M6 M7

• Carbonyl Group


  • General Formula of an Aldehyde - R(C=O)H
  • General Formula of a Ketone - R)C=O)R

  
• Carbonyl Group


  • Responsible for the chemical and physical properties of Aldehyde and Ketone
  • Highly polarized group because of the greater electronegativity of the oxygen atom
  • Electron density of oxygen is increased
  • Electron density of carbon is decreased
  • Susceptible to nucleophilic attack
• Nucleophilic attack on carbonyl group

  1. Polarization

  2. Nucleophile can approach the carbonyl carbon either above or below the plane of the pi bond
• Oxidation of Alcohols


  • Oxidation of Primary Alcohols - yields aldehydes
  • Oxidation of Secondary Alcohols - yields ketones
• 2,4-dinitrophenylhydrazine


  • Reacts with aldehydes and ketones to form red-orange precipitate of 2,4-dinitrophenylhydrazone
  • Used to differentiate carbonyl compounds from other classes of organic compounds

  
• Ketone-sodium bisulfite reaction


  • Ketones will form a water-soluble crystalline bisulfite addition product with sodium bisulfite
  • Aldehydes and methyl groups larger than methyl will not react because of overcrowding and steric inhibition to the approach of an attacking species
• Aldehyde


  • Organic compounds containing the carbonyl (formyl) functional group
  • Carbonyl carbon is attached to a hydrogen atom and an R group (alkyl or aryl)
  • Formed by replacing the hydrogen atom of a hydrocarbon by the formyl group
  • Flavors of Almond, vanilla beans, and cinnamon are due to the presence of aldehydes
• 2,4-Dinitrophenylhydrazine Test for Aldehydes


  1. Take a small quantity of organic compound, add rectified spirit, shake, and add 2,4-dinitrophenyl hydrazine solution

  2. Forms a yellow or orange precipitate of 2,4-dinitrophenyl hydrazone

  
• Sodium bisulfite Test for Aldehydes

  1. Take a small quantity of sodium bisulfite (saturated) in a boiling tube, add a small quantity of organic compound, cork the test tube, shake, and leave it for some time

  2. Aldehyde gives an addition product with sodium bisulfite - white crystalline in nature
• Schiff's Test for Aldehydes


  1. Take a small quantity of organic compound, add a small amount of Schiff's reagent

  2. Schiff's Reagent gives a characteristic pink or magenta color with aldehyde

  
• Tollen's Test to distinguish between aldehydes and ketones

  1. Take a small quantity of silver nitrate solution, add a few drops of dilute sodium hydroxide, add excess of dilute ammonium hydroxide and shake, add a small quantity of organic compound, heat in a boiling water bath

  2. Aldehyde reduces silver ions in the test reagent to elemental silver which is accumulated on the inner surface of the test tube - silver mirror
• Fehling's Test


  1. Take a small quantity of organic compound, add a small amount of Fehling's solution A, add a small quantity of Fehling's Solution B, heat

  2. Aldehyde reduces Copper (II) ions present in the test reagent to red precipitate of copper (I) oxide
• Tollen's Reagent


  • Aqueous diamminesilver solution
  • Should be freshly prepared and acidified immediately after use to prevent the formation of explosive silver nitride
• Ketone


  • Organic compounds containing the ketonic functional group
  • Carbonyl carbon is attached to two R groups (alkyl or aryl)
  • Flavors of Berries and Mushrooms are due to the presence of ketones

  
• 2,4-dinitrophenylhydrazine Test for Ketones


  1. Take a small quantity of organic compound, add a small amount of rectified spirit, shake, and add a small quantity of 2,4-dinitrophenylhydrazine solution

  2. 2,4-dinitrophenylhydrazine reacts with the carbonyl group present in ketone to form a yellow or orange precipitate of 2,4-dinitrophenyl hydrazone

  
• Sodium bisulfite Test for Ketones

  1. Take a small quantity of saturated solution of sodium bisulfate in a boiling tube, add a small quantity of organic compound, cork the test tube, shake, and leave it for some time

  2. Ketone gives an addition product with sodium bisulfite - white crystalline in nature
• Meta-dinitrobenzene Test for Ketones

  1. Take a small quantity of organic compound, add a small quantity of meta-dinitrobenzene, add a small amount of dilute sodium hydroxide solution, shake

