|
A summary guide to the Structure and Naming-Nomenclature of Functional Groups and Homologous Series in Organic Chemistry GCE-AS-A2-IB ADVANCED LEVEL ORGANIC CHEMISTRY Allow time for graphic images/diagrams/pictures to download © Dr W P Brown Examples of functional groups, homologous series, general formula, displayed formula, graphic formula, molecular formula, skeletal formula, structural formula, empirical formula etc. are all explained with links to more examples of structure and naming and quizzes and reaction equations, reaction conditions and mechanisms. allow time for graphic images/pictures to download organic
identity tests * A functional group is an atom or combination of atoms which gives an organic molecule its distinctive and characteristic chemistry. The term 'functional' group is linked to the concept of a homologous series. A homologous series is a group of molecules with the same general formula and the same functional group. They have similar physical and chemical properties (albeit with trends e.g. increasing boiling point with increasing carbon chain length). The terms higher/lower refer to a larger/smaller or longer/shorter carbon chain. Alkanes, Alkenes, Alkynes, Aromatics-arenes, Halogenoalkanes, Alcohols (prim/sec/tert), Phenols, Ethers, Aldehydes, Ketones, Carboxylic acids, Acid chlorides, Acid Anhydrides, Amides, Esters, Nitriles, Amines (prim/tert/sec), Quaternary ammonium salts, Nitro-aromatics, Diazonium salts and dyes, Sulphonic (sulfonic) acids, and more examples, due to the variety possible, of Aromatic Compounds and Organic Nitrogen Compounds on separate web pages. Other links: Organic Reaction Mechanisms Note on structure 'styles' of representation An empirical formula is the simplest whole number ratio of the atoms in a compound as found by experiment i.e. chemical analysis. It gives no structural information and may or may not be the same as the molecular formula e.g. CH4 is both the empirical formula and the molecular formula of methane. However, the molecular formula of the butane molecule is C4H10 but its empirical formula is C2H5. The molecular formula of a glucose sugar molecule is C6H12O6 but its empirical formula is only CH2O ! A molecular formula e.g. C3H6O2, gives a summary of all the atoms in the molecule, but gives no information on structure. A
structural
formula - minimal/abbreviated/shortened e.g. A
structural
formula - full/displayed/graphical e.g.
A
structural formula with full
3D spatial representation e.g. A skeletal formula e.g.
A general formula sums up the formulae a series of compounds e.g. a homologous series of chemically similar compounds with closely related formulae e.g. the only difference may be more/less -CH2- groupings in the carbon longest chain. There are many examples quoted throughout the rest of this page in the style CxHyOz etc. where x, y and z are variables like 1, 2, 3 etc. but they related for a particular homologous series e.g. for saturated non cyclo alkanes the general formula is CnH2n+2 for alkanes, so that n=1 generates the formula for methane CH4 and n=5 generates the formula for pentane C5H12 etc. and ..... CnH2n+1COOH is the general formula for monocarboxylic acids, so that n=0 generates the formula for methanoic acid HCOOH and n=4 generates the formula for pentanoic acid CH3CH2CH2CH2COOH (so do not assume n always indicates the total carbon atoms in a molecule!). However in all cases, the IUPAC systematic name is derived from the longest carbon chain, so both meth... (for one carbon) and pent... (for five carbons) occur in the names of the examples above.
FUNCTIONAL GROUPS and HOMOLOGOUS SERIES nomenclature, structure and representation in pictures-graphics ALKANES or cycloalkanes HYDROCARBONS (saturated) …ANE, e.g. ALKANES, saturated hydrocarbons i.e. no double or triple bonds. They can be linear, branched, cyclo, substituted etc. (see later - haloalkanes etc.) …
Exemplar homologous series: CnH2n+2 for non-cyclo alkanes (n=1,2,3 etc.) and CnH2n for cycloalkanes (n=3,4,5 etc.) isomeric with non-cyclo alkenes further Notes and examples of the structure and nomenclature of alkanes Multiple choice Quiz on naming alkanes * Type in an alkane name Quiz
ALKENE HYDROCARBONS (unsaturated) …ENE, ALKENES, unsaturated hydrocarbons with a carbon=carbon C=C double bond functional group (ene) They can have more than one C=C, be linear, branched, cyclo …
further Notes and examples of the structure and nomenclature of alkenes Multiple choice Quiz on naming alkenes * Type in an alkene name Quiz Exemplar homologous series: CnH2n for non-cyclo alkenes (n=2,3 etc. with one C=C bond) isomeric with cycloalkanes and CnH2n-2 for cycloalkenes (n=3,4,5 etc., and with one C=C bond)
ALKYNE HYDROCARBONS (unsaturated) …YNE
e.g. ALKYNES, unsaturated hydrocarbons with a
C
Exemplar homologous series: CnH2n-2 for non-cyclo alkynes (with one triple bond)
AROMATIC HYDROCARBONS (unsaturated) 'ARENES' are aromatic hydrocarbons with at least one benzene ring functional group e.g. …
further Notes and examples of the structure and nomenclature of aromatic compounds further Notes and examples of aromatics * Type in an alkane name Quiz
aliphatic/aromatic HALOGEN COMPOUNDS Aliphatic: HALO… e.g. HALOGENOALKANES (HALOALKANES) C-X halogen functional group where X = F fluoro…, Cl chloro.., Br bromo… or I iodo… X is named as a prefix substituent in any type of organic molecule from alkanes to carboxylic acids.
