Advanced level organic chemistry index of pages on specific sets of isomers of a given molecular formula
 

Doc Brown's pre-university/college Advanced Level Organic Chemistry

ISOMERISM - INDEX of the structure and names of isomers of a given molecular formula

[Author ©  Dr WP Brown PhD: Doc Brown's advanced level organic chemistry exam revision notes suitable for students of UK advanced level chemistry courses, IB advanced chemistry & US K12 grades 11-12 and AP honors chemistry courses: Molecular spectroscopy and analysing the INDEX of isomers of particular molecular formula [isomerism page updated Feb 9th 2026 *]

PART 14.7 index of pages on specific sets of isomers

Isomerism occurs when at least two molecules of the same molecular formula have some structural difference, sufficient to make them unique molecules.

The isomers may be very similar or very different in terms of their physical and chemical properties - this idea can be explored in more detail via my general isomerism index.

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All My pre-university Advanced Level Organic Chemistry Notes

INDEX of sets of isomers of organic compounds of a given molecular formula

The molecular formula summarises the actual number of atoms of each element in the molecule.

n = number of carbon atoms in a general organic molecular formula.

Mr = relative molecular mass of the molecule

Ar = relative atomic masses values used in isomerism sections

C = 12.01,  H = 1.01,  N = 14.00,  O = 16.00,

F = 19.00, Cl = 35.45,  Br = 79.90,  I = 126.90

Types of isomerism if applicable (see isomerism summary at the end of the page)

Structural isomerism includes carbon chain variation (usually need a minimum of 4 C atoms), change in position of a substituent or functional group and functional group isomerism where the atoms have a different configuration, usually with significant differences in chemical and physical properties.

Stereoisomerism is where molecules have the same basic constitutional structural formula, but isomers differ in the 2D/3D arrangement of the atoms.

E/Z stereoisomerism was called 'geometrical isomerism' e.g. cis and trans isomers of alkenes or disubstituted cycloalkanes where there are spatial variations that are not mirror images and not super imposable.

R/S stereoisomerism was called 'optical isomerism', the pairs of isomers are called enantiomers which are 3D non-superimposable mirror image forms of the molecule.

The molecule must have a chiral centre (a stereocentre), that is an asymmetric carbon atom with four different atoms/groups attached to it.

Some of the isomers described may be highly reactive and very thermodynamically unstable e.g. due to weak highly strained bonds and some may not even exist at all (except theoretically of course!).

Spectra can be used to distinguish between isomers of a given molecular formula.

Index of all spectroscopy pages

INDEX OF ALL MY ISOMER ANALYSIS PAGES for a given molecular formula

Isomers of aliphatic alkanes of molecular CnH2n+2

(saturated non-cyclic open chain aliphatic compounds, no isomers possible for CH4, C2H6 or C3H8)

Isomers of molecular formula C4H10 (Mr = 58)

Isomers of molecular formula C5H12 (Mr = 72)

Isomers of molecular formula C6H14 (Mr = 86)

Isomers of molecular formula C7H16 (Mr = 100)

Isomers of molecular formula C8H18 (Mr = 114)

Isomers of molecular formula C9H20 (Mr = 128)

Isomers of molecular formula C10H22 (Mr = 142)

 

Isomers of non-cyclic aliphatic alkenes and alicyclic cycloalkanes of molecular formula CnH2n

(unsaturated non-cyclic and saturated cyclic aliphatic compounds, no isomers possible for C2H4)

Isomers of molecular formula C3H6 (Mr = 42)

Isomers of molecular formula C4H8 (Mr = 56)

Isomers of molecular formula C5H10 (Mr =70)

Isomers of molecular formula C6H12 (Mr = 84)

Isomers of molecular formula C7H14 (Mr = 98)

 

Isomers of other hydrocarbon molecules

(unsaturated non-cyclic and unsaturated cyclic aliphatic compounds, aromatic compounds, but no isomers possible for molecular formula C2H2)

