《有机化学英文chapter2学习教案.pptx》由会员分享，可在线阅读，更多相关《有机化学英文chapter2学习教案.pptx（70页珍藏版）》请在taowenge.com淘文阁网|工程机械CAD图纸|机械工程制图|CAD装配图下载|SolidWorks_CaTia_CAD_UG_PROE_设计图分享下载上搜索。
1、会计学1有机化学有机化学(yu j hu xu)英文英文chapter2第一页，共70页。AlkanesandCycloalkanesChapter 2Chapter 2第1页/共70页第二页，共70页。Structuren nHydrocarbon:a compound composed only of carbon and hydrogenn nSaturated hydrocarbon:a hydrocarbon containing only single bondsn nAlkane:a saturated hydrocarbon whose carbons are arranged
2、 in an open chainn nAliphatic hydrocarbon:another name for an alkane第2页/共70页第三页，共70页。Hydrocarbons第3页/共70页第四页，共70页。Structuren nShapen ntetrahedral about carbonn nall bond angles are approximately 109.5第4页/共70页第五页，共70页。Drawing Alkanesn nLine-angle formulasn nan abbreviated way to draw structural formu
3、lasn neach vertex and line ending represents a carbon第5页/共70页第六页，共70页。Constitutional Isomerismn nConstitutional isomers:compounds with the same molecular formula but a different connectivity of their atomsn nexample:C4H10第6页/共70页第七页，共70页。Constitutional Isomerismn ndo these formulas represent constit
4、utional isomers?n nfind the longest carbon chainn nnumber each chain from the end nearest the first branch n ncompare chain lengths as well the identity and location of branches第7页/共70页第八页，共70页。Constitutional IsomerismWorld populationWorld populationis aboutis about6,000,000,0006,000,000,000第8页/共70页
5、第九页，共70页。Nomenclature-IUPACn nSuffix-ane specifies an alkanen nPrefix tells the number of carbon atoms第9页/共70页第十页，共70页。Nomenclature-IUPACn nParent name:the longest carbon chainn nSubstituent:a group bonded to the parent chain n nalkyl group:a substituent derived by removal of a hydrogen from an alka
6、ne;given the symbol R-第10页/共70页第十一页，共70页。Nomenclature-IUPAC1.The name of a saturated hydrocarbon with an unbranched chain consists of a prefix and suffix2.The parent chain is the longest chain of carbon atoms3.Each substituent is given a name and a number4.If there is one substituent,number the chai
7、n from the end that gives it the lower number第11页/共70页第十二页，共70页。Nomenclature-IUPAC5.If there are two or more identical substituents,number the chain from the end that gives the lower number to the substituent encountered firstn nindicate the number of times the substituent appears by a prefix di-,tr
8、i-,tetra-,etc.n nuse commas to separate position numbers第12页/共70页第十三页，共70页。Nomenclature-IUPAC6.If there are two or more different substituents,n nlist them in alphabetical ordern nnumber from the end of the chain that gives the substituent encountered first the lower number第13页/共70页第十四页，共70页。Nomencl
9、ature-IUPAC7.The prefixes di-,tri-,tetra-,etc.are not included in alphabetizationn nalphabetize the names of substituents first and then insert these prefixes第14页/共70页第十五页，共70页。Nomenclature-IUPACn nAlkyl groups第15页/共70页第十六页，共70页。Nomenclature-Commonn nThe number of carbons in the alkane determines th
10、e namen nall alkanes with four carbons are butanes,those with five carbons are pentanes,etc.n niso-indicates the chain terminates in-CH(CH3)2;neo-that it terminates in-C(CH3)3第16页/共70页第十七页，共70页。Classification of C&Hn nPrimary(1)C:a carbon bonded to one other carbonn n1 H:a hydrogen bonded to a 1 car
11、bonn nSecondary(2)C:a carbon bonded to two other carbonsn n2 H:a hydrogen bonded to a 2 carbonn nTertiary(3)C:a carbon bonded to three other carbonsn n3 H:a hydrogen bonded to a 3carbonn nQuaternary(4)C:a carbon bonded to four other carbons第17页/共70页第十八页，共70页。Cycloalkanesn nGeneral formula CnH2nn nfi
