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Introduction to Organic Chemistry (Carbon Chemistry)!! Carbon has the ability to form long chains of atoms held together by strong covalent bonds. Molecules with over 700 carbon atoms bonded together are not uncommon! The carbon-carbon single bond is very strong and very stable – it takes strong UV light or lots of heat to crack it. The PROPERTIES OF ORGANIC COMPOUNDS are generally determined by three factors: a) The carbon skeleton is a very stable, chemically unreactive structure. b) The presence of double or triple bonds increases the reactivity of carbon skeletons. c) “Functional groups" which are other atoms or groups of atoms attached to the carbon skeleton give organic compounds their special chemical properties. For example alcohols derive their special properties from the presence of the -OH group, carboxylic acids possess the -COOH group, etc. Table 1: The Alkanes: compounds of only carbon and hydrogen with only single bonds Molecular Formula Structural Formula Name expanded condensed H CH4 CH4 Methane H C Boiling Point C -162 H H C2H6 H H H C C H H CH3-CH3 ethane CH3-CH2-CH3 Propane H Butane Pentane Hexane Heptane Octane Nonane Decane “Monkeys Eat Purple Bananas” or whatever…. -89 ALKYL GROUPS Carbon chains that ‘branch’ off a longer chain are named abit differently, they are called "alkyl" groups. Complete the following chart. Parent Alkane Alkyl Group Name H H CH4 methane -CH3 Methyl H C H H C2H6 ethane H H H C C H H C H H H H H C C H H -CH2CH3 Ethyl H C3H8 propane STRUCTURAL ISOMERS - compounds that have the same molecular formulae but different structural formulae are called structural isomers. One check on drawing isomers, is that they must have different names Example 1: C4H10 has two (2) structural isomers: 1) butane as CH3-CH2-CH2-CH3 i.e. H OR 2) 2-methyl propane H H H C C C C H H H H H or CH3 CH3 CH H CH3 Types of drawings: structural formula: shows all atoms and all bonds condensed structural formula: shows all atoms and only the bonds that are important to help distinguish compounds. CH2 =O. simplified structural formulae: the atoms C and H are not written. Naming Alkanes (hydrocarbons with only C-C single bonds): 1. Identify the longest chain – this is the base name. 2. Number the longest chain in a way to give any branches (alkyl groups) the lowest possible numbers. 3. Name the branches in alphabetical order, using a number to specifiy the position AND using prefixes (di, tri…) if there are more than one of the same type. (e.g. 2,2-dimethylpentane)