or phenylchloromethane, which can also be classified as an aromatic compound BUT the halogen is not attached directly to the benzene ring so it is not an aryl halide) Exemplar homologous series: CnH2n+1X for non-cyclo saturated halogenoalkanes (X=F,Cl,Br,I and n=1,2,3 etc.) and CnH2n-1X for saturated cyclohalogenoalkanes (n=3,4,5 etc. with one C-X bond)
Multiple choice Quiz on naming haloalkanes * Type in a haloalkane name Quiz NOTE: Aromatic HALO ... ARENES (aromatic halogen compounds) have the halogen atom directly attached to the benzene ring.
ALCOHOLS (aliphatic, alkanols) and PHENOLS (aromatic) Aliphatic …OH hydroxy functional group (ol) e.g. ALIPHATIC ALCOHOLS. Aliphatic alcohols are classified as primary, secondary and tertiary. You can have diols, triols etc, with 2,3 etc, OH groups. If there is a 'higher ranking' functional group in the molecule the substituent OH is called by the prefix 'hydroxy' see * examples. Primary aliphatic alcohols R-OH where R is alkyl
Secondary aliphatic alcohols R-CH(OH)-R' where R or R' are both alkyl (or aryl):
Tertiary aliphatic alcohols RR'R"C-OH where R,R' or R" are all alkyl (or aryl):
Exemplar homologous series: CnH2n+1OH for saturated non-cyclic aliphatic alcohols (n=1,2,3 etc.) or the less informative CnH2n+2O isomeric with aliphatic non-cyclo ethers and CnH2n-1OH for cycloalcohols (n=3,4,5 etc. with one C-OH) Notes and examples of the structure and nomenclature of aliphatic alcohols/alkanols **further Notes and examples on types of alcohols and phenols ** linked to notes on oxidation of alcohols to aldehydes, ketones and carboxylic acids Multiple choice Quiz on naming alcohols * Type in an alcohol name Quiz AROMATIC PHENOLS ROH, R=aryl only, when the -OH functional group is attached directly to a benzene ring the molecule is called a phenol. If there is a 'higher ranking' functional group in the molecule the substituent OH is called by the prefix 'hydroxy' see * example.
Alkyl/aryl…OXY…alkane/arene e.g. ETHERS which have the C-O-C linkage. The smaller carbon chain with the oxygen atom, is given the prefix in the name alkyl/aryl..oxy…ane (alkyl-O- groups like CH3-O- are called alkoxy groups).
Exemplar homologous series: CxH2x+1-O-CyH2y+1 for saturated non-cyclo ethers (x or y =1,2,3 etc.) or the less informative CnH2n+2O (n=2,3,4 etc.) isomeric with non-cyclo aliphatic alcohols or CnH2nO for cycloethers (n=2,3,4 etc. with one C-O-C linkage, non shown at the moment) further Notes and examples of ethers and isomeric alcohols
ALDEHYDES and KETONES (a group of carbonyl compounds) …AL e.g. ALDEHYDES have the -CHO functional group at the end of a carbon chain e.g.
