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Because many solvents also have protons present, their use in obtaining NMR spectra is problematic. The signal due to the protons in a typical organic solvent would be so large that it would swamp any signal due to the sample you want to measure - sort of like trying to see a tiny flashlight in broad daylight outdoors. In order to remedy this problem, one could choose solvents which do not have protons such as CS 2 size 12{ ital "CS" rSub { size 8{2} } } {} or CCl 4 size 12{ ital "CCl" rSub { size 8{4} } } {} ; however, these are not suitable solvents for modern FT spectrometers. A better solution is to use solvents in which the protons have been replaced by deuterium. Such solvents, known as deuterated solvents, have very similar properties to their proton-analogues. Thus deuterated benzene is very similar to normal benzene. While deuterium does have a spin (spin = 1), the frequency at which the deuterium nucleus resonates in a magnetic field is sufficiently different from that of protons so that its presence does not interfere with the detection of proton signals. In reality, not all protons of a solvent are replaced in deuterated solvents such that a residual peak due to the presence of a small quantity of protons can usually be observed. This peak usually serves as a good reference point for determining the chemical shifts of peaks in the sample since the peak locations of common deuterated solvents are well known. One can also add a small amount of TMS [tetramethylsilene, Si ( CH 3 ) 4 size 12{ ital "Si" \( ital "CH" rSub { size 8{3} } \) rSub { size 8{4} } } {} ] to the sample and use its peak to serve as a reference peak as well.

Table 2. Some commonly used deuterated solvents.

d-chloroform CDCl 3 size 12{ ital "CDCl" rSub { size 8{3} } } {}
d 6 size 12{d rSub { size 8{6} } } {} -benzene C 6 D 6 size 12{C rSub { size 8{6} } D rSub { size 8{6} } } {}
d 3 size 12{d rSub { size 8{3} } } {} -acetonitrile CD 3 CN size 12{ ital "CD" rSub { size 8{3} } ital "CN"} {}
d 6 size 12{d rSub { size 8{6} } } {} -acetone CD 3 C ( = O ) CD 3 size 12{ ital "CD" rSub { size 8{3} } C \( =O \) ital "CD" rSub { size 8{3} } } {}
d 4 size 12{d rSub { size 8{4} } } {} -methanol CD 3 OD size 12{ ital "CD" rSub { size 8{3} } ital "OD"} {}
d 8 size 12{d rSub { size 8{8} } } {} -toluene C 6 D 5 CD 3 size 12{C rSub { size 8{6} } D rSub { size 8{5} } ital "CD" rSub { size 8{3} } } {}
d 2 size 12{d rSub { size 8{2} } } {} -dichloromethane CD 2 Cl 2 size 12{ ital "CD" rSub { size 8{2} } ital "Cl" rSub { size 8{2} } } {}
deuterated water D 2 O size 12{D rSub { size 8{2} } O} {}
In order to obtain really high field strengths, special magnets have been built of materials that are kept at liquid helium temperatures such that they become superconducting. Typically field strengths of 200, 300, 400, and 500 MHz are commonly employed. Instruments are even being built with field strengths as high as 900 MHz!!! The choice of field strength depends upon the sample and bigger is usually, but not always, better.

Because the field strengths are so high, it is potentially dangerous for persons with pacemakers to enter into the fringe field region of these magnets. The magnets will also erase the magnetic information stored on IDs and credit cards. The stronger magnets have been known to pull heavy tools up into them if someone with tools walks too close to the magnet. This often causes severe damage to the magnet.

In this set of exercises, we are going to concentrate on 1 H size 12{ {} rSup { size 8{1} } H} {} NMR spectroscopy since it is the most widely used and simplest of the NMR-active nuclei to discuss.

Chemical shift

Since the effect being measured involves the measurement of spin states of a nucleus, the values of Δ size 12{Δ} {} E will be affected by the local magnetic field of a nucleus being examined.

The local magnetic field is, in turn, affected by the chemical environment of the nucleus. Δ size 12{Δ} {} E thus becomes a measure of the chemical environment of the nucleus. Hydrogen atoms bonded to sp 3 size 12{ ital "sp" rSup { size 8{3} } } {} carbon atoms are found in different regions of the NMR spectrum from hydrogen atoms attached to alkene sp 2 size 12{ ital "sp" rSup { size 8{2} } } {} carbon atoms, alkyne sp carbon atoms, and aromatic sp 2 size 12{ ital "sp" rSup { size 8{2} } } {} carbon atoms, oxygen, nitrogen, metals, etc.

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Chem 215 spring08. OpenStax CNX. Mar 21, 2008 Download for free at http://cnx.org/content/col10496/1.8
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