Aromatic Compounds PDF

Aromatic Compounds Prof. Dr. A. Süha Yalçın [email protected] Benzene and its derivatives have pleasant aromas and therefore they are called aromatic compounds. The benzene molecule is unsaturated but the double bonds present inside the benzene ring are delocalized due to bond...

Aromatic Compounds Prof. Dr. A. Süha Yalçın [email protected] Benzene and its derivatives have pleasant aromas and therefore they are called aromatic compounds. The benzene molecule is unsaturated but the double bonds present inside the benzene ring are delocalized due to bond resonance. Various aromatic compounds, which are also called arenes, are formed by condensed benzene rings. benzene  Benzene derivatives are formed by substituting different functional groups for hydrogen in the benzene molecule. Fluorobenzene Bromobenzene Chlorobenzene Nitrobenzene Isomerism in Benzene / Aromatic Compounds If there is only one substituent in benzene, there is no isomerism. If there are 2 substituents, then there are 3 isomers. These are ortho (-o), meta (-m) and para (–p). If there are 3 substituents the number of isomers will increase.  Dibromobenzene Trichlorobenzene Nitrobenzoic acid Trinitrobenzene  File:Trinitrobenzene.svg Toluene 2,4,6-trinitrooluene 2,4,6-trinitrobenzene Toluene is a water-insoluble liquid having the typical smell of paint thinners and is used as a solvent. It is an aromatic hydrocarbon which is widely used as an industrial feedstock.  + heat Toluene p-toluenesulfonic acid o-toluenesulfonic acid Used in preparation of antiseptics. o-toluenesulfonic acid Benzoic acid o-sulfimide (saccharine) Saccharine is an artificial sweetener 500 x sweeter than sugar used by diabetic patients. The meaning of saccharine is resembling that of sugar. Vinylbenzene (styrene) Polystyrene is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. Dimethyl benzenes are often called xylenes. Xylene is widely used as a solvent in different industries in a mixture of ortho, meta, para isomers. Xylene, evaporates quickly from the soil and surface water into the air and can be absorbed through the respiratory tract and through the skin.  Diphenylmethane Dichlorodiphenylethane, DDT Triphenylmethane Phenolphthalein Phenylalanine is an important essential amino acid. It turns to tyrosine in the body which is the precursor of thyroid hormones, catecholamines and melanin. Phenylalanine and another amino acid aspartic acid, is also present in the structure of aspartame which is one of the most common artificial sweeteners in use today. Compounds formed by the bonding of two or more benzene rings are called condensed ring aromatic compounds. Polycyclic aromatic hydrocarbons (PAH), which are formed as a result of the incomplete combustion of organic substances, are well known human carcinogens. At the beginning of the 20th century, the increase in the frequency of cancer in asphalt workers has revealed the cancerous effects of aromatic substances. Picric acid is an aromatic nitro compound It has been used as a military explosive, as a yellow dye, and as an antiseptic. Its highly corrosive action on the metal surfaces of shells was a disadvantage and after World War I its use declined.  Aromatic Amines Aniline Diphenylamine Triphenylamine  Sulfonamides Sulfoguanidine p-amino benzene sulfonamide Phenols are formed by bonding an -OH group to the aromatic ring. Hydroquinone is found in skin lighteners, facial and skin cleaners, facial moisturizers. It works by inhibiting the enzyme tyrosinase, which is important for the development of melanin pigment.  Aromatic Ethers Methyl phenyl ether Eugenol is a chemical compound present in several plant species and it is responsible for the flavor of cloves. In dentistry, eugenol is used as a pat: zinc oxide + eugenol as root canal sealing.  Guaiacol Butylated hydroxyanisole Guaiacol is an agent thought to have disinfectant properties and is added to foods as preservative. BHA and BHT are derivatives of guaicol which are used as additive for foods. Guaiacol is also used for vanillin synthesis. Vanillin is obtained from vanilla plant and widely used in pastry. It has two characteristic functional groups, hydroxyl and aldehyde groups.  Aromatic Aldehydes Benzaldehyde p-methoxybenzaldehyde Anise seed  Quinones are biological pigments, biochromes 1,2 naphtoquinone Red 1,4 naphtoquinone Red Yellow Yellow Alizarin(alizarin red) Vitamin K and Coenzyme Q Coenzyme Q10 Chloranil a fungicide, is tetrachlorine derivative of quinone  Aromatic Alcohols Benzyl alcohol also known as α-cresol is an aromatic alcohol with antipyretic activity. Cinnamyl alcohol is obtained from cinnamon and used in parfumery.  Aromatic esters are used as parfums. Benzyl acetate, Pear, Strawberry, Jasmine Ethyl cinnamate, Cinnamon Methyl cinnamate, Strawberry Methyl antranilate, Jasmine Mint oil  Aromatic carboxylic acids Benzoic acid and its salts are used as food preservatives. Benzoic acid is an important precursor for the synthesis of many other organic substances.  Tetracaine p-amino benzoic Tetracaine is acid (PABA) obtained from PABA. Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID). It is used to reduce pain, fever, and/or inflammation, and as an antithrombotic.