Organic Chemistry II: Infrared Spectroscopy and Mass Spectrometry

These flashcards cover key concepts from Organic Chemistry II related to Infrared Spectroscopy and Mass Spectrometry, focusing on definitions, techniques, and theoretical principles.

Infrared Spectroscopy

A technique that involves the interaction of matter with infrared radiation to study the vibrational transitions of molecules.

Mass Spectrometry

An analytical technique used to measure the mass-to-charge ratio of ions, used for identifying molecular composition.

Elemental Analysis

The process of determining the elemental composition of a substance.

Empirical Formula

A formula that shows the simplest whole-number ratio of atoms in a compound.

Molecular Formula

A formula that indicates the actual number of atoms of each element in a molecule.

Mass Spectrometer

An instrument used to analyze the mass of charged particles.

Electromagnetic Radiation

Energy propagated through space which exhibits wave-like behavior, encompassing various forms including light.

Wavelength

The distance between consecutive peaks of a wave, inversely proportional to frequency.

Frequency

The number of waves that pass a given point per second, directly proportional to energy.

Transmittance

The fraction of incident light that passes through a sample.

Spectroscopy

The study of the interaction between matter and electromagnetic radiation.

Nuclear Magnetic Resonance Spectroscopy (NMR)

A technique that exploits the magnetic properties of certain atomic nuclei to infer molecular structure.

Magnetic Resonance Imaging (MRI)

A medical imaging technique based on NMR to visualize internal structures of the body.

X-Ray Crystallography

A technique used to determine the atomic and molecular structure of a crystal by scattering X-ray beams off the atoms.

Degrees of Unsaturation

The number of rings and pi bonds present in a molecule.

Rule of 13

A method used to deduce the molecular formula from the molecular mass.

Vibrational Spectroscopy

A spectroscopic technique used to obtain information about the vibrations of the atoms in a molecule.

Functional Groups

Specific groups of atoms within molecules that determine characteristic chemical reactions.

Symmetric Stretching

A molecular vibration where atoms move equally toward and away from the center.

Asymmetric Stretching

A molecular vibration where one atom moves toward the center while another moves away.

Scissoring

A bending vibration in which atoms move in a plane toward and away from each other.

Twisting

A bending vibration in which the bonds rotate in a nonlinear fashion.

Rocking

A bending vibration where atoms move back and forth in a single plane.

Wagging

A bending vibration involving a non-planar motion of atoms.

Wavenumber

The spatial frequency of a wave, commonly used in spectroscopy (measured in cm^-1).

C-H stretching

A vibrational mode associated with the stretching of carbon-hydrogen bonds.

O-H stretch

A vibrational mode associated with the stretching of oxygen-hydrogen bonds, typically exhibits a broad absorption.

Carbonyl Group (C=O)

A functional group characterized by a carbon atom double-bonded to an oxygen atom.

Dipole Moment

A measure of the separation of positive and negative charges in a molecule.

Hydrogen Bonding

A weak attraction between a hydrogen atom bonded to an electronegative atom and another electronegative atom.

Signal Intensity

The strength of the signal in spectroscopy, varying based on functional groups.

Broad Signal

A spectral signal that spans a wide range of wavelengths, often due to hydrogen bonding.

N-H stretching

A vibrational mode associated with nitrogen-hydrogen bonds, observed in amines.

O-H stretch for alcohols

The absorption of IR radiation by the O-H bond in alcohols, which can lead to broad signals.

Alkene C-H stretch

The characteristic stretching frequency associated with C-H bonds in alkenes.

Conjugated Systems

A system of connected p-orbitals with delocalized electrons in molecules.

IR Spectra

The graphical representation of the infrared absorption of a molecule, showing wavenumber vs. transmittance.

Absorption Frequency

The specific frequency at which a molecule absorbs infrared radiation.

Functional Group Analysis

The identification of chemical groups responsible for specific properties and reactions of compounds.

Diagnostic Region

A specific region of an IR spectrum that is particularly useful for identifying functional groups.

IR Spectrum Interpretation

The process of analyzing IR spectra to deduce the presence and type of functional groups in a compound.

Amines

Organic compounds derived from ammonia, containing one or more alkyl or aryl groups.

Carboxylic Acids

Organic acids characterized by the presence of a carboxyl group (-COOH).

Ketones

Organic compounds containing a carbonyl group (C=O) with two carbon substituents.

Aldehydes

Organic compounds containing a carbonyl group (C=O) with at least one hydrogen substituent.

Tips for Analyzing IR Spectra

Guidelines for identifying functional groups in IR spectra based on absorbance patterns.

Secondary Amines

Amines where nitrogen is bonded to two carbon groups.

Primary Amines

Amines where nitrogen is bonded to one carbon group and two hydrogen atoms.

Quantized Energy Levels

The discrete energy levels associated with molecular vibrations.

Harmonic Oscillator

A model used to describe the behavior of bonds as springs that can stretch and compress.

Evaporation

The process by which molecules escape from a liquid to become vapor.

Alcohols

Organic compounds containing one or more hydroxyl (-OH) functional groups.

Morse Curve

A graphical representation of the potential energy of a diatomic molecule as a function of bond distance.

Reduced Mass

The effective mass used in calculations involving two-body systems.

Compound Elucidation Steps

The systematic approach to determining the molecular structure of a compound.