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

Amines

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

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 Primary 1° Secondary 2° Tertiary 3°

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. CH3-CH-CH3 NH2 CH3-CH-CH-CH3 NH2 Cl 3 5 3 1 6 4 2 1 3 2 2 1 4 2-propanamine 3-chloro-2-butanamine 1,6-hexanediamine

Names of alkyl groups (In alphabetical order) + “amine” 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

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

Naming Amines IUPAC name – 2° and 3° amines aniline CH3 CH3-N-CH2-CH3 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”. aniline CH3-N-CH2-CH3 CH3 N,N-Dimethylethanamine

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

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).

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

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)

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

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

Aldehydes Ketones

Carbonyl group C = O Aldehydes Ketones Carboxylic acids Esters

= 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.

No number for carbonyl group C=O (it always comes first). 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.

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

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

Naming Ketones Step 1 Step 2 Step 3 Step 4 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.

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

3-Chloro Cl

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). δ+ δ- C-O 3.5-2.5 = 1 Higher than hydrocarbons. H δ+ O H δ+ δ- Hydrogen bond with water.

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

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 t r a n s i o m e l c y = CH3─CH2─CH2─CH2─C─ H + H 2 CH3─CH2─CH2─CH2─CH2─ OH Pentanal 1 - P e n t a o l H 2 t r a n s i o m e l c y + CH3─C─CH2─CH3 = O CH3─CH─CH2─CH3 - OH 2-butanol 2-butanone

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

Carboxylic Acids

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

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

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 3 1 2 1 CH3─CH─CH2─COOH CH3─CH2─CH─COOH 3-Methylbutanoic acid 2-Ethylbutanoic acid O H O 4 1 5 H 2 N C O H 1 O H 5-Hydroxylhexanoic acid 4-Aminobenzoic acid

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 H O 1 3 1 2 O H H O O H O Ehanedioic acid Propanedioic acid O O O O H O 1 5 1 H O 1 4 6 O H H O O H O H O O Butanedioic acid Pentanedioic acid Hexanedioic acid

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). H 3 C O d - + Hydrogen bonding between two molecules

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

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

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

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

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)

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.

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

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

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.

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.