Chemistry for Health Sciences II Lecture 20 Term 3 2024 PDF

Chemistry for Health Sciences II Two credits Term 3, 2024 King Saud bin Abdulaziz University for Health Sciences (Lecture 20) Objectives: At the end of this lecture, students should be able to: Write IUPAC and common names for amines. Identify primary, secondary, or tertiary amines or quaternary amm...

Chemistry for Health Sciences II Two credits Term 3, 2024 King Saud bin Abdulaziz University for Health Sciences (Lecture 20) Objectives: At the end of this lecture, students should be able to: Write IUPAC and common names for amines. Identify primary, secondary, or tertiary amines or quaternary ammonium salts. Write a chemical equation for the reaction of amines with acid or water. Write a chemical equation to describe the reaction of primary amines with aldehyde or ketone to form Imine (Schiff base). Identify the different functional groups found in drug molecules (serves as summary for all functional groups). Amines Amines are derivatives of ammonia Most important type of organic base found in nature Consider as if substituted ammonia: – R can be either aliphatic or aromatic Comparison of NH3 to Amines Amines have a trigonal pyramidal structure Classification of Amines Physical Properties Amines form hydrogen bonds but not as strongly as alcohols – Nitrogen is less electronegative than oxygen Tertiary amines cannot hydrogen bond to each other Amine Boiling Points Amines have boiling points between alkanes and alcohols Tertiary amines boil lower than 1o or 2o of similar MW Boiling Point Example Which molecule in each pair will have the higher boiling point? Methanol or Methylamine Dimethylamine or Water Methylamine or Ethylamine Propylamine or Butane Solubility All amines can form hydrogen bonds with water Amines up to 6 carbons long are water soluble due to this hydrogen bonding Water solubility decreases as the length of the hydrocarbon portion of the molecule increases Nomenclature of Amines Amines can be named in different ways: a) Primary amines are named as alkanamine as follow: 1. Find the parent compound - Longest continuous carbon chain containing the amine group 2. Dropping the final –e of the parent name and adding the suffix –amine 3. Number the parent chain to give the amine carbon the lowest possible number 4. Name and number all substituents as usual Nomenclature of Amines b) Common name of amines Name the alkyl groups attached to the N in alphabetical order Add –amine The name is continuous, no spaces between groups Nomenclature of Amines C) In the IUPAC system, the amino group, -NH2, is named as a substituent, as in the following examples: Organic Chem. Hart-Chap. 11 12 Amino groups as substituents Amino groups rank below OH groups and higher oxidation states of carbon, in such cases name the amino group as a substituent. 13 Aromatic & Heterocyclic Amines Heterocyclic amines are: – Cyclic compounds – Have at least one N in the ring – MANY are physiologically active and many are critical in biochemistry Medically Important Amines: Decongestants and Sulfa Drugs Decongestants shrink the membranes lining the nasal passages Sulfa drugs (first chemicals used to fight infections) are also made from amines General Knowledge Amines as Bases Amines are weak bases They accept H+ when dissolved in water – Lone pair electrons of nitrogen can be shared with a proton from water – An alkylammonium ion is produced – Hydroxide ions are also formed, making solutions basic Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display An Example of an Amine in Water Example of the basicity of amines: Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display Neutralization Reaction Amines form salts by accepting a proton from strong mineral acids Alkylammonium Salts Name amine salts by replacing the suffix – amine with ammonium Add the name of the anion Converting amines to salts often makes insoluble amines soluble as the salts are ionic Preparation of Amines 1) Reduction of nitro compounds: Aromatic nitro compounds, i.e. NH2 N O2 3 H 2, N i or 1 ) S n C l2 , H C l 2 ) N a O H , H 2O + 2 H 2O Preparation of Amines 2) Reduction of amides: O 1 ) L iA lH 4 , e th e r N H2 2 ) H 3O + Works for 2° and 3 amides as well. N H2 Preparation of Amines 3) Reduction of nitriles: 1 ) L iA lH 4 , e t h e r N 2 ) H 3O N H2 + or N H 2, N i N H2 Reactions: Addition of Amines  Amines react with the carbonyl group of aldehydes and ketones in the presence of an acid catalyst to give products that contain a carbon– nitrogen double bond: H2N O CH3 C H + H N CH3 C + H2O H an Imine (a Schiff base) Summary of Functional Groups Summary of Functional Groups Name the functional group in each of the following molecules. NH2 O O What are the functional groups found in Cthese + C CH3 O molecules? HO CH3 acetic anhydride p-hydroxyaniline O NHCCH3 HO acetaminophen (TYLENOL®) Artificial Sweetener Atorvastatin (Lipitor)