Aromatic Organic Chemistry PDF

Aromatic Organic Chemistry By Dr. Ahmed Gaber Mohammed Taha Lecturer in Organic Chemistry Faculty of Science South Valley University Aromatic Compounds  Content 1- Benzene 2- Toluene 3- phenol 4- Sulphonic acids 5- aromatic amines 6- aromatic nitro 7- A...

Aromatic Organic Chemistry By Dr. Ahmed Gaber Mohammed Taha Lecturer in Organic Chemistry Faculty of Science South Valley University Aromatic Compounds  Content 1- Benzene 2- Toluene 3- phenol 4- Sulphonic acids 5- aromatic amines 6- aromatic nitro 7- Aromatic aldehydes 8- Aromatic Ketones 9- Phenol - Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. - The word "aromatic" originates from the past grouping of molecules based on odor, before their general chemical properties were understood. The current definition of aromatic compounds does not have any relation with their odor. - Heterocycles are closely related, since at least one carbon atom of CH group is replaced by one of the heteroatoms oxygen, nitrogen, or sulfur. Examples of non- benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one nitrogen atom. Hydrocarbons without an aromatic ring are called aliphatic. -Aromatic compounds play key roles in the biochemistry of all living things. -The four aromatic amino acids histidine, phenylalanine, tryptophan, and tyrosine each serve as one of the 20 basic building-blocks of proteins. -Aromatic compounds are important in industry. Key aromatic hydrocarbons of commercial interest are benzene, toluene, ortho-xylene and para-xylene. About 35 million tonnes are produced worldwide every year. They are extracted from complex mixtures obtained by the refining of oil or by distillation of coal tar, and are used to produce a range of important chemicals and polymers, including styrene, phenol, aniline, polyester and nylon.  Benzene -Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon. -Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items Resonance of Benzene  Aromaticity 1- Organic compounds are ring-shaped and the carbon atoms are in the same plane (co-planer). 2- Organic compounds are conjugated double bond. 3- the hybridization of atoms is of the SP2 type. 4- Huckle’s law applies to it, which determines the number of electrons forming the pi-bond n = 0, 1, 2, 3,……………… 4n+2 = 6 4n+2 = 10 4n+2 = 14 4n = 6-2 = 4 n=2 n= 3 n= 4/4 = 1 Due to SP3 hybridization or not obey Huckle’s rule ? Nomenclature of benzene derivatives a) Mono- substituted benzene 1- combining the substituent prefix with the word benzene aminobenzene nitrobenzene 2- A number of mono-substituted benzene derivatives have special names : b) Di- substituted benzene 1) 2) 3) 2-bromo-3-(4-nitrophenyl)butanoic acid P-bromobenzenesulfonic acid   Preparation of benzene Zinc dust is used to reduce carbonyls, carbon-halide bonds, carbon-oxygen bonds, alkynes, and heteroatom bonds such as N-N and N-O bonds. 2- The reaction of benzoic acid and their salts with sodalime The chemical reaction of benzene and its derivatives 1- Electrophilic substitution a) Nitration b) Sulphonation c) Halogenation d) Friedel-craft alkylation e) Friedel –craft acetylation 2- addition reactions Nitration reaction Sulphonation reaction Halogenation Friedel – craft alkylation reaction Friedel – craft acylation reaction  Addition reaction of benzene Orientation in Electrophilic Aromatic Substitution Reactions 3-nitration 4- Halogantion Aldehydes and Ketones Benzaldehyde 4-hydroxyl-3-methoxy benzaldehyde Preparation of benzaldehyde dust Cycloaddition reactions  Synthesis of ketones: 1- 2- By oxidation of secondary alcohols 4- with active methylene arrylidene Carboxylic acids  Benzoic acid Salicylic acid Phthalic acid Cinnamic acid Phenyl acetic acid Reactions of carboxylic acids 1- with sodium hydroxide 2- with sodium carbonate 3- with amm.hydroxide 4- With LiAlH4 Lithium aluminum hydride 5- Esterification 6- Nitration Phenols catechol resorcinol quinol  Synthesis of phenols 1- from salicylic acid 2-from benzene 3- From aniline Reactions  Exam A) Put the right sign or the wrong sign: 1- Benzene reacted with methylchloride in the presence of sodium metal to form 2-methyl benzene only. 2- Salicaldehyde is reduced in to formylbenzene by Zinc dust. 3- Aniline compound obey Huckle’s rule. B) Toluene reacted nitric acid in the presence of sulpheric acid to form A and B. Then Toluene reacted with C to formylbenzene. Formylbenzene is oxidized in air to form D. D reacted with acetyl chloride to afford E. please write the chemical structures of the A, B, C, D, E compounds.