12、ve-and six-membered rings are the most commonn nStructure and nomenclaturen nto name,prefix the name of the corresponding open-chain alkane with cyclo-,and name each substituent on the ringn nif only one substituent,no need to give it a numbern nif two substituents,number from the substituent of low
13、er alphabetical ordern nif three or more substituents,number to give them the lowest set of numbers and then list substituents in alphabetical order第18页/共70页第十九页，共70页。Cycloalkanesn nLine-angle drawingsn neach line represents a C-C bondn neach vertex and line ending represents a C第19页/共70页第二十页，共70页。C
14、ycloalkanesn nExample:Example:name these cycloalkanes name these cycloalkanes第20页/共70页第二十一页，共70页。Bicycloalkanesn nBicycloalkane:an alkane that contains two rings that share two carbonsBicyclo4.4.0decane(Decalin)Bicyclo4.3.0nonane(Hydrindane)Bicyclo2.2.1heptane(Norbornane)第21页/共70页第二十二页，共70页。Bicycloa
15、lkanesn nNomenclaturen nparent is the alkane of the same number of carbons as are in the ringsn nnumber from a bridgehead,along longest bridge back to the bridgehead,then along the next longest bridge,etc.n nshow the lengths of bridges in brackets,from longest to shortest第22页/共70页第二十三页，共70页。IUPAC-Ge
16、neraln nprefix-infix-suffixn nprefix tells the number of carbon atoms in the parent n ninfix tells the nature of the carbon-carbon bondsn nsuffix tells the class of compoundone or more triple bondsone or more double bonds all single bonds-yn-en-an-Nature of Carbon-Carbon Bonds in the Parent ChainInf
17、ixSuffix Class-e-ol-al-one-oic acidhydrocarbonalcoholaldehydeketonecarboxylic acid-amineamine第23页/共70页第二十四页，共70页。IUPAC-Generalprop-en-e=propeneeth-an-ol=ethanolbut-an-one=butanonebut-an-al=butanalpent-an-oic acid=pentanoic acidcyclohex-an-ol=cyclohexanoleth-yn-e=ethyneeth-an-amine=ethanamine第24页/共70
18、页第二十五页，共70页。Conformationsn nConformation:any three-dimensional arrangement of atoms in a molecule that results from rotation about a single bondn nNewman projection:a way to view a molecule by looking along a carbon-carbon single bond第25页/共70页第二十六页，共70页。Conformationsn nStaggered conformation:a confo
19、rmation about a carbon-carbon single bond in which the atoms or groups on one carbon are as far apart as possible from the atoms or groups on an adjacent carbon第26页/共70页第二十七页，共70页。Conformationsn nEclipsed conformation:a conformation about a carbon-carbon single bond in which the atoms or groups of a
20、toms on one carbon are as close as possible to the atoms or groups of atoms on an adjacent carbon第27页/共70页第二十八页，共70页。Conformationsn nTorsional strain n nalso called eclipsed interaction strainn nstrain that arises when nonbonded atoms separated by three bonds are forced from a staggered conformation
21、 to an eclipsed conformationn nthe torsional strain between eclipsed and staggered ethane is approximately 12.6 kJ(3.0 kcal)/mol第28页/共70页第二十九页，共70页。Conformationsn nDihedral angle(Q):the angle created by two intersecting planes第29页/共70页第三十页，共70页。Conformationsn nEthane as a function of dihedral angle第
22、30页/共70页第三十一页，共70页。Conformationsn nThe origin of torsional strain in ethanen noriginally thought to be caused by repulsion between eclipsed hydrogen nuclein nalternatively,caused by repulsion between electron clouds of eclipsed C-H bondsn ntheoretical molecular orbital calculations suggest that the
