Chemical bond and structure of organic compounds Lecture 1

Outlook Organic and inorganic compounds Structure of organic compounds and the nature of chemical bond Nomenclature of organic compounds

Organic and inorganic compounds combustion analysis: water carbon dioxide gases and minerals Antoine Laurent Lavoisier 1743-1794 two types of matter: organic inorganic

Organic and inorganic compounds Jöns Jacob Berzelius 1779-1848 Friedrich Wöhler 1800-1882 NH4OCN → (NH2)2CO Organic chemistry (1807) – study of compounds from natural sources Vitalism – organic compounds can only be produced by the vital force ammonium cyanate INORGANIC urea (carbamide) ORGANIC CH4N2O isomers – different materials – same composition

Structure of chemical compounds Isomers – different materials – same composition – different structure August Kekulé 1829-1896 Alexander Butlerov 1828-1886 1858: Carbon atom normally forms four bonds 1858: chemical structure – the way in which atoms are connected determines the nature of compounds

The nature of chemical bond Gilbert Lewis 1875-1946 chemical bond – a shared pair of electrons

The nature of chemical bond atomic number 6 6 protons in the nucleus 6 electrons in the shell 1s22s22p2

the orbitals mix - undergo hybridization four bonds in methane are formed using different electrons, but the bonds are completely equivalent the orbitals mix - undergo hybridization

Hybridization 1954, 1962 Linus Pauling 1901-1994

sp3 hybridization

sp2 hybridization ethylene

sp hybridization acetylene

Hybridization Now let’s look at the hybridization of nitrogen and oxygen atoms…

Classes of organic compounds Functional group - a characteristic group of atoms/bonds that possess a predictable chemical behavior

Classes of organic compounds

Classes of organic compounds Determine the class of organic compounds

Nomenclature of organic compounds – trivial names “What's in a name? that which we call a rose By any other word would smell as sweet.”  William Shakespeare Acetone spirit of Saturn Formic acid Raspberry ketone Squaric acid Butyric acid cubane Olympicene

Systematic nomenclature of organic compounds Name of an organic compound: parent chain substituents – radicals and functional groups multiple bonds geometric and space configuration Names of hydrocarbons Number of Carbons Name Radical 1 methane methyl 2 ethane ethyl 3 propane propyl 4 butane butyl 5 pentane pentyl 6 hexane hexyl 7 heptane heptyl 8 octane octyl 9 nonane nonyl 10 decane decyl 11 undecane undecyl 12 dodecane dodecyl

Systematic nomenclature of organic compounds Simple steps: Identify the longest carbon chain - the parent chain Identify all of the parent functional group (highest in precedence) Identify all of the side chains and other functional groups Identify double/triple bonds Number the carbons of the parent chain from the end that gives the parent functional group/multiple bonds/side chains the lowest numbers Compose the name: functional groups and side chains (alphabetically), indicate locations and the number of substituents (di, tri, tetra, etc.) parent chain double/triple bonds with numbers primary functional group

Order of precedence of functional groups Priority Functional group Prefix Suffix 1 - -oic acid 2 cyano- -nitrile 3 formyl- -al 4 oxo- -one 5 hydroxy- -ol 6 amino- -amine 7 nitro-