals typically appear, usually around 4.5 to 6 ppm.

Coupling Constant

A measure of the interaction between nuclear spins that leads to splitting of NMR peaks.

Downfield Shifts

Occur when hydrogens are deshielded; often due to electronegative atoms or double bonds nearby.

Electronegative Atoms effect on NMR

Electronegative atoms nearby can cause a downfield shift in the NMR peaks for hydrogens.