23、energy difference is not caused by destabilization of the eclipsed conformation but rather by stabilization of the staggered conformationn nthis stabilization arises from the small donor-acceptor interaction between a C-H bonding MO of one carbon and the C-H antibonding MO on an adjacent carbon;this
24、 stabilization is lost when a staggered conformation is converted to an eclipsed conformation第31页/共70页第三十二页，共70页。Conformationsn nanti conformationn na conformation about a single bond in which the groups lie at a dihedral angle of 180第32页/共70页第三十三页，共70页。Conformationsn nSteric strain(nonbonded intera
25、ction strain):n nthe strain that arises when atoms separated by four or more bonds are forced closer to each other than their atomic(contact)radii will allown nAngle strain:n nstrain that arises when a bond angle is either compressed or expanded compared to its optimal valuen nThe total of all types
26、 of strain can be calculated by molecular mechanics programsn nsuch calculations can determine the lowest energy arrangement of atoms in a given conformation,a process called energy minimization第33页/共70页第三十四页，共70页。Conformationsn nconformations of butane as a function of dihedral angle第34页/共70页第三十五页，
27、共70页。Anti Butanen nEnergy-minimized anti conformationn nthe C-C-C bond angle is 111.9 and all H-C-H bond angles are between 107.4 and 107.9n nthe calculated strain is 9.2 kJ(2.2 kcal)/mol第35页/共70页第三十六页，共70页。Eclipsed Butanen ncalculated energy difference between(a)the non-energy-minimized and(b)the e
28、nergy-minimized eclipsed conformations is 5.6 kJ(0.86 kcal)/mol第36页/共70页第三十七页，共70页。Cyclopropanen nangle strain:the C-C-C bond angles are compressed from 109.5 to 60n ntorsional strain:there are 6 sets of eclipsed hydrogen interactionsn nstrain energy is about 116 kJ(27.7 kcal)/mol第37页/共70页第三十八页，共70页
29、。Cyclobutanen npuckering from planar cyclobutane reduces torsional strain but increases angle strainn nthe conformation of minimum energy is a puckered“butterfly”conformationn nstrain energy is about 110 kJ(26.3 kcal)/mol第38页/共70页第三十九页，共70页。Cyclopentanen npuckering from planar cyclopentane reduces t
30、orsional strain,but increases angle stainn nthe conformation of minimum energy is a puckered“envelope”conformationn nstrain energy is about 42 kJ(6.5 kcal)/mol第39页/共70页第四十页，共70页。Cyclohexanen nChair conformation:the most stable puckered conformation of a cyclohexane ringn n all bond C-C-C bond angles
31、 are 110.9 n nall bonds on adjacent carbons are staggered第40页/共70页第四十一页，共70页。Cyclohexanen nIn a chair conformation,six H are equatorial and six are axial第41页/共70页第四十二页，共70页。Cyclohexanen nFor cyclohexane,there are two equivalent chair conformationsn nall C-H bonds equatorial in one chair are axial in
32、 the alternative chair,and vice versa第42页/共70页第四十三页，共70页。Cyclohexanen nBoat conformation:a puckered conformation of a cyclohexane ring in which carbons 1 and 4 are bent toward each othern nthere are four sets of eclipsed C-H interactions and one flagpole interaction n na boat conformation is less st
33、able than a chair conformation by 27 kJ(6.5 kcal)/mol第43页/共70页第四十四页，共70页。Cyclohexanen nTwist-boat conformationn napproximately 41.8 kJ(5.5 kcal)/mol less stable than a chair conformation n napproximately 6.3 kJ(1.5 kcal)/mol more stable than a boat conformation第44页/共70页第四十五页，共70页。Cyclohexane第45页/共70
34、页第四十六页，共70页。n nEquatorial and axial methyl conformationsMethylcyclohexane第46页/共70页第四十七页，共70页。G G0 0 axial-equatorial axial-equatorialn ngiven the difference in strain energy between axial and equatorial conformations,it is possible to calculate the ratio of conformations using the following relation
