华南师范大学：《有机化学》精品课程电子教案（双语版）第八章 现代物理实验方法在有机化学中的应用

附件2 粒大浮 教 案 2003~~2004学年第Ⅰ学期 院(系、所、部)化学与环境学院有机化学研究所 教研室有机化学 课程名称有机化学(双语教学 授课对象化学教育 授课教师杨定乔 职称职务教授 教材名称 Organic Chemistry 2003年09月01日

附件 2 教 案 2003~~ 2004 学年 第 I 学期 院（系、所、部）化学与环境学院有机化学研究所 教 研 室 有机化学 课 程 名 称 有机化学(双语教学) 授 课 对 象 化学教育 授 课 教 师 杨定乔 职 称 职 务 教授 教 材 名 称 Organic Chemistry 2003 年 09 月 01 日

有机化学(双语教学)课程教案 授课题目(教学章节或主题):第八章.现代物理实|授课类型|理论课 验方法在有机化学中的应用( Spectroscopic Methods of Structure Determination 第10周第37-42 授课时间 教学目标或要求:了解电磁波谱的一般概念,包括红外光谱,紫外光谱,核磁共振谱 和质谱的基本理论。掌握并能解析红外光谱,紫外光谱,核磁共振谱。 教学内容(包括基本内容、重点、难点) 基本內容包括了解电磁波谱的—般概念。重点掌握红外光谱,紫外光谱,核磁共振谱 和质谱的基本识谱方法。掌握并能解析红外光谱,紫外光谱,核磁共振谱。 难点是解析氢核磁共振谱谱图。 Infrared Spectroscopy: Background The region of the infrared spectrum which is of greatest interest to organic chemists is the wavelength range 2.5 to 15 micrometers(?. In practice, units proportional to frequency,(wave number in units of cm) rather than wavelength, are commonly used and the region 2.5 to s15 ?corresponds to approximately 4000 to 600 cmi Absorption of radiation in this region by a typical organic molecule results in the excitation of vibrational, rotational and bending modes, while the molecule itself remains in its electronic ground state. Movie files demonstrating vibrational and bending modes for water(H,O) are available by clicking on the icons shown below

有机化学(双语教学) 课程教案 授课题目（教学章节或主题）：第八章．现代物理实 验 方 法 在 有 机 化 学 中 的 应 用 （ Spectroscopic Methods of Structure Determination） 授课类型 理论课 授课时间 第 10 周第 37-42 节 教学目标或要求：了解电磁波谱的一般概念，包括红外光谱，紫外光谱，核磁共振谱 和质谱的基本理论。掌握并能解析红外光谱，紫外光谱，核磁共振谱。 教学内容（包括基本内容、重点、难点）： 基本内容包括了解电磁波谱的一般概念。重点掌握红外光谱，紫外光谱，核磁共振谱 和质谱的基本识谱方法。掌握并能解析红外光谱，紫外光谱，核磁共振谱。 难点是解析氢核磁共振谱谱图。 Infrared Spectroscopy: Background The region of the infrared spectrum which is of greatest interest to organic chemists is the wavelength range 2.5 to 15 micrometers (?. In practice, units proportional to frequency, (wave number in units of cm-1) rather than wavelength, are commonly used and the region 2.5 to 15 ?corresponds to approximately 4000 to 600 cm-1. Absorption of radiation in this region by a typical organic molecule results in the excitation of vibrational, rotational and bending modes, while the molecule itself remains in its electronic ground state. Movie files demonstrating vibrational and bending modes for water (H2O) are available by clicking on the icons shown below:

Symmetric Stretch Asymmetric Stretch Symmetric Bend Molecular asymmetry is a requirement for excitation by infrared radiation and asymmetric stretching or bending transitions are possibles region fully symmetric molecules do not display absorbances in th For the purpose of routine organic structure determination, using a battery of spectroscopic me thods, the most important absorptions in the infrared region are the simple stretching vibrations. For simple systems, these can be approximated by considering the atoms as point masses, linked by a' spring having a force constant k and following Hooke's Law. Using this simple approximation, the equation shown below can be utilized to approximate the characteristic stretching frequency (in cm) of two atoms of masses m and ma, linked by a bond with a force constant k: anyU where ?=m, m, /(m, +m, )(termed the reduced mass), and c is the velocity of light. The stretching vibrations of typical organic molecules tend to fall within distinct regions of the infrared spectrum, as shown below 3700-2500 cm": X-H stretching(X=C, N,O, S) 2300-2000 cm: C-X stretching(X=C or N) 1900-1500 cm": C-X stretching(X=C, N, O) 1300-800 cm: C-X stretching(X=C, N, O) Since most organic molecules have single bonds, the region below 1500 cm" can become quite complex and is often referred to as the fingerprint region: that is, if you are dealing with an unknown molecule which has the same fingerprint in this region, that is considered evidence that the two molecules may be identic Because of the complexity of the region below 1500 cm, in this review, we will focus on functional group stretching bands in the higher frequency region. You should note that for many of these bands, the Ir spectrum may give equivocal structural information; quite often the absence of a band is as informative as the presence of a particular band Use the mENU above to view an IR functional group correlation table, or a sample f common ir absorbance peaks