Exemplar homologous series: CnH2n+1CHO for aliphatic aldehydes (n=0,1,2 etc.) or the less in formative CmH2mO (m=1,2,3 etc.) isomeric with ketones and saturated cyclic aliphatic ethers further Notes and examples of the structure and nomenclature of aldehydes multiple choice Quiz on naming aldehydes/ketones * type in name Quiz on naming aldehydes/ ketones …ONE e.g. KETONES have the C-CO-C functional group linkage within the carbon chain:
Exemplar homologous series: CxHxn+1-CO-CyH2y+1 for aliphatic ketones (x or y = 1,2,3, etc.) or the less informative CnH2nO (n=3,4,5 etc.) isomeric with aldehydes and saturated cyclic aliphatic ethers further Notes and examples of the structure and nomenclature of ketones multiple choice Quiz on naming aldehydes/ ketones * type in name Quiz on naming aldehydes/ ketones
CARBOXYLIC ACIDS …OIC ACID e.g. CARBOXYLIC ACIDS with the -COOH functional group, substituents quoted as prefixes (…dioic if 2 -COOH groups) e.g. aliphatic carboxylic acids
* examples of a dicarboxylic acids If there is a 'higher ranking' functional group in the molecule the substituent OH/NH2 is called by the prefix 'hydroxy/amino see * examples. Exemplar homologous series: CnH2n+1COOH for saturated aliphatic mono carboxylic acids (n=0,1,2,3 etc.) or the less informative CnH2nO2 (n=1,2,3,4 etc.) isomeric with aliphatic esters aromatic carboxylic acids (-COOH directly attached to the ring)
(sometimes carboxylic rather than oic is used e.g. the dicarboxylic acids of benzene) further Notes and examples of the structure and nomenclature of carboxylic acids and their derivatives m/c QUIZ on naming RCOOH acids/derivatives * Type in name QUIZ on naming RCOOH acids/derivatives
ACID ANHYDRIDES …OIC ANHYDRIDE e.g. CARBOXYLIC ACID ANHYDRIDES with the RCO-O-RCO linkage e.g.
Exemplar homologous series: (CnH2n+1CO)2O derived from aliphatic mono carboxylic acids (n=2,3 etc.) further Notes and examples of the structure and nomenclature of carboxylic acids and their derivatives m/c QUIZ on naming RCOOH acids/derivatives * Type in name QUIZ on naming RCOOH acids/derivatives
…OYL CHLORIDE e.g. CARBOXYLIC ACID or ACYL CHLORIDES with the -COCl functional group e.g.
Exemplar homologous series: CnH2n+1COCl derived from aliphatic mono carboxylic acid chlorides (n=1,2,3 etc.) further Notes and examples of the structure and nomenclature of carboxylic acids and their derivatives m/c QUIZ on naming RCOOH acids/derivatives * Type in name QUIZ on naming RCOOH acids/derivatives
ACID AMIDES …AMIDE e.g. CARBOXYLIC ACID AMIDES with the -CONH2 functional group e.g.
Exemplar homologous series: CnH2n+1CONH2 derived from aliphatic mono carboxylic acid amides (n=0,1,2,3 etc.) further Notes and examples of the structure and nomenclature of carboxylic acids and their derivatives and also other organic nitrogen compounds m/c QUIZ on naming RCOOH acids/derivatives * Type in name QUIZ on naming RCOOH acids/derivatives
alkyl/aryl …OATE e.g. ESTERS of CARBOXYLIC ACIDS derived from ALCOHOLS or PHENOLS. Esters have the -COOC- linkage:
Exemplar homologous series: CxH2x+1-COO-CyH2y+1 simple saturated aliphatic esters (x=0,1,2, etc. and y=1,2,3 etc.) or the less informative CnH2nO2 (n=2,3,4 etc.) isomeric with carboxylic acids further Notes and examples of the structure and nomenclature of carboxylic acids and their derivatives m/c QUIZ on naming RCOOH acids/derivatives * Type in name QUIZ on naming RCOOH acids/derivatives
The nitrile functional group consists of a carbon to nitrogen triple bond. The name is based on the longest carbon chain, including the C of the nitrile group e.g. methanenitrile, ethanenitrile, propanenitrile, Exemplar homologous series: CnH2n+1CN derived from aliphatic mono carboxylic acid chlorides (n=0,1,2,3 etc.) further Notes and examples of the structure and nomenclature of carboxylic acids and their derivatives and also other organic nitrogen compounds
PRIMARY AMINES have two hydrogen atoms and one alkyl or aryl group attached to the nitrogen to form the amine or amino group -NH2. ALIPHATIC: methylamine (aminomethane),
ethylamine (aminoethane),
