ORGANIC CHEMISTRY AND UNIT PROCESS ENROLLMENT NO.NAME PATEL NISHIT PATEL RAHUL PATEL SAGAR PATEL VASHISHTHA PATEL VISHAL

 Belong to a homologous series of organic compounds similar to alkanes, alkenes and alcohols  The hydrocarbon chains contain the functional group -COOH (carbonyl group) What are Carboxylic Acids? Structural Formula Chemical Formula CH 3 COOH or CH 3 CO 2 H =

Naming the Carboxylic Acids  Methanoic acid  Total of one carbon atom (meth- )  C 0 H 1 COOH  Ethanoic acid  Total of two carbons atoms (eth-)  C 1 H 3 COOH  Propanoic acid  Total of three carbon atoms (propan-)  C 2 H 5 COOH *Take note of the functional group’s location, highlighted by the dotted box

 Replace the ‘e’ with ‘oic acid’ at the end of the name of the hydrocarbon Example: Naming Carboxylic Acids H H H C C H H H ethane H O H C C O H H ethanoic acid

IUPAC nomenclature for carboxylic acids: parent chain = longest, continuous carbon chain that contains the carboxyl group  alkane, drop –e, add –oic acid HCOOHmethanoic acid CH 3 CO 2 Hethanoic acid CH 3 CH 2 CO 2 Hpropanoic acid CH 3 CH 3 CHCOOH2-methylpropanoic acid Br CH 3 CH 2 CHCO 2 H2-bromobutanoic acid

dicarboxylic acids: HOOC-COOHoxalic acid HO 2 C-CH 2 -CO 2 H malonic acid HO 2 C-CH 2 CH 2 -CO 2 H succinic acid HO 2 C-CH 2 CH 2 CH 2 -CO 2 glutaric acid HOOC-(CH 2 ) 4 -COOHadipic acid HOOC-(CH 2 ) 5 -COOHpimelic acid

Carboxylic acids, syntheses: 1.oxidation of primary alcohols RCH 2 OH + K 2 Cr 2 O 7  RCOOH 2.oxidation of arenes ArR + KMnO 4, heat  ArCOOH 3.carbonation of Grignard reagents RMgX + CO 2  RCO 2 MgX + H +  RCOOH 4.hydrolysis of nitriles RCN + H 2 O, H +, heat  RCOOH

1.oxidation of 1 o alcohols: CH 3 CH 2 CH 2 CH 2 -OH + CrO 3  CH 3 CH 2 CH 2 CO 2 H n-butyl alcohol butyric acid 1-butanol butanoic acid CH 3 CH 3 CH 3 CHCH 2 -OH + KMnO 4  CH 3 CHCOOH isobutyl alcohol isobutyric acid 2-methyl-1-propanol` 2-methylpropanoic acid

2.oxidation of arenes: note: aromatic acids only!

3.carbonation of Grignard reagent: R-X RMgXRCO 2 MgX RCOOH Increases the carbon chain by one carbon. Mg CO 2 H + CH 3 CH 2 CH 2 -Br CH 3 CH 2 CH 2 MgBr CH 3 CH 2 CH 2 COOH n-propyl bromide butyric acid Mg CO 2 H +

4.Hydrolysis of a nitrile: H 2 O, H + R-C  N R-CO 2 H heat H 2 O, OH - R-C  N R-CO H +  R-CO 2 H heat R-X + NaCN  R-CN + H +, H 2 O, heat  RCOOH 1 o alkyl halide Adds one more carbon to the chain. R-X must be 1 o or CH 3 !

 As carboxylic acid is weak, its reactions produce the same outcomes as those learnt from the chapter of Acids, Bases and Salts  But, the reactions are less vigorous Chemical Properties of Carboxylic Acids

Pure acid Acid in water Acid Properties Weak acids (pH ≈ 3).  Most of the acid molecules are unionised in water. For example: 1.0 mol/dm 3 solution of ethanoic acid CH 3 COOH(aq)CH 3 COO  (aq) + H + (aq)

Reaction with bases  to form a salt and water For example: CH 3 COOH + NaOH CH 3 COONa + H 2 O Acid Properties

Reaction with reactive metals  to form a salt and hydrogen For example: 2CH 3 COOH + Mg (CH 3 COO) 2 Mg + H 2 Acid Properties

Reaction with carbonates  to form a salt, carbon dioxide and water For example: 2CH 3 COOH + Na 2 CO 3 2CH 3 COONa + CO 2 + H 2 O Acid Properties

carboxylic acids, reactions: 1.as acids 2.conversion into functional derivatives a)  acid chlorides b)  esters c)  amides 3.reduction 4.alpha-halogenation

as acids: a)with active metals RCO 2 H + Na  RCO 2 - Na + + H 2 (g) b)with bases RCO 2 H + NaOH  RCO 2 - Na + + H 2 O c)relative acid strength? CH 4 < NH 3 < HC  CH < ROH < HOH < H 2 CO 3 < RCO 2 H < HF

2.Conversion into functional derivatives: a)  acid chlorides

b)  esters “direct” esterification: H + RCOOH + R´OH  RCO 2 R´ + H 2 O -reversible and often does not favor the ester -use an excess of the alcohol or acid to shift equilibrium -or remove the products to shift equilibrium to completion “indirect” esterification: RCOOH + PCl 3  RCOCl + R´OH  RCO 2 R´ -convert the acid into the acid chloride first; not reversible

c)  amides “indirect” only! RCOOH + SOCl 2  RCOCl + NH 3  RCONH 2 amide Directly reacting ammonia with a carboxylic acid results in an ammonium salt: RCOOH + NH 3  RCOO - NH 4 + acid base

3.Reduction: RCO 2 H + LiAlH 4 ; then H +  RCH 2 OH 1 o alcohol Carboxylic acids resist catalytic reduction under normal conditions. RCOOH + H 2, Ni  NR

4.Alpha-halogenation: (Hell-Volhard-Zelinsky reaction) RCH 2 COOH + X 2, P  RCHCOOH + HX X α-haloacid X 2 = Cl 2, Br 2