Spectroscopy Flashcards
Uv spec is most useful for detecting ?
Conjugated alkenes
Mass spectroscopy results in the separation of fragments according to ?
Mass to charge ratio
How does water effect alcohols with the NMR spectra
The hydroxyl exchanges protons with the water , preventing it from coupling
The isotope c12 is not useful for NMR because ?
It has no magnetic moment. Only elements with an odd number of electrons can have magnetic moments
Chemical shifts of a proton for these functional groups in the NMR spectrum
Alkyl
Aromatic
Aldehyde
Carboxyl
1ppm
7ppm
9.5ppm
11ppm
Ir spec is most useful for distinguishing ?
Double and triple bonds
The process of measuring the frequencies of electromagnetic radiation absorbed by a molecule
Spectroscopy
IR spectroscopy measures?
Molecular vibrations
Stretching bonding rotation
The useful numbers of infrared light occur in frequency range from 400 to 4000 cm called ?
Wave numbers
Fingerprint region ?
Between 400 and 1500 cm which is unique to a molecule , complex vibrations
In order for IR light to be absorbed , the vibration of the molecule must result in ?
A change in the bond dipole moment
Ex o2 and br2 do not
Characteristic absorption frequencies ?
Single bonds
Double bonds
Triple bonds
1200
1600
2200
Functionalgroup/1700-1750/3100-3500
Alcohol
Aldehyde/ketone
Carboxylic acid
Amine
No Yes (broad)
Yes No
Yes. Broad peak
No. Sharp peak
Gives areas of absorption the appearance of valleys on the spectrum.
Percent transmission (the inverse of absorption) vs frequency
Nuclei whose magnetic moments are aligned with the field vs against the field (NMR)
Alpha (lower energy )
Beta (higher energy )