Exemplar homologous series: CnH2n+1NH2 for saturated mono primary amines (n=1,2,3 etc.) SECONDARY AMINES have one hydrogen atom and two alkyl or aryl groups attached to the nitrogen ALIPHATIC: dimethylamine,
ethylmethylamine,
diethylamine, TERTIARY AMINES have no hydrogen atom and three alkyl or aryl groups attached to the nitrogen ALIPHATIC: trimethylamine,
ethyldimethylamine,
diethylmethylamine,
further examples of the structure and nomenclature of organic nitrogen compounds
QUATERNARY AMMONIUM SALTS If all for hydrogens of an ammonium ion are replaced with alkyl or aryl groups then an ionic quaternary salt is formed. e.g. the simplest is tetramethylammonium chloride, (CH3)4N+ Cl-
NITRO-AROMATIC COMPOUNDS These have the nitro -NO2 group directly attached to the ring e.g. nitrobenzene,
2-methylnitrobenzene
or 1-methyl-2-nitrobenzene, and also other organic nitrogen compounds
DIAZONIUM SALTS and AZO DYES Diazonium salts are formed when primary aromatic amines reaction with nitrous acid The diazonium cation has a nitrogen - nitrogen triple bond system directly attached to the benzene ring e.g. (1) (2) In alkaline solution these diazonium salts couple with phenols and aromatic amines to form azo dyes which have benzene rings linked with an azo -N=N- bond system e.g. reacting (1) with phenol gives reacting (2) with phenylamine gives and also other organic nitrogen compounds
SULPHONIC ACIDS These molecules have a strongly mono-basic acidic group -SO2OH directly attached to the benzene ring e.g. benzenesulphonic acid,
2-, 3- or
4-methylbenzenesulphonic acid,
GENERAL
* Copyright © Dr W P Brown 2000-2008 All rights reserved including the revision notes pages, quizzes, worksheets etc. * Doc Brown's Chemistry Clinic * www.docbrown.info/ * |
same price to you, but helps support the site!
or
gives
a 'limited' structure of a molecule but
unambiguous in terms of interpreting ALL atom-atom links and no/some individual bonds
may be shown.
where
all the individual atoms and bonds are shown. However it can be acceptable
to show some side-chain groups in an abbreviated form e.g. methylpropane
where the
side-chain methyl group may be written in the abbreviated form, but take car in
exams!
which
shows the shape of the molecule and implies bond angles (in this case all
are 109o).
in which no H atoms bonded
to carbon atoms are shown, the lines represent either carbon-carbon bonds
(single, double or triple), but other lines are needed to show bonds to
other atoms which are NOT carbon or hydrogen e.g. C-Cl in 
and
hydrogen atoms are shown if they are bonded to non-carbon atoms e.g. the
-OH in
.
butane,
pentylcyclohexane,
cyclopropane
2,2-dimethylpropane,
2,2,3-trimethylbutane
pent-1-ene,
cyclobuta-1,3-diene
or
buta-1,3-diene,
C triple bond
functional group (yne) e.g.
ethyne, and
propyne
or
benzene,
or
methylbenzene
chloromethane,
bromoethane,
dichlorodifluoromethane
iodocyclohexane
1,2-dibromocyclopentane,
chloromethylbenzene
1,4-dichlorobenzene,
chloro-2-methylbenzene
ethan-1,2-diol
or
3-methylbutan-1-ol
4-hydroxybutanoic
acid*
propan-2-ol,
cyclohexanol,
pentan-3-ol
cyclopentanol,
2-hydroxybutanoic
acid*
or
2-methylpropan-2-ol,
2-methylbutan-2-ol
or 
3-methylpentan-1-ol
or
or
phenol,
2-chlorophenol,
3-methylphenol
2,5-dichloro-4-methylphenol,
3-hydroxybenzoic
acid* 
methoxymethane,
methoxyethane,
2-ethoxypropane
ethoxyethane,
2-methoxypropane,
ethanal,
propanal,
or
2-methylpropanal
butanal,
pentanal,
2-methylbutanal
propanone,
or
butanone,
pentan-2-one
or 
pentan-3-one
methanoic
acid,
propanoic acid,
*aminoethanoic
acid
2-methylpropanoic
acid,
*2-hydroxybutanoic
acid
pentanoic
acid, 
*
ethanedioic
acid
2-ethanoylhydroxybenzoic
acid (Aspirin!)
2-chlorobenzoic acid,
* benzene-1,2-dicarboxylic
acid
or
ethanoic
anhydride
or
pentanoic
anhydride
or
propanoyl
chloride, 
butanoyl
chloride
or
pentanoyl
chloride,
benzoyl chloride
or
ethanamide,
propanamide
butanamide,
pentanamide,
benzamide
methyl
methanoate, 
propyl
propanoate
ethyl
propanoate, 
ethyl
benzoate
,
,
,
,
,
, 
,
,
,
,
, 
,
,
,
, 
,
,
,
,
,
,
,
,
,
,
;
1,3-dinitrobenzene, 
from
phenylamine+
from
4-methylphenylamine
,(or
benzenesulfonic acid)
, 
,
(or
....sulfonic acid)
