Chapter 16,17 & 18 Amines, Aldehydes, Ketones and Carboxylic Acids

1. Chemistry B11 Chapter 16,17 & 18 Amines, Aldehydes, Ketones and Carboxylic Acids

2. Amines

3. Amines • Amines: • Are derivatives of ammonia NH3. • Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine). • CH3-NH2CH3-NH-CH3 -NH2 amino group NH2

4. Amines Amines are classified into three groups: depending on the number of carbon groups bonded to nitrogen. CH3 CH3   CH3—NH2 CH3—NH CH3—N—CH3 Tertiary 3° Secondary 2° Primary 1°

5. NH2 NH2 CH3-CH-CH3 CH3-CH-CH-CH3 Cl Naming Amines IUPAC name – 1° amines • The same method as we did for alcohols. • - Drop the final “-e” of the parent alkane and replace it by “-amine”. • - Use a number to locate the amino group (-NH2) on the parent chain. 3 1 5 3 2 4 6 1 2 4 3 1 2 2-propanamine 3-chloro-2-butanamine 1,6-hexanediamine

6. Naming Amines Common name Names of alkyl groups (In alphabetical order) + “amine” CH3—CH2—NH2 ethylamine CH3—NH —CH3 dimethylamine CH3 | CH3—N—CH2—CH3 ethyldimethylamine

7. Aniline (common name) NH2 Aniline NH2 NH2 NH2 2 2 1 1 2 1 CH3 3 3 3 4 CH3 4 Cl NO2 3-Methylaniline 4-Nitroaniline 4-Chloro-3-methylaniline

8. CH3 CH3-N-CH2-CH3 aniline Naming Amines IUPAC name – 2° and 3° amines • Take the largest group bonded to nitrogen as the parent amine. • Name the smaller group(s) bonded to nitrogen, and show their locations on nitrogen by using the prefix “N”. N,N-Dimethylethanamine

9. N CH3 H H Heterocyclic amines When N is one of the atoms of a ring. Pyrrolidine Pyridine Nicotine

10. Physical properties of Amines • They have unpleasant odors (rotting fish like ammonia). • They are polar compounds. • Difference in electronegativity between N - H (3.0 – 2.1 = 0.9) • 3. 1° and 2° amines have hydrogen bonds (N-H). • Weaker than alcohols (O-H). • 3° amines do not form hydrogen bonds (no H atom). • Boiling points: Hydrocarbons< Amines < Alcohols • Almost soluble in water (hydrogen bonding).

11. H H . . . . - . . . . + . . . . CH3 + CH3 N N H H – O – H O – H H H Chemical properties of Amines They are weak bases (like ammonia): react with acids. (to form water-soluble salts) Some amines present in our blood and make it approximately basic (pH = 7.4).

12. Chemical properties of Amines Aliphatic amines are weak bases by comparison with inorganic bases such as NaOH, they are strong bases among organic compounds. Aliphatic amines are stronger bases than aromatic amines. (slightly stronger than NH3)

13. Examples • Complete each acid-base reaction and name the salt formed.

14. Examples • Complete each acid-base reaction and name the salt formed. Solutions:

15. Aldehydes Ketones

16. O = C Carbonyl group Aldehydes Ketones Carboxylic acids Esters

17. Aldehydes and Ketones O = C • In an aldehyde, at least one H atom is attached to a carbonyl group. • In a ketone, two carbon groups are attached to a carbonyl group.

18. Naming Aldehydes Step 1 Select the longest carbon chain that contains the carbonyl group (C=O). Step 2 Number from the end nearest C=O group. Step 3 Change the ending of parent alkane from -e to -al. No number for carbonyl group C=O (it always comes first). Step 4 Give the location and name of each substituent (alphabetical order) as a prefix to the name of the main chain.

19. Naming Aldehydes • Common names for the first two aldehydes use the prefixes “form” (1C) and “acet” (2C)followed by “aldehyde”. • OOO • ║ ║ ║ • H─C─H CH3─ C ─H CH3─CH2─ C ─H • methanal ethanal propanal • (formaldehyde) (acetaldehyde)

20. O • ║ • CH3─CH─CH2─ C─H 3-Methylbutanal • O • ║ • Cl─CH2─CH2─ C─H 3-chloropropanal CH3 4 3 2 1 3 2 1

21. Naming Ketones Step 1 Select the longest carbon chain that contains the carbonyl group (C=O). Step 2 Number from the end nearest C=O group. Step 3 Change the ending of parent alkane from -e to -one. Use the number to show the location of C=O. Step 4 Give the location and name of each substituent (alphabetical order) as a prefix to the name of the main chain.

22. Naming Ketones • In the common name, name the “alkyl groups” alphabetically attached to the carbonyl group and add the word “ketone”. • OO • ║ ║ • CH3 ─ C ─CH3 CH3─C─CH2─CH3 • propanone 2-butanone • (dimethyl ketone) (ethyl methyl ketone) 2 1 3 4

23. 3-Chloro Cl

25. δ- δ+ δ- δ+ Physical properties of Aldehydes and Ketones • They have strong odors (ketones have pleasant odors). • They are polar compounds. • Only dipole-dipole interactions (no hydrogen bonding). • Low boiling points compare to amines and alcohols. • Soluble in water (no soluble in nonpolar compounds). C-O 3.5-2.5 = 1 Higher than hydrocarbons. H O δ+ H Hydrogen bond with water.

