1. Chapter 15 Aldehydes and Ketones
Milbank High School

2. Objectives/Study Questions
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. Objectives/Study Questions
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. Carbonyl Group Carbon atom joined to oxygen by a double bond Ketones
                                          
Carbon atom joined to oxygen by a double bond
Ketones
Aldehydes
            

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

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

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

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

9. Ketones
Carbonyl carbon gets lowest number
See examples…

10. Common Carbonyl Compounds
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. Physical Properties of Aldehydes and Ketones
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. Preparation of Aldehydes
Oxidation
Leads to carboxylic acid unless care is taken
1° alcohols
                                           
                                                                                  

13. Preparation of Ketones
Oxidation of a 2° alcohol
Utilizes chromium compounds and sulfuric acid
                                
                              

14. Chemical Properties of Aldehydes and Ketones
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. Chemical Properties of Aldehydes and Ketones
                                            
Chemical Properties of Aldehydes and Ketones
Reduction
Variety of agents can reduce aldehydes and ketones to alcohols
NaBH4 and H2 commonly used
                                                                
                                     

16. Chemical Properties of Aldehydes and Ketones
Hydration
Formaldehyde dissolves readily in water
Acetaldehyde somewhat also
Form hydrates
                                   
                                         

17. Chemical Properties of Aldehydes and Ketones
                                       
                                       
Chemical Properties of Aldehydes and Ketones
Addition of Alcohols to Carbonyl Groups
Hemiacetal
Aldehyde + alcohol
Hemiketal
Ketone + alcohol
Not very stable
Differs from
1 mol to 2 mol

18. Chemical Properties of Aldehydes and Ketones
Hemiacetals + HCl = acetal
Hemiketal + HCl = ketal