Carboxylic Acids Acids have a sour or tart taste –Examples: Vinegaracetic acid Lemonscitric acid Tart applesmalic acid

Nomenclature Drop the e and ad oic acid If two acid groups in a molecule – keep the e and say dioic acid –Carbonyl C is always is number 1 carbon –Also called an “acyl” group Practice some on the board

Nomenclature # CCommon NameIUPAC Name 1Formic acidMethanoic acid 2Acetic acidEthanoic acid 3Propionic acidPropanoic acid 4Butyric acidButanoic acid 5Valeric acidPentanoic acid 6Caproic acidHexanoic acid

Remembering Nomenclature Formic acid…“ant acid” Acetic acid…….“acetum” (Latin=vinegar) Butyric acid……..“butter acid” Caproic acid……….“goat acid” Unbranched 3-10…….“fatty acids”

Physical Properties Highest bp of compounds studied so far! B Alcohols Alkyl halides Alkanes Increasing BP Ethers/Aldehydes/Ketones Carboxylic acids

Physical Properties Higher boil points due to hydrogen bonding and Carboxylic acid dimers –Two identical units 1 o alcohol B

Physical Properties –Foul odors butyric acidstale perspiration locker room odor, rancid butter valeric acidsmells worse (goat smell) B From Yahoo Images

Solubility of Organics One electronegative group per four carbons will make a compound dissolve in water

Fatty Acids Long un-branched carboxylic acids Most have between 12 and 20 carbons Derived from the hydrolysis of fats Most have an even number of C’s If unsaturated, the cis isomer predominates Unsaturated have lower melt points than saturated

Melting Points Saturated have higher melting points than unsaturated fatty acids

Soap Soap is made by adding NaOH to a fat This reaction is called soponification This cleaves each of the fatty acids producing the solid fatty acid salt (soap) The other product is glycerol

Soap

Soap Micelles

Modern Detergents Dodecylbenzene Sodium 4dodecylbenzenesulfonate

Acidity due to Electron Withdrawing Groups

Carboxylic Acid Reactions React as an acid with a base

Separation using soluble salts

Reduction To an Alcohol Reduction is difficult for acids, but Lithium Aluminum Hydride will do it

Fischer Esterification

Decarboxylation