Symmetric Stretch Asymmetric Stretch Symmetric Bend Molecular asymmetry is a requirement for excitation by infrared radiation and fully symmetric molecules do not display absorbances in this region unless asymmetric stretching or bending transitions are possible. For the purpose of routine organic structure determination, using a battery of spectroscopic methods, the most important absorptions in the infrared region are the simple stretching vibrations. For simple systems, these can be approximated by considering the atoms as point masses, linked by a 'spring' having a force constant k and following Hooke's Law. Using this simple approximation, the equation shown below can be utilized to approximate the characteristic stretching frequency (in cm-1) of two atoms of masses m and m2, linked by a bond with a force constant k: where ?= m1m2/(m1+m2) (termed the 'reduced mass'), and c is the velocity of light. The stretching vibrations of typical organic molecules tend to fall within distinct regions of the infrared spectrum, as shown below: • 3700 - 2500 cm-1 : X-H stretching (X = C, N, O, S) • 2300 - 2000 cm-1 : C X stretching (X = C or N) • 1900 - 1500 cm-1 : C X stretching (X = C, N, O) • 1300 - 800 cm-1 : C-X stretching (X = C, N, O) Since most organic molecules have single bonds, the region below 1500 cm-1 can become quite complex and is often referred to as the 'fingerprint region': that is, if you are dealing with an unknown molecule which has the same 'fingerprint' in this region, that is considered evidence that the two molecules may be identical. Because of the complexity of the region below 1500 cm-1, in this review, we will focus on functional group stretching bands in the higher frequency region. You should note that for many of these bands, the IR spectrum may give equivocal structural information; quite often the absence of a band is as informative as the presence of a particular band. Use the MENU above to view an IR functional group correlation table, or a sample of common IR absorbance peaks

NMR Background Nuclei of isotopes which possess an odd number of protons, an odd number of neutrons, or both, exhibit mechanical spin phenomena which are associated with angular momentum. This angular momentum is characterized by a nuclear spin quantum number, I such that I =1 n, where n is an integer 0, 1, 2, 3. Those nuclei for which i=0 do not possess spin angular momentum and do not exhibit magnetic resonance phenomena. The nuclei of C and 0 fall into this category. Nuclei for which I =/ include H, "F, C, ap and N, while H and"N ave Since atomic nuclei are associated with charge, a spinning nucleus generates a small electric current and has a finite magnetic field associated with it. The magnetic dipole, of the nucleus varies with each element. When a spinning nucleus is ed in a magnetic field, the nuclear magnet experiences a torque which s to align it with the external field. For a nucleus with a spin of /, there are two allowed orientations of the nucleus parallel to the field (low energy) and against the field(high energy). Since the parallel orientation is lower in energy, this state is slightly more populated than the anti-parallel, high energy state.(Figure 1) ① If the oriented nuclei are now irradiated with electromagnetic radiation of the proper frequency, the lower energy state will absorb a quantum of energy and spin-flip to the high energy state. When this spin transition occurs, the nuclei are said to be in resonance with the applied radiation, hence the name nuclear magnetic resonance. The amount of electromagnetic radiation necessary for resonance depends on both

