清华大学有机化学李艳梅老师课件第四章教案资料.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Chapter 4,Cycloalkanes,第四章 环烷烃,Organic Chemistry A(1),By Prof.Li Yan-Mei,Tsinghua University,Content,4.1 Classification,Isomerization and nomenclature,4.2 Structure of cycloalkanes,4.3 Physical properties&spectrum data,4.4 Chemical properties,4.5 Preparation(learn on your own),4.1 Classification,Isomerization and nomenclature,4.1.1 Classification,4.1.2 Isomerism,4.1.3 Nomenclature,4.1.1 Classification,By the size of the ring,按环的大小,Small rings,Medium rings,Common rings,Large rings,C,3,C,4,C,8,C,12,C,5,C,7,C,13,By the saturation,按不饱和度,C,n,H,2n,C,n,H,2n-2,C,n,H,2n-4,Cycloalkanes,环烷,Cyclo olefines,环烯,Cyclo alkynes,环炔,Monocyclic compounds,单环,By the number of the rings,按环的数目,Polyring compounds,多环,Fused ring,稠环,Bridged ring,桥环,Spiro rings,螺环,两环之间共用一个碳原子,两环之间共用一根共价键（共用两个直接相连的碳原子）,两环之间共用两个不直接相连的碳原子,螺原子,桥头碳,To define the number of the rings:,The number of cutting you need to get a chain molecule out of a poly ring compound,几环？,将桥（稠）环烃变为链状化合物时需要断裂的碳链数。如需断裂两次，则为二环化合物，断裂三次则为三环化合物。,Some interesting bridging compounds,Cubane,立方烷,Primane,棱 烷,Diamentane,金刚烷,篮 烷,4.1.2 Isomerism,Constitutional isomers are derivated from the change of size of rings and length of side chains,C,5,H,10,环的大小及侧链长短与位置变化,4.1.3 Nomenclature,命名,4.1.3.1 Monocyclic alkane,单环烷烃,1,When the side chain is not very complicate:,当支链不复杂时，以环烷烃为母体,1,2-,二甲基环戊烷,甲基环戊烷,1-,甲基,-,3-,乙基,环戊烷,4-,甲基,-3-,乙基,-1-,丙基环己烷,2,When the side chain is complicate or difficult to name:,当支链较复杂或不易命名时，以环烷基为取代基,3-cyclohexylhexane,3-,环己基己烷,3,When two rings are connected,两环相连时,Cyclopropylcyclohexane,环丙基环己烷,Cyclopropylcyclopropane,环丙基环丙烷,4,Cis and trans isomerism:,Cis-1,4-dimethylcyclohexane,Trans-1,4-dimethylcyclohexane,How to name this compound?,4.1.3.2 Polyring alkane,多环烷烃,1,Spiro cycloalkanes,螺环烃,1,）选母体：根据成环的总碳原子数，称为“螺某烷”。,2,）编号：从小环开始；从第一个非螺原子开始。,3,）书写：先写词头“螺”,方括号内沿着编号方向写出每个环中除螺原子,外的每个环的碳原子数,数字之间用圆点隔开,最后写出包括螺原子在内碳原子数的烷烃名称,1,2,3,4,5,6,7,8,9,10,螺,4.5,癸烷,1,“小原则”：在不违背螺环烃命名的“大”原则基础上，在编号时应尽可能令取代基的位号最小。,1,2,3,4,5,6,7,8,9,10,1-,甲基螺,4.5,癸烷,思考！,spiro4.5decane,螺,4.5,癸烷,spiro5.5undecane,螺,5.5,十一烷,6-methylspiro4.5decane,6-,甲基,4.5,癸烷,4-methylspiro2.4heptane,4-,甲基,2.4,庚烷,1,）选母体：根据成环的总碳原子数及环数，称为“,n,环某烷”。,2,）编号：从桥头碳开始；从最长桥开始。