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1、第02章 烷烃1现在学习的是第1页，共59页烷烃的构造异构(1)C2H6(1)C3H8(1)CH4(1)直链烷烃(正构烷烃)Straight-chain(normal)alkaneC4H10(2)支链烷烃Branched-chain alkane构造异构(Constitutional isomerism)分子中的原子因连接次序和方式不同而产生的异构2现在学习的是第2页，共59页烷烃的构造异构(2)C5H12(3)构造异构体(Consititutional isomers)3现在学习的是第3页，共59页烷烃构造异构(3)分子式异构体数目分子式异构体数目CH41C7H169C2H61C8H1818
2、C3H81C9H2035C4H102C10H2275C5H123C20H42366,319C6H145C30H624,111,846,763The number of CnH2n+2(General formula)isomers has been calculated for values of n from 1 to 400 and the comment made that the number of isomers of C167H336 exceeds the number of particles in the known universe(1080).Francis Carey:
3、Organic Chemistry,Chapter 2,4th ed4现在学习的是第4页，共59页构造异构的种类骨架异构官能团异构位置异构5现在学习的是第5页，共59页烷烃的同系列同系列(Homologous series)在组成上相差一个或几个CH2，且结构和性质相似的一系列化合物 同系物(Homolog)构成同系列化合物(CH2为系差)同系物非同系物同系物6现在学习的是第6页，共59页烷烃分子中不同环境的碳伯Primary(1)仲Secondary(2)叔Tertiary(3)季Quaternary(4)7现在学习的是第7页，共59页烷烃分子中不同环境的氢伯氢叔氢仲氢8现在学习的是第8页，
4、共59页烷烃的命名概述前缀母体后缀化合物系统名称的构成IUPAC(国际纯粹与应用化学联合会)International Union of Pure and Applied Chemistry9现在学习的是第9页，共59页烷烃的命名直链烷烃1Methane11Undecane21Henicosane31Hentriacontane2Ethane12Dodecane22Docosane32Dotriacontane3Propane13Tridecane23Tricosane33Tritriacontane4Butane14tetradecane24Tetracosane40Tetracontane
5、5Pentane15Pentadecane25Pentacosane50Pentacontane6Hexane16Hexadecane26Hexacosane60Hexacontane7Heptane17Heptadecane27Heptacosane70Heptacontane8Octane18Octadecane28Octacosane80Octacontane9Nonane19Nonadecane29Nonacosane90Nonacontane10Decane20Icosane30Triacontane100Hectane甲烷(1)，乙烷(2)，丙烷(3)，丁烷(4)，戊烷(5)己烷(
6、6)，庚烷(7)，辛烷(8)，壬烷(9)，癸烷(10)十一烷(11)，十二烷(12)，十三烷(13)，十四烷(14)10现在学习的是第10页，共59页烷烃的命名直链烷基烷基(Alkyl)名称缩写CH3甲基(Methyl)MeCH2CH3乙基(Ethyl)EtCH2CH2CH3丙基(Propyl)PrCH2CH2CH2CH3丁基(Butyl)BuCH2CH2CH2CH2CH3戊基(Pentyl)11现在学习的是第11页，共59页烷烃的命名支链烷烃2-甲基戊烷新己烷新戊烷异戊烷异丁烷12现在学习的是第12页，共59页烷烃的命名支链烷基1,2-二甲基丙基异丙基(Isopropyl)异丁基(Isobu
7、tyl)仲丁基(sec-Butyl)叔丁基(tert-Butyl)13现在学习的是第13页，共59页烷烃的命名复杂烷烃(1)(3-甲基己烷)(2-甲基-3-乙基己烷)(3-甲基-4-乙基庚烷)(4,7-二甲基-3-乙基壬烷)14现在学习的是第14页，共59页2,3-二甲基-6-(2-甲基丙基)癸烷2-甲基-5-(1,2-二甲基丙基)壬烷烷烃的命名复杂烷烃(2)(1,2-二甲基丙基)15现在学习的是第15页，共59页烷烃的命名复杂烷烃(3)3-甲基-5-乙基-4-叔丁基庚烷2,3,5-三甲基-4-丙基庚烷16现在学习的是第16页，共59页乙烷的结构键能CC 376 kJ/molCH 420 kJ
8、/mol17现在学习的是第17页，共59页乙烷的构象交叉式构象(Conformation)分子中的原子或取代基绕-键旋转在空间产生的不同排列方式交叉式构象18现在学习的是第18页，共59页乙烷的构象重叠式重叠式构象19现在学习的是第19页，共59页构象与能量的关系20现在学习的是第20页，共59页丁烷的构象对位交叉式(Anti)部分重叠式(Eclipsed)邻位交叉式(Gauche)全部重叠式(Eclipsed)21现在学习的是第21页，共59页丁烷构象能量图22现在学习的是第22页，共59页烷烃的物理性质熔点：物质固液两相平衡时的温度。沸点：物质的饱和蒸气压等于外界压力时的温度。溶解度：两种
9、以上的物质能够均匀混合形成一相时的最大浓度。物理性质与分子间力存在着直接的关系23现在学习的是第23页，共59页分子间力取向力偶极分子之间的作用力(Dipole-dipole force)24现在学习的是第24页，共59页分子间力诱导力极性分子非极性分子极性分子和非极性分子间的作用(Induced dipole force)25现在学习的是第25页，共59页分子间力色散力氦原子的极化非极性分子间的作用(London dispersion force)26现在学习的是第26页，共59页直链和支链烷烃的沸点27现在学习的是第27页，共59页烷烃分子的大小对沸点的影响28现在学习的是第28页，共59