35、ship第47页/共70页第四十八页，共70页。Cis,Trans Isomerismn nStereoisomers:compounds that have n nthe same molecular formula n nthe same connectivity n na different orientation of their atoms in spacen nCis,trans isomers n nstereoisomers that are the result of the presence of either a ring(this chapter)or a carbon
36、-carbon double bond(Chapter 5)第48页/共70页第四十九页，共70页。Isomersn nrelationships among isomers第49页/共70页第五十页，共70页。Cis,Trans Isomersn n1,2-Dimethylcyclopentane第50页/共70页第五十一页，共70页。Cis,Trans Isomerismn n1,4-Dimethylcyclohexane第51页/共70页第五十二页，共70页。Cis,Trans Isomerismn ntrans-1,4-Dimethylcyclohexanen nthe diequat
37、orial-methyl chair conformation is more stable by approximately 2 x(7.28)=14.56 kJ/mol第52页/共70页第五十三页，共70页。Cis,Trans Isomerismn ncis-1,4-Dimethylcyclohexane第53页/共70页第五十四页，共70页。Cis,Trans Isomerismn nThe decalins第54页/共70页第五十五页，共70页。Steroidsn nThe steroid nucleusn nCholestanol第55页/共70页第五十六页，共70页。Bicyclo
38、alkanesn nNorbornane drawn from three different perspectives第56页/共70页第五十七页，共70页。Bicycloalkanesn nAdamantane第57页/共70页第五十八页，共70页。Physical Propertiesn nIntermolecular forces of attraction(example)n nion-ion(Na+and Cl-in NaCl)n nion-dipole (Na+and Cl-solvated in aqueous solution)n ndipole-dipole and hyd
39、rogen bondingn ndispersion forces(very weak electrostatic attraction between temporary dipoles)第58页/共70页第五十九页，共70页。Physical Propertiesn nLow-molecular-weight alkanes(methane.butane)are gases at room temperaturen nHigher molecular-weight alkanes(pentane,decane,gasoline,kerosene)are liquids at room te
40、mperaturen nHigh-molecular-weight alkanes(paraffin wax)are semisolids or solids at room temperature第59页/共70页第六十页，共70页。Physical Propertiesn nConstitutional isomers have different physical properties第60页/共70页第六十一页，共70页。Oxidation of Alkanesn nOxidation is the basis for their use as energy sources for h
41、eat and powern nheat of combustion:heat released when one mole of a substance in its standard state is oxidized to carbon dioxide and water第61页/共70页第六十二页，共70页。Heat of Combustionn nHeat of combustion for constitutional isomers第62页/共70页第六十三页，共70页。Heats of Combustionn nFor constitutional isomers kJ(kca
42、l)/mol-5470.6(-1307.5)-5465.6(-1306.3)-5458.4(1304.6)-5451.8(1303.0)8CO2+9H2O第63页/共70页第六十四页，共70页。Heat of Combustionn nstrain in cycloalkane rings as determined by heats of combustion第64页/共70页第六十五页，共70页。Sources of Alkanesn nNatural gas n n90-95%methanen nPetroleumn ngases(bp below 20C)n nnaphthas,inc
43、luding gasoline(bp 20-200C)n nkerosene(bp 175-275C)n nfuel oil(bp 250-400C)n nlubricating oils(bp above 350C)n nasphalt(residue after distillation)n nCoal第65页/共70页第六十六页，共70页。Gasolinen nOctane rating:the percent 2,2,4-trimethylpentane(isooctane)in a mixture the percent 2,2,4-trimethylpentane(isooctan
44、e)in a mixture of isooctane and heptane that has equivalent antiknock propertiesof isooctane and heptane that has equivalent antiknock properties第66页/共70页第六十七页，共70页。Synthesis Gasn nA mixture of carbon monoxide and hydrogen in varying proportions which depend on the means by which it is produced第67页/
45、共70页第六十八页，共70页。Synthesis Gasn nSynthesis gas is a feedstock for the industrial production of methanol and acetic acidn nit is likely that industrial routes to other organic chemicals from coal via methanol will also be developed第68页/共70页第六十九页，共70页。Alkanes andCycloalkanesEnd Chapter 2End Chapter 2第69页/共70页第七十页，共70页。