Chem 102 1st Edition Lecture 13 Outline of Last Lecture I. Chapter 15: Lessons 4.1-4.4 : The Carbonyl Group, Compounds Containing Carbonyl Group, The Aldehyde and Ketone Functional Groups, Nomenclature for AldehydesOutline of Current Lecture II. 4.5 - Nomenclature for Ketones III. 4.6 - Isomerism for Aldehydes and KetonesIV. 4.7 - Selected common Aldehydes and KetonesV. 4.8 - Physical Properties of Aldehydes and KetonesCurrent Lecture4.5 Nomenclature for KetonesIUPAC Rules Rule 1: Select as the parent carbon chain the longest carbon chain that includes the carbon atom of the carbonyl group. Rule 2: Name the parent chain by changing the “-e” ending of the corresponding alkane name to “-one.” Rule 3: Number the carbon chain such that the carbonyl carbon atom receives the lowest possible number. The position of the carbonyl carbon atom is noted by placing a number immediately before the name of the parent chain. Rule 4: Determine the identity and location of any substituents, and append this information to the frontof the parent chain name. Rule 5: Cyclic ketones are named by assigning the number 1 to the carbon atom of the carbonyl group. The ring is then numbered to give the lowest number(s) to the atom(s) bearing substituents. 4.6 Isomerism for Aldehydes and Ketones• Constitutional isomers exist for aldehydes and ketones• Two types of isomers: – Skeletal isomers: arrangements of atoms in space is different. – Positional isomers: Position of the functional group is different. – Functional group isomers - Isomeric aldehyde and ketones 4.7 Selected common Aldehydes and KetonesFormaldehyde • Simplest aldehyde and has one carbon atom • It is synthesized by oxidation of methanol • Mainly used for the manufacturing of polymers • Bubbling formaldehyde through water produces formalin (formaldehyde in water with pungent smell) • Formalin is used for preserving biological specimens • In formalin formaldehyde is present in the form of HO-CH2-OH Acetone • Simplest ketone. • Colorless liquid with mild sweet odor. • Excellent solvent: it is miscible in both water and organic solvents. • Acetone is the main ingredient in gasoline treatments designed to extract water from the gas tank and allow it to pass through the engine in miscible form. • Major component of nail polish remover. • Patients with diabetes produce relatively large amounts of acetone. – Diabetic breath has mild sweet odor because of acetone. – Presence of acetone in urine consistent with diabetes. Flavorants and Odorants • Aldehydes and ketones occur widely in nature • Such compounds have higher molecular masses, pleasant odors and flavors • Often used in consumer products such as perfumes, air fresheners, etc). - Example: Butanedione• The unmistakable odor of melted butter is largely due to the four-carbon diketone - butanedione. Steroid Hormones • Important steroid hormones are ketones, – Testosterone – responsible for the development of male sex characteristics. – Progesterone – responsible for ovulation in females – Cortisone – responsible for stress and inflammation management Sunscreens and Sun-tanning Agents • Active ingredients in most commercial CH3• The compounds help absorb UV- radiation and thus prevent sunburns – Dihydroxyacetone (DHA) is a OH HO Dioxybenzone sunless” tanning agent 4.8 Physical Properties of Aldehydes and KetonesPhysical State at Room Temperature • Aldehydes: – C1-C2 aldehydes are gases – C3-C11 straight-chain aldehydes are liquids – >C11 aldehydes are solids • Ketones: – Lower molar mass ketones are colorless liquids Boiling and Melting Points • Intermediate between alcohols and alkanes • Higher boiling points than alkanes because of dipole– dipole attractions between carbonyl groups in these molecules. Solubility • Water molecules can hydrogen-bond with aldehyde and ketone molecules, which causes low-molecular-mass aldehydes and ketones to be water soluble. • Aldehydes and ketones with longer hydrocarbon chains are less soluble or insoluble in