Isomers of molecular formula C3H4 (Mr = 40)

Isomers of molecular formula C4H4 (Mr = 52)

Isomers of molecular formula C4H6 (Mr = 54)

Isomers of molecular formula C5H6 (Mr = 66)

Isomers of molecular formula C5H8 (Mr = 68)

Isomers of molecular formula C6H6 (Mr = 78) includes aromatic benzene

Isomers of molecular formula C6H8 (Mr = 80)

Isomers of molecular formula C6H10 (Mr = 82)

Isomers of molecular formula C7H8 (Mr = 92) includes aromatic methylbenzene

 

Isomers of aliphatic halogen compounds (X = halogen atom)

Saturated/unsaturated open chain compounds and saturated/unsaturated cyclic compounds

(including examples of CnH2n-1X for n>2,  CnH2n+1X for n>2

Isomers of molecular formula C2H2X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C2H4X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C2H3X3  (where X = F, Cl, Br or I)

Isomers of molecular formula C2H2X4  (where X = F, Cl, Br or I)

Isomers of molecular formula C3H2X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C3H3X  (where X = F, Cl, Br or I)

Isomers of molecular formula C3H4X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C3H5X  (where X = F, Cl, Br or I)

Isomers of molecular formula C3H6X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C3H7X  (where X = F, Cl, Br or I)

Isomers of molecular formula C4H3X  (where X = F, Cl, Br or I)

Isomers of molecular formula C4H5X  (where X = F, Cl, Br or I)

Isomers of molecular formula C4H7X  (where X = F, Cl, Br or I)

Isomers of molecular formula C4H9X  (where X = F, Cl, Br or I)

Isomers of molecular formula C4H8X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C5H5X  (where X = F, Cl, Br or I)

Isomers of molecular formula C5H7X  (where X = F, Cl, Br or I)

Isomers of molecular formula C5H9X  (where X = F, Cl, Br or I)

Isomers of molecular formula C5H10X2  (where X = F, Cl, Br or I)

Isomers of molecular formula C5H11X  (where X = F, Cl, Br or I)

Isomers of molecular formula C6H13X  (where X = F, Cl, Br or I)

See also aromatic halogen compounds

 

Isomers of non-cyclic saturated alcohols and ethers of molecular formula CnH2n+2O

(a variety of open chain oxygenated saturated aliphatic compounds)

Isomers of molecular formula C2H6O (Mr = 46)

Isomers of molecular formula C3H8O (Mr = 60)

Isomers of molecular formula C4H10O (Mr = 74)

Isomers of molecular formula C5H12O (Mr = 88)

 

Isomers of aldehydes, ketones, enols, cyclic ethers and epoxy compounds etc.

e.g. of formula CnH2nO where n > 1

Isomers of molecular formula C2H4O (Mr = 44)

Isomers of molecular formula C3H6O (Mr = 58)

Isomers of molecular formula C4H8O (Mr = 72)

 

Isomers of aliphatic carboxylic acids, esters, hydroxy-aldehydes/ketones of molecular formula CnH2nO2

(a variety of oxygenated aliphatic compounds including alicyclic and heterocyclic ring compounds)

Isomers of molecular formula C2H4O2 (Mr = 60)

Isomers of molecular formula C3H6O2 (Mr = 74)

Isomers of molecular formula C4H8O2 (Mr = 88)

Isomers of molecular formula C5H10O2 (Mr = 102)

Isomers of molecular formula C6H12O2 (Mr = 116)

Isomers of molecular formula C7H14O2 (Mr = 130)

 

Selected isomers of molecular formula CnH2n+2O2

Isomers of molecular formula C2H6O2 (Mr = 62)

Isomers of molecular formula C3H8O2 (Mr = 76)

 

Selected isomers of some substituted aliphatic carboxylic acids, esters, aldehydes and ketones

