化学专业英语Dr Zhang Jian zhangjian0923vip.sina.comOffice: Room 402, Chemistry BuildingOrganic ChemistryThe name organic chemistry came from the word organism. Prior to 1828, all organic compounds had been obtained from organisms or their remains. The name organic chemistry came from the word organism. Prior to 1828, all organic compounds had been obtained from organisms or their remains. The scientific philosophy back then was that the synthesis of organic compounds could only be produced within living matter while inorganic compounds were synthesized from non-living matter. A theory known as “Vitalism“ stated that a “vital force“ from living organisms was necessary to make an organic compound. 1828, a German chemist Friedrich (1800-1882) amazed the sience community by using the inorganic compound ammonium cyanate, NH4OCN to synthesize urea, H2NCONH2, an organic substance found in the urine of many animals. This led to the disappearance of the “Vitalism“ theory Today, chemists consider organic compounds to be those containing carbon and one or more other elements, most often hydrogen, oxygen, nitrogen, sulfur, or the halogens, but sometimes others as well. Organic chemistry is defined as the chemistry of carbon and its compounds. Organic Chemistryn “Organic” until mid 1800s referred to compoundsfrom living sources (mineral sources diamond and graphite were “inorganic”)n Whler in 1828 showed that urea, an organiccompound, could be made from a mineralsn Includes biological molecules, drugs, solvents, dyesn Does not include metal salts and materials (inorganic)n Does not include materials of large repeatingmolecules without sequences (polymers）Organic ChemistrynToday, organic compounds are those based oncarbon structures and organic chemistry studiescarbon and hydrogen structures and reactions.n Includes biological molecules, drugs, solvents, dyesn Does not include metal salts and materials (inorganic)n Does not include materials of large repeatingmolecules without sequences (polymers）Goal of Organic Chemistryn Learn the crucial facts and vocabulary of Organic ChemistrynDevelop theoretical intuition about how Bonding works (Molecular structure), and changes (reactivity)nTheory 1 kcal = 4.184 kJ)Bond LengthnDistance betweennuclei that leads tomaximum stabilityn If too close, theyrepel because bothare positively chargedn If too far apart,bonding is weakHybridization: sp3 Orbitals and the Structure of MethanenCarbon has 4 valence electrons (2s2 2p2)nIn CH4, all CH bonds are identical (tetrahedral)sp3 hybrid orbitals: s orbital and three p orbitalscombine to form four equivalent, unsymmetrical,tetrahedral orbitals (sppp = sp3), Pauling (1931)Tetrahedral Structure of Methanensp3 orbitals on C overlap with 1s orbitals on 4 H atomto form four identical C-H bondsnEach CH bond has a strength of 438 kJ/mol and length of 110 pmnBond angle: each HCH is 109.5, the tetrahedral angle.Hybridization: sp3 Orbitals and theStructure of EthanenTwo Cs bond to each other by overlap of an sp3 orbital from eachnThree sp3 orbitals on each C overlap with H 1s orbitals to form six CH bondsnCH bond strength in ethane 420 kJ/molnCC bond is 154 pm long and strength is 376 kJ/molnAll bond angles of ethane are tetrahedralHybridization: sp2 Orbitals and theStructure of Ethylenensp2 hybrid orbitals: 2s orbital combines with two 2porbitals, giving 3 orbitals (spp = sp2)nsp2 orbitals are in a plane with 120 anglesRemaining p orbital is perpendicular to the plane