[3.3.1] Introduction to Organic Chemistry Flashcards
Nomenclature, Reaction Mechanisms & Isomerism.
What is a hydrocarbon?
A compound consisting of hydrogen and carbon only.
What does saturated mean?
Contain single carbon-carbon bonds only.
What does unsaturated mean?
Contains a C=C double bond.
What is the molecular formula?
Shows the actual number of each type of atom.
What is the empirical formula?
Shows the simplest whole number ratio of atoms of each element in a compound.
What is the general formula?
Algebraic formula for a homologous series e.g. for alkenes CnH2n.
What is the structural formula?
Shows the minimal detail that shows the arrangement of atoms in a molecule e.g. for butane = CH₃CH₂CH₂CH₃.
What is the displayed formula?
Shows all the covalent bonds and atoms present in a molecule.
What is the skeletal formula?
Shows the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups.
Draw the skeletal formula for butan-1-ol.
What is a functional group?
An atom or group of atoms which when present in different molecules causes them to have similar chemical properties.
What is a homologous series? What are the characteristics of one?
- Homologous series are families of organic compounds with the same functional group and same general formula.
CHARACTERISTICS
- They show a gradual change in physical properties.
- e.g. boiling point.
- Each member differs by CH₂ from the last.
- Same chemical properties.
Give some examples of homologous series.
- Alkane.
- Alkenes.
- Alcohols.
- Halogenoalkanes.
- Aldehydes.
- Ketones.
- Carboxylic acids.
- Esters.
What are the general rules for naming carbon chains?
- Count the longest chain and name appropriately.
- Meth = 1 carbon atom.
- Eth = 2 carbon atoms.
- Prop = 3 carbon atoms.
- But = 4 carbon atoms.
- Pent = 5 carbon atoms.
- Hex = 6 carbon atoms.
- Hept = 7 carbon atoms.
- Oct = 8 carbon atoms.
- Non = 9 carbon atoms.
- Dec = 10 carbon atoms
- Find any branched chains and count how many carbons they contain.
- Add the appropriate prefix for each branched chain.
- e.g. CH₃ = methyl, C₂H₅ = ethyl, C₃H₇ = propyl…
What are the general rules for naming functional groups?
- Functional group is named by a prefix or suffix.
- If the suffix starts with a vowel, remove the -e from the stem alkane name.
- e.g. Propan-1-ol, butan-1-amine, ethanoic acid, ethanoylchloride, butanamide.
- 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 -e from the stem alkane name.
- e.g. Propanenitrile, ethane-1,2-diol, proanedioic acid, propane1,2,3-triol, pentane-2,4-dione.
- If the suffix starts with a vowel, remove the -e from the stem alkane name.
- 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 if they are needed to avoid ambiguity.
- The functional groups take precedence over branched chains in giving the lowest number.
- Where there are two or more of the same groups, di-, tri-, tetra-, penta- and hexa- are used.
- Words are separated by numbers with dashes, numbers are separated by commas and if there is more than one functional group or side chain, the groups are listed in alphabetical order (ignoring any di, tri etc.).
- 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 takes the suffix (and the lowest number on the carbon chain), with all others taking the prefix form.
- Order of priority highest first: carboxylic acids > aldehydes > ketones > alcohols > alkenes > halogenoalkanes.
How do you name alkanes?
- Using the suffix -ane.
Write the structural formula and draw the skeletal formula of butane.
Draw the skeletal formula for 2-methylbutane.
Draw the skeletal formula for cyclohexane.
Name this molecule.
Methylpropane.
How do you name alkenes?
- A double bond will be between two carbon atoms. Use the lower number of the two to show the position of the double bond.
- e.g. But-2-ene.
- The name for alkenes may include E or Z at the start to show the type of stereoisomer.
- e.g. Z-but-2-ene.
- If more than one double bond is present, then suffix ends in diene or triene.
- The stem ends in a.
e.g. penta-1,3-diene.
- The stem ends in a.
- The suffix -en for alkenes can go in front of other suffixes.
- e.g. 2-bromobut-3-en-1-ol and E-but-2-enoic acid.
- The alcohol and carboxylic acid groups have higher priority than the alkene group so take precedence with numbering.
- e.g. 2-bromobut-3-en-1-ol and E-but-2-enoic acid.
Draw the skeletal formula for but-2-ene.
Draw the skeletal formula for cyclohexene.
Draw the skeletal formulae of Z-but-2-ene, penta-1,3-diene and E-but-2-enoic acid.
Write the structural formula of 2-bromobut-3-en-1ol
Write the structural formula and draw the skeletal formula of propene.
How do you name halogenoalkanes?
- Class the halogen as a substituent on the carbon chain and use the prefixes -fluoro, -chloro, -bromo or -iodo.
- Give the position number if necessary.
- Multiple functional groups and side chains are listed in alphabetical order ignoring any di, tri etc.)
- e.g. 2,3-dicholoro-1-fluoro-3-methylpentane.
Draw the displayed formula of 2-bromobutane.