Selected isomers of C3H5XO2 (X = F, Cl, Br, I)

 

Selected isomers of aliphatic amine compounds

Amines of molecular formula C2H7N and C3H9N

Amines of molecular formula C4H11N

 

Selected isomers of aromatic (substituted benzene ring) compounds of varied molecular formula

(a variety of substituted benzene ring compounds)

Isomers of molecular formula C7H7X  (where X = F, Cl, Br or I)

Isomers of molecular formula C7H8O (Mr = 108)

Isomers of molecular formula C7H7NO2 (Mr = 137)

Isomers of molecular formula C8H10 (arenes of Mr = 106)

Isomers of molecular formula C8H8O2 (Mr = 136)

Isomers of molecular formula C9H12 (arenes of Mr = 120)

Isomers of molecular formula C10H14 (arenes of Mr = 134)

 

Selected isomers of other C, H and O compounds

Isomers of molecular formula C2H2O (Mr = 42)

Isomers of molecular formula C2H2O2 (Mr = 58)

Isomers of molecular formula C3H4O (Mr = 56)

Associated links

All my advanced A level isomerism and stereochemistry notes

Isomerism: general introduction, structural isomerism - chain, positional, functional group, tautomerism

Stereoisomerism: general definition, priority rules, E/Z isomerism (cis/trans 'geometric' isomerism)

Stereoisomerism - R/S ('optical') isomerism - definition and examples explained

All my Advanced A Level Organic Chemistry Notes

Pages on the nomenclature and molecular structure of homologous series including selected isomers

The molecular structure and naming of ALKANES

The molecular structure and naming of ALKENES

The molecular structure and naming of HALOGENOALKANES (haloalkanes)

The molecular structure and naming of aliphatic ALCOHOLS including isomeric ethers

The molecular structure and Naming of ALDEHYDES and KETONES

The molecular structure and naming of CARBOXYLIC ACIDS and DERIVATIVES, including isomers

The molecular structure & Naming of AROMATIC Compounds, including isomers

Pages on the general chemistry of homologous series including selected isomers

INDEX of ALL revision notes on the chemistry of ALKANES and the petrochemical industry

INDEX of ALL revision notes on the chemistry ALKENES including reactions and polymers

INDEX of ALL revision notes on the chemistry of HALOGENOALKANES (haloalkanes)

INDEX of ALL revision notes on the chemistry of ALCOHOLS (and mention of ethers)

INDEX of ALL revision notes on the chemistry of ALDEHYDES and KETONES

INDEX of ALL revision notes on the chemistry of CARBOXYLIC ACIDS and DERIVATIVES

INDEX of ALL revision notes on the chemistry of AROMATIC COMPOUNDS

INDEX of ALL revision notes on the chemistry of ORGANIC NITROGEN COMPOUNDS

Spectroscopy - a means of investigating molecular structure and sorting out isomers

Index of all spectroscopy pages and introduction to the interaction of emr with matter and calculations

Introduction to mass spectrometry

Index of mass spectroscopy notes - examples of mass spectrometry of organic compounds

Index of infrared spectroscopy notes - analysis of infrared spectra of organic compounds

Index of nuclear magnetic resonance spectroscopy 1H NMR spectra of organic compounds

Index of nuclear magnetic resonance spectroscopy 13C NMR spectra of organic compounds

A summary chart of isomerism

index for all isomerism pages

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Associated organic chemistry links

[SEARCH BOX]

 All my advanced level isomerism chemistry notes

 The chemistry of ALKANES and the petrochemical industry

 The chemistry of ALKENES

 The chemistry of organic HALOGEN compounds

 The chemistry of ALCOHOLS

 The chemistry of ALDEHYDES and KETONES

 The chemistry of CARBOXYLIC ACIDS, ESTERS and other derivatives

 The chemistry of ORGANIC-NITROGEN compounds

 The chemistry of AROMATIC COMPOUNDS

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