Objective
Introduction Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation. This energy is at a specific resonance frequency which depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms; in practical applications, the frequency is similar to VHF and UHF television broadcasts (60 –1000 MHz). NMR allows the observation of specific quantum mechanical magnetic properties of the atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals, and non-crystalline materials through NMR spectroscopy. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI). All isotopes that contain an odd number of protons of protons and/or of neutrons of neutrons (see Isotope) have an intrinsic magnetic moment and angular momentum, in other words a nonzero spin, while all nuclides with even numbers of both have a total spin of zero. The most commonly studied nuclei are 1H and 13C, although nuclei from isotopes of many other elements (e.g. 2H, 6Li, 10B, 11B, 14N, 15N, 17O, 19F, 23Na, 29Si, 31P, 35Cl, 113Cd, 129Xe, 195Pt) have been studied by high-field NMR spectroscopy as well. A key feature of NMR is that the resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample's nuclei depend on where in the field they are located. Since the resolution of the imaging technique depends on the magnitude of magnetic field gradient, many efforts are made to develop increased field strength, often using superconductors. The effectiveness of NMR can also be improved using hyperpolarization, and/or using two-dimensional, threedimensional and higher-dimensional multi-frequency techniques. The principle of NMR usually involves two sequential steps:
The alignment (polarization) of the magnetic nuclear spins in an applied, constant magnetic field H0. The perturbation of this alignment of the nuclear spins by employing an electro-magnetic, usually radio frequency (RF) pulse. The required perturbing frequency is dependent upon the static magnetic field ( H0) and the nuclei of observation.
The two fields are usually chosen to be perpendicular to each other as this maximizes the NMR signal strength. The resulting response by the total magnetization ( M) of the nuclear spins is the phenomenon that is exploited in NMR spectroscopy and magnetic resonance imaging. Both use intense applied magnetic fields ( H0) in order to achieve dispersion and very high stability to deliverspectral deliverspectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals). NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), NMR), and in several types of magnetometers. of magnetometers. Spectroscopy is the study of the interaction of electromagnetic radiation with matter. Nuclear magnetic resonance spectroscopy is the use of the NMR phenomenon to study physical, chemical,
and biological properties of matter. As a consequence, NMR spectroscopy finds applications in several areas of science. NMR spectroscopy is routinely used by chemists to study chemical structure using simple one-dimensional techniques. Two-dimensional techniques are used to determine the structure of more complicated molecules. These techniques are replacing x-ray crystallography for the determination of protein structure. Time domain NMR spectroscopic techniques are used to probe molecular dynamics in solutions. So lid state NMR spectroscopy is used to determine the molecular structure of solids. Other scientists have developed NMR methods of measuring diffusion coefficients. The versatility of NMR makes it pervasive in the sciences. Scientists and students are discovering that knowledge of the science and technology of NMR is essential for applying, as well as developing, new applications for it. Unfortunately many of the dynamic concepts of NMR spectroscopy are difficult for the novice to understand when static diagrams in hard copy texts are used. The chapters in this hypertext book on NMR are designed in such a way to incorporate both static and dynamic figures with hypertext. This book presents a comprehensive picture of the basic principles necessary to begin using NMR spectroscopy, and it will provide you with an understanding of the principles of NMR from the microscopic, macroscopic, and system perspectives.
Procedure Part A: determination of the spectrum of each component 1. 30mg of aspirin, phenacetin and caffeine was weighted in the different conical vial. 2. About 0.5ml of deuterated chloroform CDCl3 was transferred with clean, dry Pasteur pipet to the sample. 3. The conical vial was swirl to help dissolve the sample. 4. The sample should have completely dissolve after swirling the conical vial and a little more solvent was added, if necessary to dissolve the sample fully. 5. The solution was transferred to the NMR tube using a clean, dry Pasteur pipet. 6. Once the solution has been transferred to the NMR tube, use a clean pipet to add enough deuterated chloroform to bring the total solution height to about 4cm from the bottom. 7. Cap the NMR tube and make sure that the cap is on straight and tight. 8. Invert the NMR tube several times to mix the contents. 9. The sample is ready to record its NMR spectrum. 10. Insert the NMR tube into its holder and adjust the depth by using the gauge provided. 11. For cleaning purpose, transfer the sample into the same conical vial, partially refilled with acetone using a Pasteur pipet, carefully replace the cap and invert the tube several times to rinse it. 12. Remove the acetone and repeat it for 2 times and put the NMR glass tube into an oven for approximately 2 hours. Part B: analysis of the APC tablet 1. Weight approximately 100mg of the tablet. 2. Prepare the sample as described in part A Part C: determining the H NMR spectra 1. The instructor will describe how to operate NMR spectrometer because the controls vary considerably, depending on the manufacturer, model of the instrument, type and software in the computer.
