Aldehydes.pptxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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1. aldehydes PrESENTED BY: GROUP 2

2. INTRODUCTION • Aldehydes contains carbonyl functional group. • A carbonyl group is a carbon atom double-bonded to an oxygen atom . ( C=O ) • The structural representation for a carbonyl group is:

3. • An Aldehyde is a carbonyl-containing organic compound in which the carbonyl carbon atom has at least one hydrogen atom directly attached to it . • An aldehyde functional group can be bonded to only one carbon atom because three of the four bonds from an aldehyde carbonyl carbon must go to oxygen and hydrogen. • The remaining group attached to the carbonyl carbon atom can be hydrogen, alkyl group, or a cycloalkyl group.

4. • Linear notations of aldehydes : -CHO and –RCHO • In an aldehyde, note that the carbonyl group is always located at the end of a hydrocarbon chain.

5. Where does the term ‘’aldehyde’’ came from? • The term Aldehyde stems from alcohol dehydrogenation , indicating that aldehydes are related to alcohols by the loss of hydrogen. • Aldehydes are related to alcohol in some manner that alkanes are related to alkenes. • In a like manner, removal of a hydrogen atom from the –OH group of an alcohol and from the carbon atom to which the hydroxyl group is attached produces a carbonyl group.

6. Physical properties of aldehydes • 1 – 2 carbons – gases at room temperature • 3 – 11 carbons – straight chain saturated aldehydes are liquids • Aldehydes have higher boiling points than alkanes because of dipole-dipole interactions possible. • Aldehydes have lower boiling points than the corresponding alcohols because no hydrogen bonding occurs as it does with alcohols.

7. Solubility of aldehydes • Aldehydes with one to four carbons are soluble in water. • Aldehydes with five or more carbons are not very soluble in water .

8. • Low molecular mass aldehyde have pungent, penetrating, unpleasant odors . • Higher molecular mass aldehydes (above C 8 ) are more fragrant.

9. Quiz in sci 105 – organic chemistry aldehydes Name: Course & Year: Date: Score: Multiple Choice Direction. Read the questions carefully. Write the letter of the correct answer on your answer sheet. 1. An aldehydes has a higher boiling points than an alcohol. True b. False 2. Which of the following aldehydes would be NOT very soluble in water? a. Propanal b. Hexanal c. Ethanal d. Butanal 3. It is the linear notation of aldehydes. a. RCOH b. RCHO c. OCRH d. RHCO 4. Higher molecular mass have _____ odor . a. Pleasant b. unpleasant c. pungent d. penetrating 5. Aldehydes react with alcohols to form hemiacetals and acetals . a. True b. False

10. Identification. Direction. Indicate whether each of the following compounds is a hemiacetals or acetals . 6. 7. Direction. Assign IUPAC names to the following aldehydes. 8. 9. 10.