  2. Ketones give a violet coloration that slowly fades away
• Sodium nitroprusside Test for Ketones

  1. Take a few crystals of sodium nitroprusside, add a small amount of distilled water, shake, add a small quantity of organic compound, add a small quantity of dilute sodium hydroxide solution

  2. Anion of Ketone reacts with nitroprusside ions to form a red colored complex
• Iodoform Test


  • To check the presence of carbonyl compound
  • Gives a pale yellow color precipitate and antiseptic odor
  • Insoluble yellow crystal/precipitate
• Carbohydrates


  • Large biological molecules consisting of carbon, hydrogen, and oxygen
  • General Formula - Cm(H2O)n
  • One of the important nutrients present in our food
  • Photosynthesis - carbohydrates are produced from carbon dioxide and water in the presence of chlorophyll and sunlight
  • Commonly known carbohydrates - Glucose, Lactose, Sucrose, and Starch
  • Uses - Main source of energy, help fuel your brain, help your kidney, heart muscles, and central nervous system
• Solubility Test for Carbohydrates

  1. Take a small amount of glucose, lactose, sucrose, and starch in four test tubes, add a small volume of distilled water, shake

  2. Soluble - glucose, lactose, and sucrose

  3. Insoluble - starch
• Molisch's Test for Carbohydrates

  1. Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes, add a few drops of Molisch's Reagent, add a small amount of concentrated sulfuric acid slowly along the side of the test tube

  2. Concentrated Sulfuric Acid dehydrates carbohydrates to form furfuraldehyde or its derivative which further reacts with a-naphthol present in the Molisch's Reagent to form a colored product that appears as a purple ring at the interface between the acid and test layer
• Fehling's Test for Carbohydrates

  Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes, add a small amount of Fehling's solution A, add a small quantity of Fehling's Solution B, heat
• Solubility Test


  1. Take a small amount of glucose, lactose, sucrose, and starch in four test tubes

  2. Add a small volume of distilled water

  3. Shake

  4. Soluble - glucose, lactose, and sucrose

  5. Insoluble - starch
• Molisch's Test


  • For the presence of carbohydrates
  • General test for carbohydrates
• Molisch's Test Procedure


  1. Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes

  2. Add a few drops of Molisch's Reagent

  3. Add a small amount of concentrated sulfuric acid slowly along the side of the test tube
• Concentrated Sulfuric Acid


  Dehydrates carbohydrates to form furfuraldehyde or its derivative which further reacts with a-naphthol present in the Molisch's Reagent
• Molisch's Test Result


  Forms a colored product that appears as a purple ring at the interface between the acid and test layer
• Fehling's Test Procedure


  1. Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes

  2. Add a small quantity of Fehling's solution A and B

  3. Heat in a boiling water bath
• Reducing Sugars


  Glucose and lactose reduce the copper (II) ions in the test reagent, forming a red precipitate of cuprous oxide
• Non-reducing Sugars


  Sucrose and starch do not form such a precipitate
• Benedict's Test


  • Used in place of Fehling's solution
  • Benedict's Reagent is aqua blue
  • Positive Result is a blue to brick red precipitate
• Benedict's Test Procedure


  1. Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes

  2. Add a small quantity of Benedict's reagent

  3. Heat in a boiling water bath
• Tollen's Test


  • Reducing Sugars - glucose and lactose reduce silver ions in the test reagent to elemental silver, appearing as a silver mirror on the inner surface of the vessel
  • Non-reducing Sugars - sucrose and starch do not form such a silver mirror
• Tollen's Test Procedure


  1. Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes

  2. Add a small quantity of Tollen's Reagent

  3. Heat in a boiling water bath
• Iodine Test Procedure


  1. Take a small quantity of aqueous solution of glucose, lactose, sucrose, and suspension of starch in four test tubes

  2. Add a few drops of iodine solution
• Iodine Test


  • Iodine reacts with starch to form a blue colored starch/iodine complex
  • Glucose, Lactose, and Sucrose do not form such a color
• Fiber


  • Aids in digestion
  • Keeps blood cholesterol level in check
• Two Main Forms of Carbohydrates

  • Sugar - fructose, glucose, lactose
  • Starch
• Major Functions of Carbohydrates

  • Provide energy and regulation of blood glucose
  • Glucose is the only sugar in our brain
  • Spare the use of protein for energy
  • Break down fatty acid and preventing ketosis
  • Biological recognition process
  • Flavor and sweetener
  • Dietary fiber