NMR Background Nuclei of isotopes which possess an odd number of protons, an odd number of neutrons, or both, exhibit mechanical spin phenomena which are associated with angular momentum. This angular momentum is characterized by a nuclear spin quantum number, I such that, I = 1/2n, where n is an integer 0,1,2,3...etc. Those nuclei for which I = 0 do not possess spin angular momentum and do not exhibit magnetic resonance phenomena. The nuclei of 1 2C and 1 6O fall into this category. Nuclei for which I = 1/2 include 1H, 1 9F, 1 3C, 31P and 1 5N, while 2H and 1 4N have I = 1. Since atomic nuclei are associated with charge, a spinning nucleus generates a small electric current and has a finite magnetic field associated with it. The magnetic dipole, ? of the nucleus varies with each element. When a spinning nucleus is placed in a magnetic field, the nuclear magnet experiences a torque which tends to align it with the external field. For a nucleus with a spin of 1/2, there are two allowed orientations of the nucleus; parallel to the field (low energy) and against the field (high energy). Since the parallel orientation is lower in energy, this state is slightly more populated than the anti-parallel, high energy state. (Figure 1) If the oriented nuclei are now irradiated with electromagnetic radiation of the proper frequency, the lower energy state will absorb a quantum of energy and spin-flip to the high energy state. When this spin transition occurs, the nuclei are said to be in resonance with the applied radiation, hence the name nuclear magnetic resonance. The amount of electromagnetic radiation necessary for resonance depends on both

the strength of the external magnetic field and on the characteristics of the nucleus being examined. The nucleus of the proton, placed in 14, 100 gauss field, undergoes resonance when irradiated with radiation in the 60 MHz range microwave radiation): higher magnetic fields, such as those common in superconducting magnets, require higher energy radiation and give a correspondingly higher resolution. Use the menu above to move to review sections on other topics in NMR spectros copy. Mass Spectrometry- Background In mass spectrometry, a substance is bombarded with an electron beam having sufficient energy to fragment the molecule. The positive fragments which are produced (cations and radical cations) are accelerated in a vacuum through a magnetic field and are sorted on the basis of mass-to-charge ratio. Since the bulk of the ions produced in the mass spectrometer carry a unit positive charge, the value mye is equivalent to the molecular weight of the fragment. The analysis of mass spectroscopy information involves the re-assembling of fragments, working backwards to generate the original molecule. A schematic representation of a mass spectrometer is shown below Magnetic Field Bends Path of Charged Source G lon Accelerating Collector Exit slit H A very low concentration of sample molecules is allowed to leak into the ionization chamber (which is under a very high vacuum)where they are bombarded by a high-energy electron beam. The molecules fragment and the positive ions produced are accelerated through a charged array into an analyzing tube. The path of the charged molecules is bent by an applied magnetic field. Ions having low mass (low momentum) will be deflected most by this field and will collide with the walls of the analyzer. Likewise, high momentum ions will not be deflected enough and will also collide with the analyzer wall. Ions having the

the strength of the external magnetic field and on the characteristics of the nucleus being examined. The nucleus of the proton, placed in 14,100 gauss field, undergoes resonance when irradiated with radiation in the 60 MHz range (microwave radiation); higher magnetic fields, such as those common in superconducting magnets, require higher energy radiation and give a correspondingly higher resolution. Use the MENU above to move to review sections on other topics in NMR spectroscopy. M a ss S pectrometry - B a ckground In mass spectrometry, a substance is bombarded with an electron beam having sufficient energy to fragment the molecule. The positive fragments which are produced (cations and radical cations) are accelerated in a vacuum through a magnetic field and are sorted on the basis of mass-to-charge ratio. Since the bulk of the ions produced in the mass spectrometer carry a unit positive charge, the value m/e is equivalent to the molecular weight of the fragment. The analysis of mass spectroscopy information involves the re-assembling of fragments, working backwards to generate the original molecule. A schematic representation of a mass spectrometer is shown below: A very low concentration of sample molecules is allowed to leak into the ionization chamber (which is under a very high vacuum) where they are bombarded by a high-energy electron beam. The molecules fragment and the positive ions produced are accelerated through a charged array into an analyzing tube. The path of the charged molecules is bent by an applied magnetic field. Ions having low mass (low momentum) will be deflected most by this field and will collide with the walls of the analyzer. Likewise, high momentum ions will not be deflected enough and will also collide with the analyzer wall. Ions having the

