nomenclature Flashcards
(17 cards)
what is IUPAC?
the normal naming rules
what is a homologous series?
● a series of chemically similar compounds which conform to a general formula
● differs from next in series by a CH2
what are the IUPAC rules for naming alkanes?
● rule 1: locate longest continuous chain of carbon atoms - name of parent compound
● rule 2: name of parent compound is modified by noting what alkyl groups are attached to chain. number longest chain so alkyl group(s) will be on the lowest numbered carbon
● rule 3: when same alkyl group occurs more than once in a molecule, numbers of carbons to which they are attached are all included in the name. number of carbon is repeated as many times as group appears. number of repeated alkyl group is indicated in name by use of greek prefixes for 2, 3, 4, 5 etc (di, tri, tetra, penta etc)
● rule 4: if there are 2 or more different kinds of alkyl groups attached to parent chain, name them in alphabetical order (don’t consider greek prefixes)
● rule 5: finishing touches:
- hyphens separate numbers from names
- numbers separated by commas
methane
● molecular formula: CH4
● alkyl name: methyl
● alkyl group: -CH3
● number of carbons: 1
ethane
● molecular formula: C2H6
● alkyl name: ethyl
● alkyl group: -C2H5
● number of carbons: 2
propane
● molecular formula: C3H8
● alkyl name: propyl
● alkyl group: C3H7
● number of carbons: 3
butane
● molecular formula: C4H10
● alkyl name: butyl
● alkyl group: C4H9
● number of carbons: 4
pentane
● molecular formula: C5H12
● alkyl name: pentyl
● alkyl group: C5H11
● number of carbons: 5
hexane
● molecular formula: C6H14
● alkyl name: hexyl
● alkyl group: C6H13
● number of carbons: 6
heptane
● molecular formula: C7H16
● alkyl name: heptyl
● alkyl group: C7H15
● number of carbons: 7
octane
● molecular formula: C8H18
● alkyl name: octyl
● alkyl group: C8H17
● number of carbons: 8
nonane
● molecular formula: C9H20
● alkyl name: nonyl
● alkyl group: C9H19
● number of carbons: 9
decane
● molecular formula: C10H22
● alkyl name: decyl
● alkyl group: C10H21
● number of carbons: 10
if in ring what prefix do you add?
● add prefix cyclo
● e.g cyclohexane
what are the IUPAC rules for naming molecules containing functional groups?
● rule 1: find longest carbon chain - parent name
● rule 2: decide which is the dominant functional group
● rule 3: number position of functional group using lowest possible number (where a number - usually 1 - is not necessary, do not write it: carboxylic acids and aldehyde)
● rule 4: if there are no suffix functional group, prefixes are prioritised:
bromo-chloro-fluoro-iodo > nitro > methyl-ethyl-propyl
● rule 5: if other functional groups are present in compounds in rule 3, they follow priority in rule 4 after giving suffix functional group 1st position
● rule 6: use greek prefixes for more than 1 functional group or alkyl group of same type
● rule 7: functional groups written alphabetically
● rule 8: where 2 names which usually suffixes are needed, ending for acid takes precedence over aldehyde or ketone, which takes precedence over alcohol
● rule 9: suffix -ene for alkenes can be placed in front of other suffixes
types of functional groups
● alkanes:
formula: R-H
suffix: -ane
example: ethane
● alkenes:
formula: R-CH=CH2
suffix: -ene
example: propene
● haloalkanes:
formula: R-X (X=halogen)
suffix: none
example: chloromethane
● alcohol:
formula: R-OH
suffix: -ol
example: ethanol
● aldehydes:
formula: R-CHO
suffix: -al
example: ethanal
● ketones:
formula: R-COR’
suffix: -one
example: propanone
● carboxylic acids:
formula: R-COOH
suffix: -oic acid
example: ethanoic acid
what is a functional group?
● an atom or group of atoms or bond in an organic molecule that is responsible for the characteristic reactions of that molecule
● always reacts in same way no matter length of hydrocarbon chain
