Aldehyde and Ketones with *Featured reactions

Transcription

1 * Aldehyde and Ketones with *Featured reactions

2 *1.What is the general structure for an aldehyde? A ketone? *2.How are the common names of aldehydes and ketones determined? How are aldehydes and ketones named using IUPAC nomenclature? *3.Why are the boiling points of aldehydes and ketones higher than those of ethers and alkanes of similar molar masses, but lower than those of comparable alcohols? *

3 *4.How do the solubilities of aldehydes and ketones of four carbons or less compare to the solubilities of comparable alkanes and alcohols in water? *5.How are aldehydes and ketones prepared? *6.What typical reactions take place with aldehydes and ketones? *7.What are some common aldehydes and ketones and their uses? *

4 *Carbon atom joined to oxygen by a double bond *Ketones *Aldehydes *

5 Comes from alcohol dehydrogenation Obtained by removing of a hydrogen from an alcohol *

6 * *Both common and IUPAC names frequently used *Common names from acids from which aldehydes can be converted

7 *IUPAC *Longest chain with aldehyde *Drop e and add -al *Aldehyde takes precedence over all other groups so far *Examples *

8 * *Naming: *Drop e, add -one *Many common names *Simplest is 3 carbons *C. name: acetone *IUPAC: propanone

9 *Carbonyl carbon gets lowest number *See examples *

10 * * Formaldehyde * Manufactured from methanol * Used in many polymers * Acetaldehyde * Prepared from ethyl alcohol * Formed in the detoxification of alcohol in the liver * Acetone * Formed in the human body as a by-product of lipid metabolism * Excreted in the urine * Hormones * Steroid hormones * Progesterone/Testosterone

11 *Carbon-oxygen double bond is very polar *Affects boiling points *More than ethers (C-O bonds) *Less than alcohols (C-OH bonds) *Odors *Low aldehydes very pungent *High aldehydes pleasant odors (perfumes) *Solubility *Similar to alcohols * and ethers *Soluble up to about 4 carbons *Insoluble after that

12 * *Oxidation *Leads to carboxylic acid unless care is taken *1 alcohols

13 *Oxidation of a 2 alcohol *Utilizes chromium compounds and sulfuric acid *

14 *Both under-go combustion reactions *Oxidation *Aldehydes can be oxidized, ketones can t *See Pg 403 *Tollen s reagent *Benedict s reagent *Fehling s reagent *

15 *Reduction *Variety of agents can reduce aldehydes and ketones to alcohols *NaBH4 and H2 commonly used *

16 *Hydration *Formaldehyde dissolves readily in water *Acetaldehyde somewhat also *Form hydrates *

17 * *Addition of Alcohols to Carbonyl Groups *Hemiacetal *Aldehyde + alcohol *Hemiketal *Ketone + alcohol *Not very stable *Differs from *1 mol to 2 mol

18 *Hemiacetals + HCl = acetal *Hemiketal + HCl = ketal *

19 *oxidation * reduction * nucleophilic addition *Aldehydes are easily oxidized, ketones are not. *Aldehydes are more reactive in nucleophilic additions than ketones. *

20 *Reactions of aldehydes and ketones: * oxidation * reduction * nucleophilic addition *Aldehydes are easily oxidized, ketones are not. *Aldehydes are more reactive in nucleophilic additions than ketones. *

21 reduction reduction oxidation nucleophilic addition

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25 * Aldehydes & ketones, reactions: * Oxidation * Reduction * Addition of cyanide * Addition of derivatives of ammonia * Addition of alcohols * Cannizzaro reaction * Addition of Grignard reagents * (Alpha-halogenation of ketones) * (Addition of carbanions)

26 * 1) Oxidation * Aldehydes (very easily oxidized!) * CH3CH2CH2CH=O + KMnO4, etc. CH3CH2CH2COOH * carboxylic acid * CH3CH2CH2CH=O + Ag+ CH3CH2CH2COO- + Ag * Silver mirror * Tollen s test for easily oxidized compounds like aldehydes. * (AgNO3, NH4OH(aq))

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28 * test for methyl ketones Yellow ppt

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33 Then + H+ alcohol

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42 * melting points of derivatives * ketones oxime bp semi- 2,4-dinitro- * phenylhydrazone carbazone * 2-nonanone * acetophenone * menthone * 2-methylacetophenone * 1-phenyl-2-propanone * propiophenone * 3-methylacetophenone * isobutyrophenone

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48 * Crossed Cannizzaro:

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53 * Aldehydes & ketones, reactions: * Oxidation * Reduction * Addition of cyanide * Addition of derivatives of ammonia * Addition of alcohols * Cannizzaro reaction * Addition of Grignard reagents * (Alpha-halogenation of ketones) * (Addition of carbanions)

54 *Planning a Grignard synthesis of an alcohol: *The alcohol carbon comes from the carbonyl compound. *The new carbon-carbon bond is to the alcohol carbon. New carbon-carbon bond

55 *Planning a Grignard synthesis of an alcohol: *The alcohol carbon comes from the carbonyl compound. *The new carbon-carbon bond is to the alcohol carbon. New carbon-carbon bond

56 * The Grignard Song (sung to the tune of America the Beautiful ) * Harry Wasserman * The carbonyl is polarized, * the carbon end is plus. * A nucleophile will thus attack * the carbon nucleus. * The Grignard yields an alcohol * of types there are but three. * It makes a bond that corresponds * from C to shining C.

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