ARE YOU MISSING THE INFORMATION THAT NMR SPECTROSCOPY CAN FURNISH?
48
Ν - M - R AT
W O R K
(Nuclear Magnetic Resonance)
VARIAN'S UNIQUE APPLICATIONS LABORATORY CAN SUPPLY THESE MISSING DATA NMR Spectroscopy is α molecular study method that uses a different parameter than any other technique. It can often contribute where other methods are " b l i n d " or inconclusive. Hence NMR may question, confirm or supplement the deductions from your present study methods. The nuclei H 1 , H 2 , F", P31 and B" yield strong NMR signals that "describe" their molecular surroundings. Thus NMR aids in determining correct structural formulas of such substances as steroids, boranes, natural products and products of organic synthesis. It is useful in studies of molecular conformation, electron distribution in molecules, reaction kinetics, and potential energy barriers in molecules. For example, it determines position and extent of deuterium substitution in organic compounds for study of reaction mechanisms. Varian's High Resolution NMR Applications Laboratory has for some time been examining suitably qualified chemical samples on a complimentary exploratory basis. Now in addition Varian will accept a limited number of samples on a fee basis. For $25 Varian will furnish a brief interpretation and an NMR spectrum taken under standard conditions. More complex studies will sometimes be undertaken on an hourly fee basis.
4 8
of a s e r i e s
psi S P E C T R A
INTERPRETATION: The analysis of a mixture of ortho-, pyro-, and poly-phosphoric acids is difficult 1 because these species exist in equilibrium with one another. NMR measurements, however, do not shift the equilibrium. The P3' resonance is affected by its chemical environment to an extent sufficient to resolve completely the signals from orthophosphate (A), pyrophosphate or polyphosphate endgroups (B), and middle-groups of polyphosphates (C). The areas
AT 14,100
GAUSS
under the curves are proportional to the number of phosphorus atoms in each environment. The mixture which gave the spectrum shown below contained an excess of PzOs over the amount required for the formation of H3PO4. The predominant species is pyrophosphoric acid (N = 0), with a small amount of H3PO4 and a larger amount of phosphorus present in polyphosphorîc acids.
Write Mr. L F. Johnson for full information on Varian's laboratory services. Current literature on Varian's NMR and BPR spectrometers will also be furnished, if requested.
V A R I A N
associates
INSTRUMENT PALO
ALTO
4,
DIVISION CALIFORNIA
For further information, circle number 57 A on Readers' Service Card, page 89 A
VOL. 30, NO. 6, JUNE 1958
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57 A
