Valence of elements in organic compounds: C = always tetravalent N = trivalent O = bivalent S = bivalent H = monovalent Halogens = monovalent Classification of organic compounds: 1. Hydrocarbons 2. Derivatives of hydrocarbons
Hydrocarbons - overview 1) Aliphatic (acyclic) hydrocarbons a) saturated - alkanes → ending: -ane (methane) b) unsaturated - alkenes → ending: -ene (ethene) - alkadienes → ending: -diene (butadiene) - alkynes → ending: -yne (ethyne) 2) Cyclic hydrocarbons a)alicyclic saturated - cycloalkanes → cyclo……ane (cyclopropane) b) alicyclic unsaturated – cycloalkenes and cycloalkadienes c) aromatic hydrocarbons = arens (benzene and its derivatives )
Important heterocyclic compounds NITROGEN in the cycle pyrrole pyridine pyrimidine purine indole imidazole OXYGEN in the cycle furane tetrahydrofurane pyrane tetrahydropyrane
DERIVATIVES OF HYDROCARBONS The name of the compound is derived from the name of the basic unbranched hydrocarbon principal functional group type of the derivative suffix other functional groups → expressed by special prefixes + locants
Rules for naming of organic compounds ●To find the longest unbranched chain containing the most functional groups or to find the longest unbranched chain containing the most double bonds or to find the longest unbranched chain The main functional groups, multiple bonds and the other substituents must obtain the lowest number locants as possible Main functional group is the group with the highest position in the „Table of functional groups“ ordering the groups according to their „nomenclature importance“.
Derivatives of hydrocarbons ALCOHOLS R-OH (R = alkyl) Suffix: -ol (methanol, ethanol, …..) or alkyl + alcohol (ethyl alcohol) Suffix: -diol (ethane-1,2-diol) or glycol (ethylene glycol) Primary, secondary, tertiary alcohols PHENOLS Ar-OH (Ar = aryl) Common (trivial) names (phenol, pyrocatechol, resorcinol) THIOLS (MERCAPTANES) R-SH Suffix: -thiol (methanethiol) or Alkyl + mercaptan (methyl mercaptan)
ETHERS R 1 -O-R 2 (R = alkyl or aryl) Alkyl ether (ethyl methyl ether) ! alphabetic order ! or alkoxy + name of hydrocarbon (methoxyethane) i.e. diethyl ether (common name „ether“) SULFIDES R 1 -S-R 2 (R = alkyl or aryl) Alkyl sulfide (ethyl methyl sulfide) ALDEHYDES R-CHO (R = H, alkyl or aryl) Suffix: -al (methanal, ethanal, propanal, …) ! Trivial name of corresponding carboxylic acid + aldehyde (formic acid → formaldehyde, acetic acid → acetaldehyde) Cycloalkane carbaldehyde
KETONES R 1 -CO-R 2 (R = alkyl or aryl) Suffix: -one (propanone, butanone,..) or alkyl + ketone (dimethyl ketone) ! Trivial names (acetone) ! Diketones derived from arens: -quinone (1,4-benzoquinone) AMINES are derived from ammonia: H(s) replaced by alkyl(s) a) primary amines R-NH 2 Alkylamine (methylamine) b) secondary amines R 1 -NH-R 2 Alkyl 1 (alkyl 2 )amine e. g. ethyl(methyl)amine ! alphabetic order ! N-alkylhydrocarbonamine (N-methylethanamine) c) tertiary amines R 1 -NR 2 -R 3 Alkyl 1 (alkyl 2 )alkyl 3 amine (trimethylamine)
Organic reactions Addition reactions: 2 or more molecules combine to form a larger one Hydration: addition of water i. e. fumarate + H 2 O → malate Hydrogenation: addition of H 2 usually to unsaturated organic compounds i.e. CH 2 =CH 2 + H 2 → CH 3 -CH 3 Unsaturated fatty acids (in oils) can be converted to solid fats (margarine) Halogen addition ● Elimination reactions: Dehydration = loss of H 2 O from reacting molecule i.e. conversion of alcohols to ethers 2 R-OH → R-O-R + H 2 O i.e. conversion of carboxylic acids to anhydrides 2 R-COOH → R-CO-O-CO-R + H 2 O
Substitution reactions – a functional group in a particular compound is replaced by another group i.e. carboxylic acids → chlorides, amides of carboxylic acids Rearrangement reactions – position of functional group is rearranged to give a structural isomer of the original molecule i.e. citrate → isocitrate ● Redox reactions: many redox reactions in organic chemistry have coupling mechanism involving free radicals intermediates (peroxides, superoxides O 2 - )
Your consent to our cookies if you continue to use this website.