,3,）书写：先写环数,方括号内沿着编号方向写出每个环中除桥头碳原子,外的每个环的碳原子数,数字之间用圆点隔开,最后写出包括桥头碳原子在内碳原子数的烷烃名称,2,Bridged-ring alkane and fused-ring alkane,桥环烃和稠环烃,二环,3.2.1,辛烷,2,7,7-,三甲基二环,2.2.1,庚烷,注意：有两个桥头碳可供选择,二环,1.2.0,丁烷,For polycyclic compound as following,多元环,Deciding the main ring,选“主环”：最大的环,Choosing the main bridged carbon,选“主桥头碳”：主环与非主环的最长桥共用的桥头碳,Decide the serial number,编号：从主桥头碳开始；从最长桥开始,Naming the compound,书写（注意与非主桥相连的桥需注明所连桥的编号）,1,2,3,4,5,6,7,Tricyclic2.2.1.0,2.6,heptane,思考：,1,2,3,4,5,6,7,8,9,10,Tricyclic3.2.2.1,2.7,decane,tricyclic3.2.2.1,2.7,dacane,Fused ring,naphthalene,Hydrogenated naphthalene,Endo/exa,区别：母体！,4.2.1 Baeyers strain theory,4.2.2 Heat of combustion for cycloalkane,4.2.3 Current opinions,4.2.4 Conformations of cyclohexane,4.2.5 Configuration of decalin,4.2 Structure of cycloalkanes,Before 1880,1883,Only penta rings and hexa rings were found.It was regarded that rings smaller than penta rings and bigger than hexa rings do not exist,or are not stable.,W.H.Perkin synthesized C,3,C,4,and identified the relative reactivity:double bond C,3,C,4,while C,5,and C,6,rings are relatively more stable.,1885,A.von.Baeyer put forward the strain theory,4.2.1 Baeyers strain theory Bayers,张力学说,Assumption:,1,carbon atoms in the ring are on the same plane;,成环的碳原子均在同一同面上，且呈正多边形,2,carbon atoms are,sp,3,carbon atoms;,碳原子采取,sp,3,杂化形式，正常键角应为约,109.5,度,3,to meet some special angles in the ring,the bonds have to be bending;,为了满足平面正多边形的内角要求，成环的键必须向内或向外“屈挠”，“屈挠”的程度越大，体系越不稳定。,More bending,More angle strain,Higher energy,Less stability,60,o,90,o,108,o,120,o,129,o,Most stable?,可解释一些体系的稳定性特点，但还有一些体系无法解释。,4.2.2 Heat of combustion for cycloalkane,Heat of combustion per CH,2,kJ/mol,697,686,664,659,662,658,Do not fit the strain theory!,角张力（,Baeyer,张力）,扭转张力,范氏力,影响环体系稳定性的主要因素：,4.2.3 Current opinions,C,C,C,105.5,o,C,C,C,Bent Bond,（弯曲键、香蕉键）,角张力：,109.5,0,-105.5,0,=4,0,1,2,3,扭转张力：,三组,H,C,C,均处于全重叠式,蝴蝶状,蝴蝶式,1,2,3,4,A nonplanar conformation,非平面构象,也存在弯曲键,111.5,0,角张力：,111.5,0,109.5,0,=2,0,部分交叉式,扭转张力较小,6.3kJ/mol higher,全重叠式,信封式 半椅式,如果：,具有多组全重叠式,Large ring,多于,13,个碳原子的环体系中，分子链一般呈皱折形,Strain energy in cycloalkanes,Name,Angle strain,Twist strain,Van de waals,C,3,Great,Medium,No,C,4,Great,Medium,No,C,5,Slight,Medium,No,C,6,No,No,No,C,7,C,12,Medium,Medium,Great,C,12,No,No,No,4.2.4 Conformations of cyclohexane,Year,Name of scientist,Point of view,1883,Baeyer,Assumes that six carbon atoms are on the same plane,1890,H.Sachse,Two conformations may exist,1915-1918,W.M.Mohr,Chair model and boat model,1920,Cyclohexane was proved to be nonplanar experimentally,1943,O.Hassel,Chair model is most stable,(electron diffraction method),1950,D.Barton,Conformation analysis of cyclohexane,A history,4.2.4.1 Conformation of cyclohexane,250pm,C,3,50pm,Chair Structure,椅式,1,2,3,4,5,6,部分交叉式，扭转张力较小,Axial bond,Equatorial bond,Two types of