10、页烷烃分子的形状对熔点和沸点的影响29现在学习的是第29页，共59页戊烷三个异构体30现在学习的是第30页，共59页烷烃的溶解度对任何物理或化学过程：G：吉布斯函数变H：焓T：温度S：熵（混乱度）在等温等压条件下若 G 0；若溶剂和溶质具有相似的分子结构，则H0，那么 G 0，溶解过程可以自发进行相似相溶(Like dissolves like)。A familiar physical property of alkanes is contained in the adage“oil and water dont mix.”31现在学习的是第31页，共59页烷烃的化学性质氧化可用烷烃的燃烧热判
11、断烷烃的相对稳定性32现在学习的是第32页，共59页烷烃的反应异构化可用化合物的生成热判断化合物的稳定性33现在学习的是第33页，共59页烷烃的反应裂化热解：有机物在高温下的分解 裂化：烷烃的热解称为裂化（500600C）催化裂化：在催化剂存在下进行的裂化 裂解：在700以上进行的裂化 34现在学习的是第34页，共59页烷烃的反应甲烷的氯代取代反应分子中的原子或原子团被其它原子或原子团代替的反应35现在学习的是第35页，共59页烷烃的氯代不同氢的活性不同环境的氢有不同的活性烷烃氯代时不同氢的活性比为：3氢 2氢 1氢 5 4 1h43%57%64%36%h36现在学习的是第36页，共59页烷烃
12、的溴代反应的活性：Cl2 Br2反应的选择性：Br2 Cl237现在学习的是第37页，共59页反应机理共价键的断裂与生成均裂自由基(中间体)异裂离子(中间体)自由基反应离子型反应反应机理反应从反应物开始经由中间体到生成产物的全过程38现在学习的是第38页，共59页甲烷氯代的机理39现在学习的是第39页，共59页反应进程甲烷和氯自由基的反应40现在学习的是第40页，共59页反应机理甲基自由基和氯原子的反应41现在学习的是第41页，共59页反应进程甲基自由基和氯的反应42现在学习的是第42页，共59页甲烷氯代的总反应热盖斯定律一个化学反应的反应热只与反应的起始状态有关而与过程无关43现在学习的是第
13、43页，共59页自由基的消失44现在学习的是第44页，共59页自由基反应的三个阶段链引发链增长链中止45现在学习的是第45页，共59页甲烷氯代和溴代的比较一个化学反应进行的程度取决于动力学和热力学两个因素46现在学习的是第46页，共59页共价键的解离能与自由基反应活性的关系438 kJ mole1420 kJ mole1390 kJ mole1401 kJ mole147现在学习的是第47页，共59页自由基的稳定性三类氢的活泼性和溴的选择性48现在学习的是第48页，共59页Introduction to Alkanes(1)Alkanes have the general molecular
14、formula CnH2n+2.The simplest one,methane(CH4),is also the most abundant.Large amounts are present in our atmosphere,in the ground,and in the oceans.Methane has been found on Jupiter,Saturn,Uranus,Neptune,and Pluto,and even on Halleys Comet.Ethane(C2H6:CH3CH3)and propane(C3H8:CH3CH2CH3)are second and
15、 third,respectively,to methane in many ways.Ethane is the alkane next to methane in structural simplicity,followed by propane.Ethane(10%)is the second and propane(5%)the third most abundant component of natural gas,which is 75%methane.Francis Carey:Organic Chemistry,Chapter 2,4th ed49现在学习的是第49页，共59页
16、The characteristic odor of natural gas we use for heating our homes and cooking comes from trace amounts of unpleasant-smelling sulfur-containing compounds such as ethanethiol that are deliberately added to it in order to warn us of potentially dangerous leaks.Natural gas is colorless and nearly odo
17、rless,as are methane,ethane,and propane.Introduction to Alkanes(2)Francis Carey:Organic Chemistry,Chapter 2,4th edCompoundMethaneEthanePropaneFormulaCH4CH3CH3CH3CH2CH3Boiling point160C89C42C50现在学习的是第50页，共59页Introduction to Alkanes(3)Methane is the lowest boiling alkane,followed by ethane,then propan
18、e.This will generally be true as we proceed to look at other alkanes;as the number of carbon atoms increases,so does the boiling point.All the alkanes with four carbons or less are gases at room temperature and atmospheric pressure.With the highest boiling point of the three,propane is the easiest o