Result 1. CAFFEINE
Spectrum(ppm) 1. 7.444 2. 3.818 3. 3.488 4. 3.335
Type of bond Amide RCONH R2N-CH NC-CH R-C=O-C
splitting singlet Singlet Singlet singlet
Number of bond 1 3 3 2
2. PHENACETIN
SPECTRUM 1. 7.873 2. 7.383 3. 6.889 4. 4.005 5. 2.085 6. 1.380
TYPE OF BOND AMIDE RCONH AROMATIC AROMATIC
splitting Triplet Singlet
Quartet
NUMBER OF BOND 1 2 2
PhOCH RCOCH RH
Double Triplet Singlet
2 4 3
3. ASPIRIN
SPECTRUM 1. 8.200 2. 3. 4. 5.
7.669 7.443 7.281 2.465
TYPE OF BOND AROMATIC
Splitting
Double
NUMBER OF BOND 1
AROMATIC AROMATIC AROMATIC RCOCH
Double Triplet Triplet Singlet
1 1 1 3
TYPE OF BOND AROMATIC AROMATIC AROMATIC AROMATIC RCOCH
Splitting Double Double Triplet Triplet Single
NUMBER OF BOND 1 1 1 1 3
4. UNKNOWN SPECTRUM 1. 8.155 2. 7.672 3. 7.401 4. 7.173 5. 2.390
DISCUSSION In this experiment, we will use NMR to determine the present of photon and it type of bond because NMR is a physical phenomenon in which nuclei in a magnetic field absorb and reemit electromagnetic radiation. This energy is at a specific resonance frequency which depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms; in practical applications, the frequency is similar to VHF and UHF television broadcasts (60 –1000 MHz). NMR allows the observation of specific quantum mechanical magnetic properties of the atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals, and non-crystalline materials through NMR spectroscopy Some error might occur because NMR is very sensitive and can detect very fine structural component. Any contamination can cause false result and wrong analysis. NMR also can detect organic and inorganic, qualitative and quantitative, and versatile. However NMR is very expensive , time consuming and require long time to interpret spectra. In the result, number of spectra depend on the position of photon in the compound which will cause the variety of spectra as result In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of a nucleus relative to a standard. Often the position and number of chemical shifts are diagnostic of the structure of a molecule. Chemical shifts are also used to describe signals in other forms of spectroscopy such as photoemission spectroscopy. Some atomic nuclei possess a magnetic moment (nuclear spin), which gives rise to different energy levels and resonance frequencies in a magnetic field. The total magnetic field experienced by a nucleus includes local magnetic fields induced by currents of electrons in the molecular orbitals (note that electrons have a magnetic moment themselves). The electron distribution of the same 1 13 15 type of nucleus (e.g. H, C, N) usually varies according to the local geometry (binding partners, bond lengths, angles between bonds, ...), and with it the local magnetic field at each nucleus. This is reflected in the spin energy levels (and resonance frequencies). The variations of nuclear magnetic resonance frequencies of the same kind of nucleus, due to variations in the electron distribution, is called the chemical shift. The size of the chemical shift is given with respect to a reference frequency or reference sample (see also chemical shift referencing), usually a molecule with a barely distorted electron distribution.
Conclusion In conclusion, function of NMR and FTIR is same which is to detect the molecule present in the compound. Base on the result, unknown D have similar structure and position as aspirin, so we can conclude that compound D is aspirin.
Reference 1. Principle NMR, http://www.ch.ic.ac.uk/local/organic/nmr_principles.html, 2/6/2013, 11.31am. 2. Chemical shift NMR, http://en.wikipedia.org/wiki/Chemical_shift, 2/6/2013, 11.41am. 3. Nuclear Magnetic resonance, http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance, 2/6/2013, 11.45am. 4. Basic of NMR, http://www.cis.rit.edu/htbooks/nmr/inside.htm, 2/6/2013, 11.55am. 5. Nuclear Magnetic resonance spectroscopy, http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/nmr1.htm, 2/6/2013, 12.05am.
CHM 580 SPECTROCHEMICAL METHOD OF ANALYSIS
EXPERIMENT 2: ANALYSIS OF APC TABLET COMPONENT BY PROTON NMR
NAME
: NORHIDAYU BT AZMI (2011214558)
GROUP MEMBER
: NORHANIS HUSNA MD NADZARUDDIN (2011603436) : KAIRUNISHA ABD RAJAN (2011729747) : HANNISTHASIA JONNEY (2011983935)
INSTRUCTOR
NAME : CIK SITI KARTIKA BT HAMDAN
LECTURER’S NAME
: DR HALILA BT JASMANI
DATE OF EXPERIMENT : 29/4/2013 DATE OF SUBMISSION : 6/6/2013
