Goals for the Day… Epoxide ring openings Aldehydes & ketones Naming Physical Properties Reactions

Water adds to epoxides with dilute acid at room temperature Product is a 1,2-diol (on adjacent C’s: vicinal) Mechanism: acid protonates oxygen and water adds to opposite side (trans addition) 18.6 Reactions of Epoxides: Ring-Opening

Anhydrous HF, HBr, HCl, or HI combines with an epoxide Gives trans product Halohydrins from Epoxides

Regiochemistry of Acid-Catalyzed Opening of Epoxides  1) Nucleophile preferably adds to less hindered site if primary and secondary C’s  2) Nucleophile adds to a tertiary carbon because of carbocation character 1) 2)

Steps of Acid-Catalyzed Opening of Epoxides 1)Protonation 2)Attack of the nucleophile from the backside Note: check for degree of substitution

Strain of the three-membered ring is relieved on ring- opening Hydroxide cleaves epoxides at elevated temperatures to give trans 1,2-diols Base-Catalyzed Epoxide Opening

Adds –CH 2 CH 2 OH to the Grignard reagent’s hydrocarbon chain Acyclic and other larger ring ethers do not react Addition of Grignards to Ethylene Oxide

Predict the products…

Answers…

Naming Aldehydes The parent chain must contain the –CHO group The –CHO carbon is numbered as C1 The suffix becomes –anal

Examples for you to try…

Answer… 4-butyl hexanal

The carbonyl carbon has to be included in the longest chain of carbons The carbonyl carbon gets priority in the numbering The suffix becomes -anone Naming Ketones Smallest possible… 2-propanone acetone 2-butanone Ethyl methyl ketone

IUPAC retains well-used but unsystematic names for a few ketones Ketones with Common Names

Examples to try

Answer 3-butyl-2-octanone

Examples to try

Answer… 7-benzyl-2-nonanone

A few times you might need to refer to the aldehyde or Ketone as an attachement… Ketones and Aldehydes as Substituents

Draw… (pick one). 3-methyl-2-pentanonePara formyl toluene

Answers…. 3-methyl-2-pentanonePara formyl toluene

Physical Properties…. Melting Point & Boiling Points -Aldehydes and ketones are “middle” range…they have dipoles -They fall below alcohols and amines, but above most other functional Groups…

Ranking m.p./b.p... ________>__________>__________>__________>__________ Highest lowest

Ranking m.p./b.p... ________>__________>__________>__________>__________ Highest lowest a e b d c

Water solubility (which will be soluble?)... Theoretically, aldehydes and ketones are soluble up to 6 carbons

The compounds containing Oxygen & Nitrogen will be soluble in water (up to 6 carbons) Note: The alkanes & alkenes are not water soluble…

Oxidize primary alcohols using pyridinium chlorochromate 19.2 Preparing Aldehydes and Ketones

Oxidize a 2° alcohol Preparing Ketones

This particular reagent gives formaldehyde and a ketone as products… Aldehydes & Ketones from Ozonolysis

Friedel–Crafts acylation of an aromatic ring with an acid chloride in the presence of AlCl 3 catalyst Recall: Aryl Ketones by Acylation

Ways to make aldehydes & ketones…

Answers…

CrO 3 in aqueous acid oxidizes aldehydes to carboxylic acids efficiently 19.3 Oxidation of Aldehydes and Ketones

Any questions?

Have a wonderful day!