ADIGUN LATIFAT DEMEHIN ORE – OFE FASUYI ABIMBOLA ADEGUNSOYE ADEFEMI CHEMISTRY OF ALKANOIC ACID NAMEMATRIC NUMBER
Alkanoic acids, also know as organic carboxylic acids, contain the cabocyl group, -COOH as their functional group The most common of these are the aliphatic monocaboxylic acids which contain one carboxyl group per molecule, they form a homologous series with general formular of CnH 2n +COOH where n >O. they are sometimes called fatty acids because some of them are found in natural fats and oils. The IUPAC name of each homologue is obtained by changing the ending of the corresponding alkane to –oic acid. Dicarboxylic acids have 2 carboxyl group per molecule e.g. ethanoic acid (oxalic acid) Cis –butenedioic acid (maleic acid) 2,3 dibydroxybutanedioic acid (tartaric acid) While tricarboxylic aid have 3 carboxylic acid per molecule e.g 2- hydroxypropane – 1,2,3 – tricarboxylic acid(citric acid) Two important aromatic carboxylic acids are Benzoic acid and 2 – hydroxybenzoic acid (salicylic acid) ALKANOIC ACIDS
Structure of a carboxylic acid Carboxylate ion The 3D structure of the carboxyl group
Naming of carboxylic(alkanoic acids) Number the longest carbon chain starting with the carbon atom of the COOH functional group. Name the carbon chain. Add the suffix -oic acid Nomenclature and examples Carboxylic acids are commonly named as indicated in the table below. Although rarely used, IUPAC-recommended names also exist. For example, butyric acid (C 3 H 7 CO 2 H) is, according to IUPAC guidelines, also known as butanoic acid. IUPACbutyric acid  The carboxylate anion R-COO – is usually named with the suffix - ate, so acetic acid, for example, becomes acetate ion. In IUPAC nomenclature, carboxylic acids have an -oic acid suffix (e.g., octadecanoic acid). In common nomenclature, the suffix is usually -ic acid (e.g., stearic acid).carboxylate anionIUPAC nomenclaturecommon nomenclaturestearic acid Straight-chained, saturated carboxylic acids
Carbon atoms Common name IUPAC name Chemical formula Common location or use 15 Pentadecanoic acidCH 3 (CH 2 ) 13 COOHPentadecanoic acid 16 Palmitic acid Hexadecanoic acid CH 3 (CH 2 ) 14 COOH Palm oilPalmitic acid 17 Margaric acid Heptadecanoic acid CH 3 (CH 2 ) 15 COOHHeptadecanoic acid 18 Stearic acid Octadecanoic acid CH 3 (CH 2 ) 16 COOH Chocolate, waxes, soaps, and oils 20 Arachidic acid Icosanoic acid CH 3 (CH 2 ) 18 COOH Peanut oil
Examples of Carboxylic (Alkanoic) Acids formula longest carbon chain C-C single bonds functional group nameoccurrence HCOOHC 1 : meth-an- -COOH (oic acid) methanoic acid (formic acid) ants CH 3 COOHC 2 : eth-an- -COOH (oic acid) ethanoic acid (acetic acid) vinegar C 2 H 5 COOHC 3 : prop-an- -COOH (oic acid) propanoic acid (propionic acid) dairy products C 3 H 7 COOHC 4 : but-an- -COOH (oic acid) butanoic acid (butyric acid) rancid butter C 4 H 9 COOHC 5 : pent-an- -COOH (oic acid) pentanoic acid (valeric acid) valerian root
compoundformulamelting point ( o C)boiling point ( o C) ethanoic acidCH 3 COOH17118 ethanolCH 3 CH 2 OH ethanalCH 3 CHO ethaneCH
Properties They are very polar molecule. They form hydrogen bonds which results in their existence as dimmers. They have high boiling points due to the presence of hydrogen bonds. Their boiling point is higher than that of their corresponding alcohol. The 1 st 4 members are miscible with water while the rest are not but miscible in organic solvents. They are soluble in bases forming salts.
Chemical Properties Ethanoic acid is a fairly stable compound which is not easily decomposed by heat. It is also unaffected by all ordinary reducing agents, oxidizing agents and dehydrating agents.