26. O = CH3─CH2─CH2─CH2─C─H Pentanal Liquid aldehydes are sensetive to oxidation. No oxidizing agent Chemical properties of Aldehydes and Ketones 1. Oxidation: only for aldehydes (not for ketones). O K2Cr2O7 = CH3─CH2─CH2─CH2─C─OH H2SO4 Pentanoic acid K2Cr2O7: Oxidizing agent

27. t r a n s i t i o n m e t a l c a t a l y s t H 2 1 - P e n t a n o l t r a n s i t i o n O OH m e t a l c a t a l y s t = - H + CH3─CH─CH2─CH3 CH3─C─CH2─CH3 2 2-butanol 2-butanone Chemical properties of Aldehydes and Ketones 2. Reduction: • Like reducing the alkene (C = C) to alkane (C – C): • Reduction of an aldehyde gives a primary alcohol (-CH2OH). • Reduction of a ketone gives a secondary alcohol (-CHOH-). O = + CH3─CH2─CH2─CH2─C─ H CH3─CH2─CH2─CH2─CH2─ OH Pentanal

28. Chemical properties of Aldehydes and Ketones NaBH4 Sodium borohydride: produces hydride ion: H- Reducing agent Reduction mechanism: -

29. Carboxylic Acids

30. Carboxylic Acids A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a hydroxyl group. carbonyl group O  CH3 —C—OHhydroxyl group or CH3COOH carboxyl group CH3CO2H

31. Naming Carboxylic Acids • In the IUPAC name of carboxylic acids, the “-e” in the name of the longest chain is replaced by “-oic acid”. • The common names use prefixes “form-” and “acet-” for the first two carboxylic acids. • H-COOH methanoic acid formic acid • CH3-COOH ethanoic acid acetic acid • CH3-CH2-COOH propanoic acid • CH3-CH2-CH2-COOH butanoic acid

32. O H H N C O O H 2 O H Naming Carboxylic Acids • Number the chain beginning with the carbon of the carboxyl group. • Because the carboxyl carbon is understood to be carbon 1, there is no need to give it a number. CH3 CH2 – CH3 1 3 1 2 CH3─CH─CH2─COOH CH3─CH2─CH─COOH 2-Ethylbutanoic acid 3-Methylbutanoic acid O 4 1 5 1 5-Hydroxylhexanoic acid 4-Aminobenzoic acid

33. H O O H H O O H H O H O H O O H O H O H Naming Dicarboxylic Acids • Add the suffix “-dioic acid” to the name of the parent alkane that contains both carboxyl groups; thus, “-ane”becomes “-anedioic acid”. • The numbers of the carboxyl carbons are not indicated because they can be only at the ends of the chain. O O O 1 3 1 2 O Ehanedioic acid Propanedioic acid O O O O 5 1 1 1 6 4 O O Butanedioic acid Pentanedioic acid Hexanedioic acid

34. Hydrogen bonding between two molecules d - d + O H O C C H H C C 3 3 O O H d + d - Physical properties of Carboxylic Acids • 1- The carboxyl group contains three polar covalent bonds; • C=O, C-O, and O-H. So they are so polar. • 2-Carboxylic acids have higher boiling points than other types of organic compounds (with the same molecular weight) because of hydrogen bonding. • 3- They are more soluble in water than alcohols, ethers, aldehydes, and ketones because of stronger hydrogen bonding. • 4- Liquid carboxylic acids have sharp and disagreeable odors. • 5- They taste sour (exist in pickle, lime, and lemon).

35. Fatty Acids • Long, unbranched chain carboxylic acids and they are found in animal fats, vegetable oils, or phospholipids of biological membranes. • Most have between 12 and 20 carbons in an unbranched chain. • In most unsaturated fatty acids, the cis isomer is usually existed and the trans isomer is rare. • Unsaturated fatty acids have lower melting points than their saturated counterparts. Cis

36. Fatty Acids Saturated fatty acids are solids at room temperature. Packed together  Maximum London dispersion forces

37. Fatty Acids Unsaturated fatty acids are liquids at room temperature. Can not packed together  London dispersion forces Cis

38. Esters In an ester, the H in the carboxyl group is replaced by an alkyl group. O  CH3 —C—O —CH3 ester group

39. Soaps • Natural soaps are sodium or potassium salts of fatty acids. • They are prepared from a blend of tallow and coconut oils (triglycerides). • Triglycerides are triesters of glycerol. • the solid fats are melted with steam and the water insoluble triglyceride layer that forms on the top is removed. CH2 – CH – CH2 OH OH OH 1,2,3-Propanetriol (glycerol, glycerin)

40. Soaps • Preparation of soaps begins by boiling the triglycerides with NaOH. The reaction that takes place is called saponification. • Boiling with KOH gives a potassium soap.

41. Soaps Hydrophobic part: nonpolar Hydrophilic part: polar (remains in contact with environment)

42. Soaps When soap is mixed with dirt (grease, oil, and …), soap micelles “dissolve” these nonpolar, water-insoluble molecules.

43. Chemical properties of Carboxylic Acids 1- They are weak acids. Substituents of high electronegativity, especially -OH, -Cl, and -NH3+, near the carboxyl group increase the acidity of carboxylic acids. 2- Reaction with bases: They react with NaOH, KOH, NH3, and other strong bases to form water-soluble salts.

44. Chemical properties of Carboxylic Acids 3- Fischer Esterification: - A carboxylic acid reacts with an alcohols to form an ester. - Using an acid catalyst such as concentrated sulfuric acid. The best way to prepare an ester.