proper mass-to-charge ratio, however, will follow the path of the analyzer, exit through the slit and collide with the Collect or. This generates an electric current, which is then amplified and detected. By varying the strength of the magnetic field, the mass-to-charge ratio which is analyzed can be continuously varied The output of the mass spectrometer shows a plot of relative intensity vs the mass-to-charge ratio (m/e). The most intense peak in the spectrum is termed the base peak and all others are reported relative to it's intensity. The peaks themselves are typically very sharp and are often simply represented as vertical lines The process of fragmentation follows simple and predictable che al pathways and the ions which are formed will reflect the most stable cations and radical cations which that molecule can form. The highest molecular weight peak observed in a spectrum will typically represent the parent molecule, minus an electron, and is termed the molecular ion (M+). Generally, small peaks are also observed above the calculated molecular weight due to the natural isotopic abundance of " C, H, etc. Many molecules with especially labile protons do not display molecular ions: an example of this is alcohols, where the highest molecular weight peak occurs at m/e one less than the molecular ion (m-1). Fragments can be identified by their mass-to-charge ratio, but it is often more informative to identify them by the mass which has been lost. That is, loss of a methy l group will generate a peak at m-15; loss of an ethyl, m-29, etc. The mass spectrum of toluene (methyl benzene) is shown below. The spectrum displays a strong molecular ion at m/e= 92, small m+l and m+2 peaks, a base peak at m/e=91 and an assortment of minor peaks m/e =65 and below. H The molecular ion, again, represents loss of an electron and the peaks above the molecular ion are due to isotopic abundance. The base peak in toluene is due to loss of a hydrogen atom to form the relatively stable benzy l cation This is thought to undergo rearrangement to form the very stable tropylium cation, and this strong peak at m/e=91 is a hallmark of compounds containing a benzyl unit. The minor peak at m/e= 65 represents loss of neutral acetylene

proper mass-to-charge ratio, however, will follow the path of the analyzer, exit through the slit and collide with the Collector. This generates an electric current, which is then amplified and detected. By varying the strength of the magnetic field, the mass-to-charge ratio which is analyzed can be continuously varied. The output of the mass spectrometer shows a plot of relative intensity vs the mass-to-charge ratio (m/e). The most intense peak in the spectrum is termed the base peak and all others are reported relative to it's intensity. The peaks themselves are typically very sharp, and are often simply represented as vertical lines. The process of fragmentation follows simple and predictable chemical pathways and the ions which are formed will reflect the most stable cations and radical cations which that molecule can form. The highest molecular weight peak observed in a spectrum will typically represent the parent molecule, minus an electron, and is termed the molecular ion (M+). Generally, small peaks are also observed above the calculated molecular weight due to the natural isotopic abundance of 1 3C, 2H, etc. Many molecules with especially labile protons do not display molecular ions; an example of this is alcohols, where the highest molecular weight peak occurs at m/e one less than the molecular ion (m-1). Fragments can be identified by their mass-to-charge ratio, but it is often more informative to identify them by the mass which has been lost. That is, loss of a methyl group will generate a peak at m-15; loss of an ethyl, m-29, etc. The mass spectrum of toluene (methyl benzene) is shown below. The spectrum displays a strong molecular ion at m/e = 92, small m+1 and m+2 peaks, a base peak at m/e = 91 and an assortment of minor peaks m/e = 65 and below. The molecular ion, again, represents loss of an electron and the peaks above the molecular ion are due to isotopic abundance. The base peak in toluene is due to loss of a hydrogen atom to form the relatively stable benzyl cation. This is thought to undergo rearrangement to form the very stable tropylium cation, and this strong peak at m/e = 91 is a hallmark of compounds containing a benzyl unit. The minor peak at m/e = 65 represents loss of neutral acetylene

from the tropy lium ion and the minor peaks below this arise from more complex fragmentation. CH Tropylium Ion 教学手段与方法:课堂讲授,幻灯投影谱图 思考题、讨论题、作业:(第601面, Additional problems1419-14.32) 参考资料(含参考书、文献等) 1. Solomons, Organic Chemistry, fifth adition 2. Oxford; Organic Chemistry 3.北京大学,有机化学 4.南京大学,有机化学,(上,下) 5.邢其毅,有机化学,(上,下) 6.有机化合物波谱解析;姚新生主编,中国医药科技出版社 注:1、每项页面大小可自行添减;2一次课为一个教案;3、“重点"、“难点"、“教学手段 与方法”部分要尽量具体;4、授课类型指:理论课、讨论课、实验或实习课、练习或习题 课等

from the tropylium ion and the minor peaks below this arise from more complex fragmentation. 教学手段与方法：课堂讲授，幻灯投影谱图。 思考题、讨论题、作业：(第 601 面，Additional problems;14.19-14.32) 参考资料（含参考书、文献等）： 1. Solomons, Organic Chemistry, fifth adition 2. Oxford; Organic Chemistry 3. 北京大学， 有机化学 4．南京大学， 有机化学，（上，下） 5．邢其毅，有机化学， （上，下） 6．有机化合物波谱解析；姚新生 主编，中国医药科技出版社 注：1、每项页面大小可自行添减；2 一次课为一个教案；3、“重点”、“难点”、“教学手段 与方法”部分要尽量具体；4、授课类型指：理论课、讨论课、实验或实习课、练习或习题 课等