Org semi

• Tollens' test


  1. Tollens' reagent (silver nitrate and ammonia) oxidizes the aldehyde to a carboxylic acid

  2. Silver ion Ag+ is reduced to solid silver, Ag(s)

  3. Solid silver forms a film on the inner wall of the test tube, resembling a silver mirror
• Schiff’s reagent - prepared by passing sulfur dioxide into a solution of the dye fuchsin. The solution becomes colorless due to the formation of an addition product. Aldehydes abstracts sulfurous acid from the Schiff’s reagent and restores the pink color. The coloration is due to the formation of complex compound.
• Ketone - in general do not respond to this reaction. The reaction should not be subjected to heat. Some ketones give a light pink color with schiff’s reagent therefore light pink color formation is not a positive test.
• Schiff’s Test: a) Take the given organic compound to be tested in a clean test tube. b) Add 2-3 drops of schiff’s reagent. c) If there is instant pink or red color formation then the presence of aldehyde is confirmed.
• APPEARANCE OF PINK, RED OR MAGENTA COLOR INDICATES THE PRESENCE OF ALDEHYDE GROUP
• NaHSO4 - is a sodium salt of the bisulfate anion with chemical name Sodium bisulfate. It is also called Sodium acid sulfate or Bisulfate of soda or Sodium hydrosulfate. In its anhydrous form, it is hygroscopic. The solutions are acidic with a pH value of 1 for every 1M solution.
• Sodium acid sulfate - is a dry granular compound white in color. It dissolves in water and is corrosive to tissues and metals.
• FORMATION OF CRYSTALLINE PRECIPITATE CONFIRMS CARBONYL GROUP
• POLYMERIZATION - Any process in which relatively small molecules, called monomers combine chemically to produces a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three or more different compounds.
• Aldehyde - is an organic compound in which the carbonyl group is attached to a carbon atom at the end of a carbon chain.
• Physical properties The polarity of the carbonyl group notably affects the physical properties of melting point and boiling point, solubility, and dipole moment. Hydrocarbons, compounds consisting of only the elements hydrogen and carbon, are essentially nonpolar and thus have low melting and boiling points. The melting and boiling points of carbonyl-containing compounds are considerably higher.
• Aldehydes


  Important building blocks in organic chemistry
• Preparing aldehydes

  1. Oxidation

  2. Oxidizing primary alcohols to aldehydes (RCH2OH → RCHO, where R is an alkyl or aryl group)

  3. Passing primary alcohol over hot copper (Cu) or copper chromite (Cu[CrO2]2) catalyst

  4. Using pyridinium chlorochromate (PCC) reagent on a laboratory scale
• Most reagents that oxidize primary alcohols to aldehydes will oxidize the aldehyde further to a carboxylic acid
• Passing primary alcohol over hot copper (Cu) or copper chromite (Cu[CrO2]2) catalyst is less useful on a smaller scale such as in chemistry laboratories
• A method for reducing carboxylic acids to aldehydes (RCOOH → RCHO) in one step would be useful, but no general technique has been devised for accomplishing this. However, acyl chlorides, RCOCl can be reduced to aldehydes by several reagents, including lithium tri-tert-butoxyaluminum hydride, Li+H―Al−(OC[CH3]3)3.
• Aldehydes - are versatile compounds that can help make resins, dyes and organic acids, as well as perfumes for cologne, detergents and soaps. Of all aldehydes, formaldehyde is produced industrially on the largest scale
• TYPES OF ALDEHYDE

