CHY203 - Infrared Spectroscopy lab report

Department of Chemical Engineering Infrared Spectroscopy Student name: Student number: CHY203, Section 02 Group number: 2 March 6, 2013 Instructor: David Naranjit TA: Saif Infrared Spectroscopy Data & Result Sheet 309562516256051911251625601076325162560Known Samples: 1 Molecular Weight: 474.73 g/mol b.p/m.p: 523oC 885825158115Sample Name: Diundecyl Phthalate (DUP): Capillary Film Chemical Formula and Structure: C6H4 [COO (CH2)10CH3]2 Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 3069.94 =CH in aromatic and unsaturated hydrocarbons 3100-3000 (m) 2953.65 -CH3 and –CH- in aliphatic compounds 2990-2850 (m-s) 2855.30 -CH3 and –CH- in aliphatic compounds 2990-2850 (m-s) 1728.11 C=O stretch in ester 1765-1720 (vs) 1487.43 CH3 and CH2 alkanes, alkenes, etc. 1550-1300 1465.83 CH3 and CH2 in aliphatic compounds 1475-1450 (vs) 1465-1440 (vs) 1379.05 CH3 in aliphatic compounds (sym deformation) 1380-1370 (s) 1076325162560Known Samples: 2 : 4724400163830914400159385Sample Name: Polyvinyl Acetate: Cast Film Molecular Weight: 86.09 g/mol Chemical Formula and Structure: (C4H6O2) n Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 2968.12 -CH, -CH2-,-CH3 aliphatic groups 3000-2800 2853.76 -CH3 and -CH2- in aliphatic compounds (CH antisym and sym stretching) 2990-2850 (m-s) 1735.63 C=O stretch ( Esters) 1765-1720 (vs) 1372.88 CH3 in aliphatic compounds (sym deformation) Isopropyl group ( CH3 deformations- two bands) 1380-1370 (s) 1380-1360 (m) 1238.08 C-O-C stretch in Ethers and Esters 1240-1070 (s-vs) 1122.76 C-O-C in aliphatic Ethers (antisym stretch) 1150-1070 (vs) 1022.09 R(alkyl)-C-O stretch in alkyl aryl Ethers 1050-1000 (s) 1076325162560Known Samples: 3 4343400154305895349149860Sample Name: p-Nitrotoluene: Nujol Mull Molecular Weight: 137.13 g/mol Chemical Formula and Structure: C7H7NO2 Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 3025.59 =CH (stretch) in aromatic and unsaturated hydrocarbons 3100-3000 (m) 3005.92 =CH aromatic compound 3100-3000 2850.87 -CH3 and –CH2- in aliphatic compounds 2990-2850 (m-s) 1557.43 -NO2 stretches in aliphatic nitro compounds 1570-1550 (vs) 1468.53 -NO2 stretches in aromatic nitro compounds 1480-1460 (vs) 1454.07 NO2 nitro compounds 1550-1300 1384.64 CH3 sym deformation 1390-1370 (m-s) 698.10 =CH alkenes and aromatic compounds 1000-650 1076325162560Known Samples: 4 8953501638300Sample Name: Polystyrene: Chemical Formula and Structure: (C8H8) n Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 3081.51 =CH (stretch) in aromatic and unsaturated hydrocarbons 3100-3000 (m) 3059.53 =CH in aromatic compound (CH stretch) 3100-3000 (m) 3001.48 =CH (stretch) in aromatic and unsaturated hydrocarbons 3100-3000 (m) 2922.22 -CH3 and –CH2- in aliphatic compounds 2990-2850 (m-s) 1601.02 Benzene ring in aromatic compounds (sharp peak) 1615-1590 (m) 1492.83 Benzene ring in aromatic compounds; sharp band 1515-1485 (m) 1371.72 CH3 (sym deformations) in aliphatic compounds 1380-1370 (s) 1076325162560Known Samples: 5 53911501638303381375163830942974159385 Sample Name: KBr: Caffeine Molecular Weight: 194.19 g/mol b.p/m.p: 178oC Chemical Structure: C8H10N4O2 Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 2953.08 -CH3 and –CH2- in aliphatic compounds 2990-2850 (m-s) 2853.18 CH stretch in C-CH compounds 2970-2850 (s) 2360.07 C=O amides 2400-2000 1736.01 C=O stretch (carbonyl) 1870-1650 (vs, br) 1376.35 CH3 sym deformation 1390-1370 (m-s) 1242.71 C-N (stretch) in aromatic amines 1280-1180 (s) Unknown Samples 5124450149860315277514986031908751498601133475140335Unknown Number: 53 Molecular Weight: 106 g/mol b.p/m.p: 143-144oC Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 3063.96 =CH (stretch) in aromatic and unsaturated hydrocarbons 3100-3000 (m) 3050.08 =CH,=CH2 or –CH=CH- alkenes in aromatic compound 3100-300 1605.07 Benzene ring in aromatic compounds ; sharp peak 1615-1590 (m) 1495.34 Benzene ring in aromatic compounds ; sharp band 1515-1485 (m) 1466.22 CH3 antisym deformation 1470-1440 (m) 1383.87 CH3 sym deformation 1390-1370(m-s) 742.07 Out of plane CH deformations (one or two depending on substitution) 900-650 (s) 667.83 =C-H alkenes and aromatic compounds 1000-650 Identity of Unknown: o-Xylene Chemical