19、ne to liquefy.We are all familiar with“propane tanks.”These are steel containers in which a propane-rich mixture of hydrocarbons called liquefied petroleum gas(LPG)is maintained in a liquid state under high pressure as a convenient clean-burning fuel.Francis Carey:Organic Chemistry,Chapter 2,4th ed5
20、1现在学习的是第51页，共59页Introduction to Alkanes(4)“Butane”lighters contain about 5%n-butane and 95%isobutane in a sealed container.The pressure produced by the two compounds(about 3 atm)is enough to keep them in the liquid state until opening a small valve emits a fine stream of the vaporized mixture across
21、 a spark which ignites it.Francis Carey:Organic Chemistry,Chapter 2,4th edCompoundButaneIsobutaneFormulaCH4CH3CH3CH3CH3CH3CH(CH3)2Boiling point0.4C10.2CMelting point139C160.9C52现在学习的是第52页，共59页Introduction to Alkanes(5)Much of the communication between insects involves chemical messengers called pher
22、omones(信息素).A species of cockroach secretes a substance from its mandibular(上颚的)glands that alerts other cockroaches to its presence and causes them to congregate.One of the principal components of this aggregation pheromone is undecane.Francis Carey:Organic Chemistry,Chapter 2,4th edUndecane CH3(CH
23、2)9CH353现在学习的是第53页，共59页PetroleumFrancis Carey:Organic Chemistry,Chapter 2,4th edPetroleum is a liquid mixture containing hundreds of substances,including approximately 150 hydrocarbons,roughly half of which are alkanes or cycloalkanes.The first oil well,drilled in Titusville,Pennsylvania,by Edwin Dr
24、ake in 1859,provided“rock oil,”as it was then called,on a large scale.This was quickly followed by the development of a process to“refine”it so as to produce kerosene.Other oil fields were discovered,and uses for other petroleum products were foundilluminating gas lit city streets,and oil heated hom
25、es and powered locomotives.There were oil refineries long before there were automobiles.By the time the first Model T rolled off Henry Fords assembly line in 1908,John D.Rockefellers Standard Oil holdings had already made him one of the half-dozen wealthiest people in the world.54现在学习的是第54页，共59页Meth
26、ane and the Biosphere(1)Francis Carey:Organic Chemistry,Chapter 2,4th edMethane is one of literally millions of compounds in the carbon cycle,but one of the most abundant.It is formed when carbon-containing compounds decompose in the absence of air(anaerobic conditions).The organisms that bring this
27、 about are called methanoarchaea(甲烷古菌).Cells can be divided into three types:archaea(古菌),bacteria(细 菌),and eukarya(真核生物).Methanoarchaea are one kind of archaea and may rank among the oldest living things on earth.They can convert a number of carbon-containing compounds,including carbon dioxide and a