C-H bonds in chair structure,a,键,e,键,Boat structure,船式结构,183pm,Van de waal radius of H atom is 120pm,so the two adjacent hydrogen atoms causes serious excluding.,存在范氏力,1,2,3,4,5,6,全重叠式，存在扭转张力,2,、,3,、,5,、,6,碳处于同一平面,Flagpole interaction,Twist boat structure,扭船式,H,H,H,H,H,H,H,H,H,H,H,H,1,2,3,4,5,6,1,2,3,4,5,6,1,2,3,4,5,6,Half chair structure,半椅式,Potential energy of the conformations,各种构象势能关系图,46kJ/mol,Potential energy,process,椅式构象之间的转变：,46kJ/mol,Potential energy,Reaction process,4.2.4.2 mono substituted cyclohexane,250pm,r.t.,5,95,Reason 1:Van de waals forces,Atom,H,CH,2,CH,3,N,P,O,R/pm,120,200,200,150,190,140,Atom,S,F,Cl,Br,I,R/pm,185,135,180,195,215,250pm,r.t.,1,3,二直立键相互作用,6,1,1,6,Reason 2:Torsional strain,a,键,e,键,6,1,6,1,结论与推论：,1,、一取代时，取代基趋向于处于,e,键,2,、若有多个取代基，在满足顺反构型关系的前提下，则越多取代基处于,e,键时越稳定。,3,、若环上有不同取代基，在满足顺反构型关系的前提下，则大基团处于,e,键时较稳定。,4.2.4.3,double substituted cyclohexane(same groups),a,键,e,键,a,键、,e,键的顺反关系,Cis-1,2,trans-1,2,trans-1,3,1,1,cis-1,3,cis-1,4,trans-1,4,4.2.4.4 double substituted cyclohexane(different groups),Conformation with all groups on e bond is most preferred;,在满足空间构型的前提下，令尽可能多的取代基处于,e,键。,If the above condition can not be met,the group with a bigger size is on the e bond.,优先满足大基团处于,e,键。,-F,-CN -Cl,-Br,-I -OCH,3,-OH -COOH -NH,2,-CH,3,-CH,2,CH,3,-CH(CH,3,),2,-C,6,H,5,-C(CH,3,),3,注：,1,、,OH,，,NH,2,易受溶剂的影响，尤其是形成氢键时。,2,、此顺序应用于,1,2,取代时可能有误差。,练习：画出以下结构的最稳定构象,4.2.5 Configuration of decalin,十氢合萘的构型,8.7kJ/mol more stable,4.3 Physical properties&spectrum data,物理性质：,环烷烃分子较规则，不易自由摇动,分子排列紧密,熔点、沸点、密度等一般高于相应的直链烷烃,a,-H,e,-H,Theoretically,e-H,is 0.20.5 ppm larger than,a-H,.But due to the fast transform of cyclohexane,this difference is often invisible.,cyclopropane,0.22 ,cyclobutane,=,1.96,other,=1.5,1,H-NMR,13,C-NMR,n,3 4 5 6 7 8 9 10,(ppm),-2.8 23.1 26.3 27.6 28.2 26.6 25.8 25.0,IR,环烷烃中,CH,2,的,C,H,伸缩振动受环张力的影响，波数升高，强度下降。,五元以下小环的亚甲基伸缩振动波数均大于,3000cm,-1,，大于五元的环则与直链烷烃一样。,4.4.1 Radical substitution reactions,4.4.2 Characteristic reaction,4.4.3 Oxidation,4.4 Chemical properties,4.4.1 Radical substitution reactions,纯卤素,4.4.2 Characteristic reaction,小环的特殊反应,Halogen addition,卤素的,CCl,4,溶液,Addition of hydrogen halide,开环的规律：,在含氢最多与含氢最少的碳原子之间开环。,HX,加成的规律：,H,加在含氢较多的碳上。,催化加氢的规律与此不同！,Hydrogensis,4.4.3 Oxidation,可与不饱和烃相区别,4.5 Preparation(learn on your own),由柏拉圖五立體到合成化學,幾何學上有五座奇妙的正多面體，柏拉圖稱它們是自然界最完美的五種形體。無論由任何角度來觀察，它們都是完全對稱的。每個角、每個邊、每個面都相等，所有的角都內接於一個大圓球上；而所有的邊則外切另一個小圓球。像這般的正多面體只有五個：,正四面體（,tetrahedron,）,正方體（,cube,）,正八面體（,octahedron,）,正二十面體（,icosahedron,）,正十二面體（,dodecahedron,）,如何重现其绝伦之美？,Thank you!,