*

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

*

*

1)

*

*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))

*

*

test for methyl ketones Yellow ppt

*

Then + H+ alcohol

*

*

*

*

* melting points of derivatives

* ketones bp semi- 2,4-dinitro- oxime

* carbazone phenylhydrazone

* 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

*

*

*

Crossed Cannizzaro:

*

*

*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.”