Chapter 1 - Nomenclature Flashcards
What is the general formula for alkanes?
The general formula for alkanes is
CnH2n+2
where n is an integer
Name the first ten straight chain alkanes
- Methane: CH4
- Ethane: CH3CH3
- Propane: CH3CH2CH3
- Butane: CH3CH2CH2CH3
- Pentane: CH3CH2CH2CH2CH3
- Hexane: CH3(CH2)4CH3
- Heptane: CH3(CH2)5CH3
- Octane: CH3(CH2)6CH3
- Nonane: CH3(CH2)7CH3
- Decane: CH3(CH2)8CH3
What are the six steps to naming a compound?
- Find the highest priority functional group (most oxidized carbon) in the compound. This carbon receives the number 1, and the compund will end with the IUPAC suffix for this group, e.g. -oate for an ester or -al for an aldehyde.
- Find the longest continuous carbon chain attached to the highest priority functional group in the compound; numbering begins here, with the functional carbon receiving the number 1. If there are two or more chains of equal length, the most substituted chain gets priority.
- Number the chain so that the most substituents get the lowest number.
- Name the substituents. Carbon chain substituents are named according to their number root followed by -yl. These terms are places at the beginning of the compound, as prefix, followed by the name of the longest chain.
- Assign a number to each substituent. This applies even if the prefixes di-, tri- or tetra- are used.
- Complete the name. Begin with the substituents, listed in alphabetical order; with each substituent name preceeded by its assigned number.
Name the substituent:
t-butyl
Name the substituent:
neopentyl
Name the substituent:
isopropyl
Name the substituent:
sec-butyl
Name the substituent:
isobutyl
General formula for cycloalkanes:
The general formula for cycloalkanes is
CnH2n
where n is an integer. For every ring in the structure there will be two fewer hydrogens than in the straight-chain counterpart. Cycloalkanes have one degree of unsaturation (two fewer H than straight chain) for each ring.
How are ring structures named?
Cycloalkanes are named by the number of carbon atoms in the cyclo-. The ring is numbered starting at the point of greatest substitution, with substituents receiving the lowest possible numbers.
How is functional group priority determined?
Priority is based on the oxidation state of the functional group’s carbon. Oxidation is the loss of electrons (LEO), and so the most electropositive carbon will be the highest priority. Generally, however, the carbon with the most bonds to oxygen tends to be the most oxidized.
Ethylene: formula and structure
The smallest alkene: CH2CH2
Propylene: Formula and structure
CH2CHCH3
General formula for an alkene
The general formula for alkenes is
CnH2n
where n is an integer. For every double bond in the structure there will be two fewer hydrogens than in the straight-chain counterpart. Alkenes have one degree of unsaturation (two fewer H than straight chain) for each double bond.
Name the following alkanes:
- n-hexane
- 3-methylpentane
- 2-methylpentane
- 2,2-dimethylbutane
- 2,3-dimethylbutane
Vynil derivatives
Monosubstituted ethylenes (ethenyl-), such as chloroethene (vynil chloride) below. Vynil derivatives have a substituent group attached to the double-bonded carbon.
Allyl derivatives
A substituent with the structural formula H2C=CH-CH2-R, where R is the rest of the molecule. It consists of a methylene bridge (-CH2-) attached to a vinyl group (-CH=CH2). 3-bromo-1-propene (allyl bromide) is an example.
Name the following compound
2-propen-1-ol (allyl-alcohol)
Name the following compound. What is interesting about this molecule?
Ethenol (vynil alcohol). Vynil alcohols are unstabel and exist in equilibrium with their aldehyde counterparts: under normal conditions, ethenol converts (tautomerizes) to acetaldehyde.
Methylene
A methylene group is any part of a molecule that consists of two hydrogenatoms bound to a carbon atom, which is connected to the remainder of the molecule by a double bond. Methylene cyclohexanse, below, is an example.
If there is a tie when assigning priority in a molecule with double and triple bonds, which takes precedence?
The double bond
Cycloalkenes
Rings containing one or more double bonds. These are named like cycloalkanes, but with the suffix –cyclo(x)ene rather than –cyclo(x)ane. If there is only one double bond and no other substituents the ring does not have to be numbered, e.g. cyclohexene:
Name the following compound.
trans-4-methylcyclooctene
cis and trans configurations of alkenes
Alkynes
Compounds with at least one carbon-carbon triple bond. Alkynes have the suffix **-yne **and adhere to the general formula CnH2n-2. An alkyne has two degrees of unsaturation because it has two pi bonds. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2(IUPAC, ethyne)
Name the following compound
Acetylene (IUPAC, ethyne)
Name the following compound
4-methylhex-2-yne