ChemBio Lab

• Common organic reactions in synthetic routes: Substitution Reactions, Oxidation, Reduction
• The goal of organic synthesis is to make compounds that have not been found naturally or cannot be obtained easily through extraction.
• Organic synthesis is the process by which complex molecules are made from simpler ones.
• Synthetic routes involve multiple steps, with each step being called a reaction.
• Substitution reactions result into one or group of atoms is replaced with another. can create Halokanes
• Oxidation refers to the loss of hydrogen or addition of oxygen. include oxidation of alcohols to aldehydes/ketones.
• Reduction involves the gain of hydrogen or the loss of oxygen
• Alkanes are not particularly useful for synthesis as they have no functional groups and all the bonds are strong. In general, they are made into more useful alkenes by thermal or catalytic cracking. Undergo free radical substitution with halogens in UV light at RT
• Designing a route

  • Draw the structure of the target molecule and the starting molecule
  • Determine if they have the same number of carbons need to put on a nitrile group by nucleophilic substitution
  • work out all the compounds that can be made from the starting molecule and all the molecules that can be made into the target molecule
  • Match the groups they have in common and work out the reagents and conditions needed
• From aldehydes

  • Include reactions oxidation to carboxylic acids
  • The conditions required are the as for oxidation of alcohols
• From Nitriles

  • Nitriles are useful as an intermediate when extending the length of the carbon chain by one carbon atom
  • The nitrile is reduced to the amine by a variety of reducing agents such as hydrogen gas in the presence of a nickel catalyst, or lithium aluminum hydride in ethoxyethane.
• Design a pathway to go from given alkene to a specific alcohol

  In which the case reagents and conditions required for the first step (alkene to haloalkane) must be given, before the second stage, reaction of the halo alkane to form the alcohol

  Step 1: Alkene-Haloalkane

  Step 2: Haloalkane- alcohol
• Common organic reactions in synthetic routes

  • Addition reactions create larger molecule often with the formation of a new single bond and a loss of double bond.
  • Elimination reactions produce smaller molecule and result in the formation of a C=C double bond
• Reaction conditions

  • Factors to consider include temperature, pressure, the use of a catalyst, and whether the reaction is carried out in an acidic or basic environment.
  • Use conditions that are safe , economical, and environmetally friendly while still achieving the desired product with high yield
• Synthetic routes

  • Pathway taken to prepare specific products
  • Series of reactions
  • How to manipulate functional groups, perform various organic reactions and control reaction conditions
  • Product target molecule with high yield and few side effects
• From Halogenoalkanes

  • Reactions usually proceed due to the dipole that exists between the carbon and halogen atoms.
  • The halide ion formed in nucleophilic substitution isa good leaving group (I.E. it is stable) driving the reaction to the side of the products
• Xantoproteic test- it test presence of aromatic amino acids or proteins containing aromatic rings.
• Indication of positive results in xantoproteic test: formation of yellow color upon the addition of concentrated nitric acid
• Principle of xantoproteic test: Nitration of aromatic rings in amino acids or proteins by concentrated nitric acid leads to the formation of yellow-colored nitro compounds, indicating the presence of amino acids
• Wagner's Test- it tests the presence of alkaloids
• Positive result in Wagner's test: Formation of brownish-red precipitate
• Principle of wagner's test: Wagner's reagent (iodine in potassium iodine) reacts with alkaloids to form insoluble iodine-alkaloid complexes, leading to the formation of the precipitate.
• Concentrated sulfuric acid test- it tests the presence of flavanoids
• formation of various color changes (Concentrated sulfuric acid test)

  typically ranging from yellow to orange to red, depending on the specific flavanoid present.
• Flavanoids contain phenolic structures that can undergo dehydration and oxidation reactions when treated with concentrated sulfuric acid. the color produced can vary depends on what flavanoids present
• Gelatin Test

  Presence of tannins
• indication of positive result in gelatin test

  formation of white precipitate
• Tannins can form insoluble complexes with proteins, such as gelatin, resulting in the formation of precipitate
• Sodium hydroxide test


  presence of flavonoids
• Positive result in Sodium hydroxide test

  yellow coloration
• Flavanoids react with sodium hydroxide to produce yellow coloration due to the presence of conjugated double bonds in their structure
• Salwoski Test

  Presence of terpenoids or steroids
• positive result in salkowski test

  development of reddish-brown coloratiom
• The reaction involves the formation of a complex between the terpenoids/steroids and sulfuric acid, leading to the development of the characteristic color.
• Keller-killiani Test

  Presence of glycosides, particularly cardiac glycosides
• Positive result in Keller-killiani Test

  Formation of red color
• The reagent, which contains glacial acetic acid and concentrated sulfuric acid, reacts with cardiac glycosides to produce a red color due to the presence of sugar moieties in the glycoside molecule
• Frothing Test

  Presence of saponins
• positive result in Frothing Test

  Formation of froth upon shaking
• Saponins can form stable foam when shaken vigorously due to their amphiphilic nature, which allows them to interact with water and trap air bubbles.