introduction to organic

• Hydrocarbon


  Compound consisting of hydrogen and carbon only
• Molecular formula


  Formula which shows the actual number of each type of atom
• Unsaturated


  Contains a C=C double bond
• Saturated


  Contain single carbon-carbon bonds only
• General formula


  Algebraic formula for a homologous series e.g. CnH2n
• Empirical formula


  Shows the simplest whole number ratio of atoms of each element in the compound
• 3.1 Organic: Basic Concepts
• Displayed formula


  Show all the covalent bonds and atoms present in a molecule
• When drawing organic compounds add the hydrogen atoms so that each carbon has 4 bonds
• The shape around the carbon atom in saturated hydrocarbons is tetrahedral and the bond angle is 109.5o
• Skeletal formula


  Shows the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups
• Structural formula


  Shows the minimal detail that shows the arrangement of atoms in a molecule
• Structural formula examples


  • CH3CH2CH2CH3 or CH3(CH2)2CH3, 2-methylbutane, But-2-ene, Butan-1-ol, cyclohexane, cyclohexene
• Functional group


  An atom or group of atoms which when present in different molecules causes them to have similar chemical properties
• Homologous series


  Families of organic compounds with the same functional group and same general formula. They show a gradual change in physical properties (e.g. boiling point), each member differs by CH2 from the last, and have same chemical properties.
• Homologous series examples


  • Alkane, Alkenes, Alcohols, Halogenoalkanes, Aldehydes, Ketones, Carboxylic acids, Esters
• When compounds contain more than one functional group, the order of precedence determines which groups are named with prefix or suffix forms. The highest precedence group takes the suffix (and the lowest number on the carbon chain), with all others taking the prefix form. However, double and triple C-C bonds only take suffix form.
• Order of priority highest first

  • Carboxylic acids>aldehydes>ketones>alcohols>alkenes>halogenoalkanes
• Count the longest carbon chain and name appropriately. Find any branched chains and count how many carbons they contain. Add the appropriate prefix for each branch chain.
• Branched chain prefixes


  • -CH3 methyl or -C2H5 ethyl –C3H7 propyl
• The position of the functional group on the carbon chain is given by a number – counting from the end of the molecule that gives the functional group the lowest number.
• For aldehydes, carboxylic acids & nitriles, the functional group is always on carbon 1.
• We only include numbers, however, if they are needed to avoid ambiguity.
• Words are separated by numbers with dashes, numbers are separated by commas.
• If there is more than one functional group or side chain, the groups are listed in alphabetical order (ignoring any di, tri).
• When using a suffix, add in the following way: If the suffix starts with a vowel- remove the –e from the stem alkane name. If the suffix starts with a consonant or there are two or more of a functional group meaning di, or tri needs to be used then do not remove the the –e from the stem alkane name.
• The functional groups take precedence over branched chains in giving the lowest number.
• Examples of naming with multiple functional groups and side chains

  • CH2FCH2CHBrCH2CH3 - 3-bromo-1-fluoropentane, CH2FCCl2CH2CH3 - 2,2-dichloro-1-fluorobutane, 2,3-dibromopentane, CHCl3 - trichloromethane
• Where there are two or more of the same groups, di-, tri- ,tetra-, penta- or hexa- are used.
• Examples of naming with multiple functional groups

  • Ethane-1,2-diol, propane-1,2,3-triol
• Halogenoalkanes


  Class the halogen as a substituent on the C chain and use the prefixes -fluoro, -chloro, -bromo, or –iodo. (Give the position number if necessary)
• Alcohols


  These have the ending -ol and if necessary the position number for the OH group is added between the name stem and the –ol. If the compound has an –OH group in addition to another functional group with a higher priority, the priority group gets the suffix ending and the OH can be named with the prefix hydroxy-.
• Alkenes


  The double bond will be between two carbons. Use the lower number of the two to show the position of the double bond. The name for alkenes may include E or Z at start to show the type of stereoisomer.
• Examples of naming with multiple functional groups and side chains

  • 2-bromobut-3-en-1-ol, 2,3-dichloro-1-fluoro-3-methylpentane, 5,5-dibromo-4-iodo-3-methylpent-1-ene, E-3,6-dichlorohex-4-en-1-ol
• Aldehydes


  An aldehyde's name ends in –al. It always has the C=O bond on the first carbon of the chain so it does not need an extra number.
• Ketones


  Ketones end in -one. When ketones have 5C's or more in a chain then it needs a number to show the position of the double bond.
• Carboxylic acids


  These have the ending -oic acid but no number is necessary for the acid group as it must always be at the end of the chain. The numbering always starts from the carboxylic acid end.
• Ketones with multiple groups

  If there are two ketone groups then di is put before –one and an e is added to the stem.
• Aldehydes with multiple groups


  If two aldehyde groups then di is put before –al and an e is added to the stem.
• Aldehydes


  • An aldehyde's name ends in –al
  • It always has the C=O bond on the first carbon of the chain so it does not need an extra number. It is by default number one carbon on the chain