Acid Properties As a weak monobasic acid, ethanoic acids shows all the usual acidic properties, this it Neutralizes bases or alkalis to form salts, known as ethanoates, and water only. Attacks strongly electropositive metals e.g. magnesium and calcium. CH 3 COOH (aq) +NaOH (aq) CH 3 COONa (aq) +H 2 O 2CH 3 COOH (aq) +Mg (s) (CH 3 COO) 2 Mg (aq) +H 2(g)
Ester Formation Ethanoic acid reacts reversibly with alkanols to form esters. For example, it reacts with ethanol when heated to produce ethyl ethanoate, CH 3 COOC 2 H 5. The reaction is catalyzed by tetraoxosulphate(vi)acid. CH 3 COOH (aq) +C 2 H 5(aq) CH 3 COOC 2 H 5(L) + H 2 O (L) Ethanoic acid alkanolester(ethylethanoates) water A carboxylate ester. R and R' denote any alkyl or aryl groupalkylaryl Esters are usually derived from an inorganic acid or organic acid in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group, and most commonly from carboxylic acids and alcohols. That is, esters are formed by condensing an acid with an alcohol.inorganic acidorganic acidalkylalkoxycarboxylic acidsalcohols condensing Esters are ubiquitous. Most naturally occurring fats and oils are the fatty acid esters of glycerol. Esters with low molecular weight are commonly used as fragrances and found in essential oils and pheromones. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important with plastics,with monomers linked by ester moietiesfatty acidglycerolessential oilspheromonesPhosphoestersDNAnitroglycerinpolyesters
Esterification Reactions EstersEsters are produced in a condensation reaction between a carboxylic (alkanoic) acid and an alkanol (alcohol). This is known as an esterification reaction. carboxylic (alkanoic) acid + alkanol (alcohol) ester + water eg, 2CH 3 COOH + CH 3 OH CH 3 COOCH 3 + H 2 O ethanoic acid + methanol methyl ethanoate + water
Uses Ethyl acetate for manufacture of nail polish remover, modelpaint, model airplaneglue.Ethyl formate for the production of rum.Odor Ethyl acetatenail polish remover modelpaintmodel airplaneEthyl formate Carboxylic acids often have strong odors, especially the volatile derivatives. Most common are acetic acid (vinegar) and butanoic acid (rancid butter). On the other hand, esters of carboxylic acids tend to have pleasant odors and many are used in perfumes. Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives. Industrially important carboxylic acids include acetic acid (component of vinegar, precursor to solvents and coatings), acrylic and methacrylic acids (precursors to polymers, adhesives), adipic acid (polymers), citric acid (beverages), ethylenediaminetetraacetic acid (chelating agent), fatty acids (coatings), maleic acid (polymers), propionic acid (food preservative), terephthalic acid (polymers)perfumesacrylic and methacrylic acidsadipic acidcitric acid ethylenediaminetetraacetic acidfatty acidsmaleic acidpropionic acid terephthalic acid
Chlorination Formation of acyl chloride:- glacial or anhydrous ethanoic acid reacts with phosphorus(v) chloride in the cold to form ethanoyl chloride, CH 3 COCL, a colourless liquid which fumes in air. Formation of chloroalkanoic acid. If chlorine is passed into boiling ethanoic acid, in the presence of sunlight, iodine or red phosphorus as the catalyst, substitution will take place in the methyl group (- CH 3 ) while the carcoxyl group (-COOH) remains intact. The product of this reaction is monochloroethanoic acid, CH 2 CLCOOH. If the reaction is prolonged, further chlorination will occur to produce the Dichloroethanoic acid, CHCl 2 COOH, and Trichloroethanoic acid, CCl 3 COOH, Successively Bromine reacts with ethanoic acid in a similar way as chlorine, though less readily.
Decarboxylation reaction If sodium ethanoate is heated strongly with soda-lime methane will be produced together with carbon (iv) oxide CH 3 COONa (aq) CH 4(g) +CO 2(g)
Reduction Alkanoic acids can be reduced to primary alkanols, using litium tetrahydridoaluminate, LiAlH 4, as reducing agent to supply the hydrogen. CH 3 COOH (aq )+4[H]CH 3 CH 2 OH (l) +H 2 O (l)
Uses Ethanoic acid is used is making compounds like i. Ethenyl ethanoate (vinyl acetate) which is used in vinyl resins ii. Ethanoic anhydride which is used in asipirin; iii.Cellulose ethanoate (cellulose acetate) which is used for packing in varnishes, in the filter tips of cigarettes as well as in the manufacture of synthetic fibres like rayon and artificial silk; iv.Propanone (acetones) and v.Various dyes vi.Ethanoic acid is also an important organic solvent. It is used in the food industry as vinegar, for preserving and flavouring food. Sometimes, it is also used for coagulating rubber latex.