  -formaldehyde

  -acetaldehyde

  -benzaldehyde
• formaldehyde - is used for preserving tissue specimens and embalming bodies. It is also used to sterilize soil or other materials. - used in the manufacture of Bakelite, a hard plastic having high chemical and electrical resistance.
• Formaldehyde - is produced industrially by the catalytic oxidation of methanol according to the chemical equation:
• Acetaldehyde - (systematic name ethanal) is an organic chemical compound with the formula CH3CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants.
• Acetaldehyde - Use to control convulsions due various clinical causes including tetanus, status epilepticus and convulsive drugss
• Benzaldehyde (C6H5CHO) - is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. The primary component of bitter almond oil, benzaldehyde can be extracted from a number of other natural sources.
• Synthetic benzaldehyde - is the flavoring agent in imitation almond extract, which is used to flavor cakes and other baked goods
• KETONE Is a carbonyl group which is bonded to two carbon atoms. Has general structural formula RC=OR known for their sweet and sometimes pungent odors Low Boiling point Miscible with water
• ACETONE is known by the IUPAC name as propanone. other term 2-propanone or dimethyl ketone (CH3COCH3) liquid with a sweetish odor. Acetone is one of the few organic compounds that is infinitely Miscible in water (i.e., soluble in all proportions); it also dissolves many organic compounds.
• Acetone- For this reason—and because of its low boiling point (56 °C [132.8 °F]), which makes it easy to remove by evaporation when no longer wanted—it is one of the most important industrial solvents, being used in such products as paints, varnishes, resins, coatings, and nail-polish removers.
• Industrial Uses of Acetone Acetone is used as a solvent for acetylene, cellulose acetate, cellulose nitrate, celluloid, varnishes, lacquers, etc. - It is added to the natural gas fuel in the petroleum industry to give them better efficiency. - To remove the oil content from the water's surface in case of any accidental spill thus, saving marine life, which could have died due to depletion of oxygen. - For the safe transportation of highly flammable chemical fuel, acetylene. - In the electronic industry for cleaning small electronic gadgets.
• How acetone is prepared commercially

  1. Heat anhydrous calcium acetate

  2. Take fused calcium acetate mixed with iron filings in a retort

  3. Gently heat the reaction

  4. Shake distillate with sodium bisulfite solution

  5. Distill with sodium carbonate solution, dry over calcium chloride, and redistill
• (CH3COO)2Ca

  Anhydrous calcium acetate
• CaCO3


  Calcium carbonate
• The reaction produces acetone and calcium carbonate
• The distillate is purified by shaking with a saturated sodium bisulfite solution
• The purified acetone is obtained by distilling the sodium carbonate solution and drying over anhydrous calcium chloride
• Monocarboxylic acids - have just one carboxylic acid group (COOH) such as acetic, formic, propionic, and benzoic acid
• Types of monocarboxylic acid

  • Benzoic acid
  • Propionic acid
  • Stearic acid
  • Salicylic acid
• Benzoic acid - is an organic compound which is described by the chemical formula C6H5COOH. It consists of a carboxyl group attached to a benzene ring. Therefore, benzoic acid is said to be an aromatic carboxylic acid. This compound exists as a crystalline, colourless solid under normal conditions. The term ‘benzoate’ refers to the esters and salts of C6H5COOH.
• Physical Properties Benzoic acid has a colourless appearance in its solid state, which is of a crystalline nature. The crystal structure is monoclinic. The presence of the aromatic ring gives this compound a faintly pleasant odour. At a temperature of 130oC, the density of this compound reduces to 1.075 grams per cubic centimetre.
• Chemical Properties of benzoic acid

  It is soluble in water, and the solubility at 25oC and 100oC is 3.44 g/L and 56.31 g/L respectively. It is soluble in benzene, carbon tetrachloride, acetone, and alcohols. The acid dissociation constant (pKa) of benzoic acid corresponds to 4.2 Its reactions can occur at the carboxyl group or even at the aromatic ring.
• Uses of Benzoic Acid

  • Production of phenol
  • Used in ointments to prevent or treat fungal skin diseases
  • Used as a preservative in the food industry
  • Used in cosmetic products like lipsticks
  • Precursor to benzoyl chloride which is used in making other chemicals, dyes, perfumes, herbicides and medicines
  • Used in toothpaste, mouthwash, and face wash creams
  • Used in the manufacture of dyes and in insect repellants