28、cetic acid,to methane.*The biosphere is the part of the earth where life is;it includes the surface,the oceans,and the lower atmosphere.55现在学习的是第55页，共59页Methane and the Biosphere(2)Francis Carey:Organic Chemistry,Chapter 2,4th edVirtually anywhere water contacts organic matter in the absence of air
29、is a suitable place for methanoarchaea to thriveat the bottom of ponds,bogs,and rice fields,for example.Marsh gas(swamp gas)is mostly methane.Methanoarchaea live inside termites and grass-eating animals.One source quotes 20 L/day as the methane output of a large cow.The scale on which methanoarchaea
30、 churn out methane,estimated to be 10111012 lb/year,is enormous.About 10%of this amount makes its way into the atmosphere,but most of the rest simply ends up completing the carbon cycle.It exits the anaerobic environment where it was formed and enters the aerobic world where it is eventually convert
31、ed to carbon dioxide by a variety of processes.56现在学习的是第56页，共59页Methane and the Biosphere(3)Francis Carey:Organic Chemistry,Chapter 2,4th edWhen we consider sources of methane we have to add“old”methane,methane that was formed millions of years ago but became trapped beneath the earths surface,to th
32、e“new”methane just described.Firedamp,an explosion hazard to miners,occurs in layers of coal and is mostly methane.Petroleum deposits,formed by microbial decomposition of plant material under anaerobic conditions,are always accompanied by pockets of natural gas,which is mostly methane.57现在学习的是第57页，共
33、59页Methane and the Biosphere(4)Francis Carey:Organic Chemistry,Chapter 2,4th edAn interesting thing happens when trapped methane leaks from sites under the deep ocean floor.If the pressure is high enough(50 atm)and the water cold enough(4C),the methane doesnt simply bubble to the surface.Individual
34、methane molecules become trapped inside clusters of 618 water molecules forming methane clathrates or methane hydrates.Aggregates of these clathrates stay at the bottom of the ocean in what looks like a lump of dirty ice.Ice that burns.Far from being mere curiosities,methane clathrates are potential
35、 sources of energy on a scale greater than that of all known oil reserves combined.At present,it is not economically practical to extract the methane,however.58现在学习的是第58页，共59页Methane and the Biosphere(5)Francis Carey:Organic Chemistry,Chapter 2,4th edMethane clathrates have received recent attention
36、 from a different segment of the scientific community.While diving in the Gulf of Mexico in 1997,a research team of biologists and environmental scientists were surprised to find a new species of worm grazing on the mound of a methane clathrate.What were these worms feeding on?Methane?Bacteria that live on the methane?A host of questions having to do with deep-ocean ecosystems suddenly emerged.Stay tuned.59现在学习的是第59页，共59页