Structure: Description of the unknown: o-Xylene is an organic compound which belongs to aromatic hydrocarbons family because of it benzene ring and the two cis methyl substituent with ortho configurations (dimethyl substituent on position 1, 2 on the benzene ring) Unknown Samples 31908751498601133475140335Unknown Number: 1 Absorbance Table Frequency (cm-1) Functional Group Literature (cm-1) 1681.24 C=C stretch in alkenes may be absent for symmetrical reasons 1690-1670 (w) 1659.45 C=C stretch in alkenes; trisubst 1690-1655 (w-s) 1574.21 C=C unsaturated aliphatic compounds 1650-1550 1556.28 CH3 and CH2 in aliphatic compounds 1600-1500 1538.54 CH3 and CH2 in alkanes 1550-1300 1462.94 CH3 antisym deformation 1470-1440 (m) Identity of Unknown: Low-Density Polyethylene Chemical Structure: Discussion How does the energy of a photon with wavenumber 2000cm-1 compare to that of a photon in the ultraviolet range, with a wavelength of 200nm? The energy of photon is directly proportional to the wavenumber and thus inversely proportional to the wave length since wavelength is the inverse of wave number. However, the determination of the energy of the photon depends on the wavelength, the smaller the wavelength, the higher the energy of photon. For example, as the temperature increases, the energy of photon will increases and thus the wavelength of the substance will decreases. Thus, the wave length for wavenumber of 2000cm-1 is 5000 nm which is higher than the wavelength of ultraviolet 200nm. Hence, the energy of photon in the ultraviolet is higher than the energy of photon of wavenumber 2000cm-1. Explain what is meant by the term “group frequency analysis.” Illustrate with an example. Group frequency analysis is a technique that used in infrared spectroscopy experiment to determine the chemical structure for unknown sample by comparing the wavelength of the absorption peaks with the standard frequencies from the tables. For example, o-Xylene ( unknown #53) with given molecular weight of 106g and boiling point of range 143-144 was determined and identified as the absorbance peaks of the sample was analysed using the standard organic frequency table and matched with it chemical structure. How does the vibrational frequency depend on Reduced mass () and Vibrational frequency is defined as the periodic motion of molecular frequency. However, the vibrational frequency is inversely proportional to the reduced mass. Thus, as the mass of the analyte species increases, the vibrational frequency decreases. The force constant (k)? The force constant K is a physical property in which determines the strength of the molecule band. The forces constant; however, is directly proportional to the molecular vibrational frequency. Therefore, the higher vibrational frequency of the sample molecule, the larger force constant will be. In this laboratory, infrared absorption by gases was not considered, even though analysis of gases by infrared is very popular. Describe the apparatus that must be used to obtain infrared absorbance spectra from gases. Gas chromatography -mass spectrometer is a technique that used to determine and identify many different compounds that may be present in the absorbance sample. The apparatus is consistent of two important parts gas chromatograph and mass spectrometer. The gas chromatography has a capillary column which depends mostly on column physical properties such as length, diameter and the thickness of the wire film. As the molecules insides the samples are separated, the molecules will travel from the column to mass spectrometer which will then be ionized molecules. Spectrometer will increase the ionized molecules energy to accelerate and break it to fragments and hence the ionized fragments will be detected and identify using a mass to charge ratio method. Why is such apparatus appropriate for gases but not for condensed phases (solids and liquids)? Gas chromatograph- mass spectrometer is sensitive device that designed for low density substance such as gas molecules .Because of the liquids and solids size and the high density comparing with the gas density, the molecules may be stuck in the capillary column as the sample is analysis which in return will prevent the non-compressible, condensed