Functional groups and mass spectrometry for exam 3 orgo

Alkane

Carbon-carbon single bonds only (C-C).

Alkene

Contains at least one carbon-carbon double bond (C=C).

Alkyne

Contains at least one carbon-carbon triple bond (C≡C).

Alcohol

Contains a hydroxyl group (-OH) bonded to carbon.

Alkyl halide

Contains a halogen (F, Cl, Br, or I) bonded to carbon.

Amine

Contains nitrogen bonded to carbon and/or hydrogen.

Ether

An oxygen bonded to two carbon groups (R-O-R).

Epoxide

A three-membered cyclic ether containing oxygen.

Aldehyde

Contains a terminal carbonyl group (-CHO).

Ketone

Contains a carbonyl (C=O) bonded to two carbon groups.

Carboxylic acid

Contains a carboxyl group (-COOH).

Ester

Contains a carbonyl attached to an oxygen bonded to another carbon (RCOOR).

Aromatic ring

A stable conjugated cyclic ring, commonly represented by benzene.

Carbonyl group

A carbon double-bonded to oxygen (C=O).

Molecular ion peak (M+)

The peak representing the molecule's molecular mass after losing an electron.

Base peak

The tallest peak in a mass spectrum; assigned 100% relative abundance.

Fragmentation

The breaking apart of a molecular ion into smaller ions.

How to identify M+

Find the peak representing the intact molecule's molecular mass.

How to identify the base peak

Find the tallest peak in the mass spectrum.

Why do stable fragments form?

Stable carbocations or resonance-stabilized ions are favored.

Nitrogen rule

An odd nominal molecular mass indicates an odd number of nitrogen atoms.

Chlorine isotope pattern

Chlorine produces M and M+2 peaks in approximately a 3:1 ratio.

Bromine isotope pattern

Bromine produces M and M+2 peaks in approximately a 1:1 ratio.

Why can M+ have an M+2 peak?

Atoms such as chlorine and bromine have abundant heavier isotopes.

Molecular mass vs. fragment mass

M+ represents the intact molecule; fragments represent broken pieces.