* Aldehyde and Ketones with *Featured reactions
*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? *
*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? *
*Carbon atom joined to oxygen by a double bond *Ketones *Aldehydes *
Comes from alcohol dehydrogenation Obtained by removing of a hydrogen from an alcohol *
* *Both common and IUPAC names frequently used *Common names from acids from which aldehydes can be converted
*IUPAC *Longest chain with aldehyde *Drop e and add -al *Aldehyde takes precedence over all other groups so far *Examples *
* *Naming: *Drop e, add -one *Many common names *Simplest is 3 carbons *C. name: acetone *IUPAC: propanone
*Carbonyl carbon gets lowest number *See examples *
* * 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
*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
* *Oxidation *Leads to carboxylic acid unless care is taken *1 alcohols
*Oxidation of a 2 alcohol *Utilizes chromium compounds and sulfuric acid *
*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 *
*Reduction *Variety of agents can reduce aldehydes and ketones to alcohols *NaBH4 and H2 commonly used *
*Hydration *Formaldehyde dissolves readily in water *Acetaldehyde somewhat also *Form hydrates *
* *Addition of Alcohols to Carbonyl Groups *Hemiacetal *Aldehyde + alcohol *Hemiketal *Ketone + alcohol *Not very stable *Differs from *1 mol to 2 mol
*Hemiacetals + HCl = acetal *Hemiketal + HCl = ketal *
*oxidation * reduction * nucleophilic addition *Aldehydes are easily oxidized, ketones are not. *Aldehydes are more reactive in nucleophilic additions than ketones. *
*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. *
reduction reduction oxidation nucleophilic addition
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* 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)
* 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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* test for methyl ketones Yellow ppt
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Then + H+ alcohol
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* melting points of derivatives * ketones oxime bp semi- 2,4-dinitro- * phenylhydrazone carbazone * 2-nonanone 195 119 56 * acetophenone 202 199 240 60 * menthone 209 189 146 59 * 2-methylacetophenone 214 205 159 61 * 1-phenyl-2-propanone 216 200 156 70 * propiophenone 220 174 191 54 * 3-methylacetophenone 220 198 207 55 * isobutyrophenone 222 181 163 94
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* Crossed Cannizzaro:
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* 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)
*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
*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
* 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.