phase’s substance from passing through the mass chromatography and hence inaccurate determination of the analysis species. What possible application can you suggest for gas-phase infrared analysis in an industrial setting? one possible application can be suggested for gas-phase infrared analysis is develop the apparatus in such way it can determine multiple molecules that happened to travel with same retention time as it passes though the capillary column to increases the efficiency and reduce the amount of time to analysis the substance. State and explain one disadvantage and one advantage of using ATR sampling instead of transmittance. One advantages of using the ATR sampling instead of transmittance T is ease of sampling, the time efficient and limitation of cell path length to the sample to determine a spectrum with high quality used in quantitative analysis methods. ATR sampling techniques is time saving since it require a less time for sample preparation and to analyse and identify a known compounds in IR spectrum. Unlike, the transmittance methods is time consuming in which it requires more time to prepare one sample by using different kinds of techniques (Capillary Film, Cast Film, Nujol Mull and KBr) in order to analyse a known compounds. Hence, ATR sampling is favoured over transmission since it has a high absorptivity peaks comparing to the transmittance in which a detector will be used for measuring IR spectrum with high accuracy. However, one of the disadvantages of using ATR sampling over a transmittance analysis is ATR is a new techniques in which it have less IR spectra analysis tables. Unlike ATR sampling, the IR transmittance has varied widely tables and resources used for analysing the IR spectra. ATR absorption peaks analysis will shift into different wavelength and intensities as IR radiation pass through the sample. Why does the ATR spectrum become very noisy at low wavenumber? Because the ATR spectrum wavelength will shift as the infrared spectroscopy radiation passes through the analysis sample which cause a small variation in the sample refractive index and thus a change in the absorption peaks and intensity. The “infrared cut-off” of a window material used in infrared spectroscopy is the wavenumber at which the window absorbs 50% of the infrared radiation passing through it. What is the approximate infrared cut-off of NaCl (the material used as support for the nujol mull, the capillary film, and the cast film)? The approximate infrared cutoff NaCl that used as supporter for the nujol mull, the capillary film and the cast film is range of 650- 584 cm-1 Graphs of the Known Samples Using Transmittance Analysis: Diundecyl Phthalate (DUP): Polyvinyl Acetate: P-Nitrotoluene: Polystyrene: Transmittance Vs. Wavenumber Absorbance Vs. Wavenumber Nujol: KBr: Graphs of Plastic Samples using ATR Analysis: Polystyrene for ATR High- Density Polyethylene Low- Density Polyethylene polypropylene Graphs of the Unknowns Sample: Unknown #53: o-Xylene Unknown #1: Low-Density Polyethylene References: The 92st edition of the CRC Handbook of Chemistry and Physics, 2011-2012 http://www.hbcpnetbase.com/ Neil, M.J. ( editor) The Merck Index, Merck & CO.,INK , 14th ed., Whitehouse stations, NJ, USA,2006, 11,15,20. Instrumental Methods of Analysis Laboratory Manual, Infrared Spectroscopy, Fourier Transfer Infrared Spectroscopy, Ryerson University 2013, page 24-43 Walzer, K., o-Xylene, Molecular Spectorscopy, 2013, http://en.wikipedia.org/wiki/O-Xylene Peter .U (editor) Molecular Vibrational, Chapman and Hall, 2013 http://en.wikipedia.org/wiki/Molecular_vibration Spectral Database for Organic Compounds SDBS, National Insitute of Advance Industrial Science and Technology, 2013 http://sdbs.riodb.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi Soloway, S., Wavelength Conversions, High Pressure Science http://www.highpressurescience.com/onlinetools/conversion.html G.A, Gas Chromatograph-Mass Spectrometry, Analytical Chemistry,2013 http://en.wikipedia.org/wiki/Gas_chromatography%E2%80%93mass_spectrometry Mirabella M., Attenuated Total Reflectance , Theory and Applications 2013 http://en.wikipedia.org/wiki/Attenuated_total_reflectance www.stfrancis.edu/ns/diab/CRT/.../IR%20vs.%20ATR.ppt