Assiut University Faculty of Pharmacy Pharmaceutical Organic Chemistry Techniques & Glassware PDF

Assiut University 1 Faculty of Pharmacy Department of Pharmaceutical Organic Chemistry Pharmaceutical Organic Chemistry-1 For 1st year clinical students 2024/2025 Techniques & Glassware 2 ...

Assiut University 1 Faculty of Pharmacy Department of Pharmaceutical Organic Chemistry Pharmaceutical Organic Chemistry-1 For 1st year clinical students 2024/2025 Techniques & Glassware 2  Heating Drying Traps Techniques Filtration Decolorization 3  I. Heating 4 Heating Sources Bunsen burner -Traditional heat source used in chemistry laboratories. -Disadv.: a -Not suitable with inflammable liquids. b -Difficult heat control.  Water bath 5 Can be used with inflammable liquids with a boiling point less than 100 ˚C. Disadv.: 1- Water undergoes evaporation. 2- Incompatible Anhydrous conditions. 3- Water could be spilled.  Oil bath 6  Its main advantage over Bunsen burner that it Can be used with inflammable liquids of boiling point above 100˚C and up to 350° C. Disadv. Produce toxic fumes (if heated above its boiling point due to decomposition of oil). Greasy. frequent adjustment of temperature. Examples: 7 1- Medicinal liquid paraffin ( up to 220 °C). 2- Glycerol (up to 140-150 °C). 3- Cotton seed oil ( up to 250 °C). 4- Silicone fluid (> 250 °C). *Adv. of Silicone oil: Does not undergo discoloration if heated above its b.p.(c.f. other oils). *Disadv. of Silicone oil : Expensive  8 Air bath = Steam bath.  Can be used for heating liquids up to 100 °C, such as volatile oils  The difference bet. Air and water bath is……???  9 Sand bath  Adv.: Give temperature up to 300 ˚C.  Disadv.: The reaction can not be monitored.  Heating mantles 10 Most convenient mean of controlled heating of the reaction vessels that commonly used for distillation purposes. Adv.: In contrast to all previous heat sources, its use a heating mantle does not generate any liquid residue to drip off the flask. Also, generally distribute heat evenly over the surface of the flask and exhibit less tendency to generate harmful hotspots.  Electric hot plates 11 ▪Another heat source of reliable convenience. ▪Most suitable heating source for flat-bottom flasks.  Disadvantages Should not be used with inflammable liquids with low 12 boiling point (e.g., ether, light petroleum) when heated in open beakers (since ignition frequently occur).  13 A mixture of reactants and solvent is placed in a suitable vessel, such as a round bottom flask. This vessel is connected to a water-cooled condenser, which is typically open to the atmosphere at the top. The reaction vessel is heated in order to boil the reaction mixture; vapors produced from the mixture are condensed by the condense and return to the vessel through gravity. Used to thermally accelerate the reaction by conducting it at an 14 elevated, controlled temperature (i.e. the solvent's boiling point) and ambient pressure without losing large quantities of the mixture Adv.: Decrease loss of solvent by evaporation. Complete reaction within reasonable time span  15 Phenomenon common in chemistry  Bumping 16 A superheated liquid exists in a metastable state and tends to regain equilibrium through sudden vigorous vaporization which carries hot liquid along with escaping vapors. Sudden & Vigorous Heat source continue heating Boiling Bumping How to prevent bumping ? 17 A- Stirring Magnetic bars Glass rods (Stirrers)  18 B-Boiling stones Porcelain pieces superheating Kinetic absorption Xss. heat energy Movement of stones like continuous stirring  Important Notes 19 ❖ Boiling stones should be added before heating liq. Why???? ❖ Because, if added to a hot liq., it causes liq. to boil violently out of the flask as the superheated vapors trapped in liq. is released all at once. ❖If forget to add it before heating??? ❖Cool well below B.P. before addition. ❖If liq. require cooling & reheating, a new B.S. should be added before reheating??? ❖As B.S. carry liq. in their pores when cooled & doesn’t escape from pores. (exhausted)  Homogenous & steady heating 20 Continuous stirring X Bumping Boiling  II. Traps 21 Used to prevent toxic gases and vapors from escaping into the lab atmosphere. For example: A trap is used to absorb escaping HBr toxic gas which evolve in some organic reactions.  22 III. Filtration Filtration Simple=Gravity Buchner=Suction  Simple filtration Buchner filtration Driving force: gravity Driving force: suction To collect liquid To collect solid Slower rate Rapid rate Conical flask Buchner flask (Erlenmeyer flask) Filter funnel Buchner funnel 23  Simple (Gravity) filtration 24 Conical flask Folded (Fluted) filter paper Filter funnel (Erlenmeyer flask) Folded (Fluted) filter paper 25  26 Why we prepare fluted filter paper ?????? Large surface area, so increase filtration rate  27 1 2 3 4  28 Buchner (Suction) filtration Filtration (Buchner) flask Buchner funnel  29 1 2 3 4 5  30 6 7 8 9 10 11  31 Selection of Filter Paper Size that cover the perforation completely. The diameter should be slightly less than that of the entire funnel Should be moistened with few drops of clear supernatant (to cover & adhere completely to the plate) X Filter paper folds  32 *Uses !!!!! Used to collect desired solid or crystalline product *Advantages !!!! ▪ Rapid rate of filtration ▪ More complete removal of mother liquor  33 IV. Decolorization Removal of colored impurities by adsorption of impurities. Activated Charcoal. Only (1-2% ) is added to cold not hot soln. Decolorization  34 V. Drying For solids For liquids  35 Drying of Solids Removal of residual solvent (Organic or Water) By: 1.Air--- adv. Simple disadv. Slow, Liable to contamination and blown by strong air. 2.Oven--- adv. No contamination, fast and safe disadv. Melting may occur 3.Vacuum oven--- adv.( enhance the process) 4.Desiccator.  36 Drying of liquids Drying agents “Anhydrous inorganic salts” Reversible or Irreversible. CaCl2, Na2SO4, MgSO4, NaOH, KOH CaCl2 CaCl2.6H2O Na2SO4 Na2SO4.10H2O Reversible MgSO4 MgSO4.10H2O P2O5 2H3PO4 Irreversible 2Na 2NaOH  37 Notes ❑ CaCl2 can’t be used for drying: ❑ Basic soln. as Amines as it will react with them. ❑ Na2SO4 & MgSO4 are inert &neutral & most commonly used. Na metal is used for drying of ethers  38 Characters of ideal drying agent 1-Does not combine chemically with dried liquid. 2-Does not dissolve in the dried liquid. 3-Does not have any catalytic actions. 4-Should be economic. 5-Should have rapid action and effective drying capacity. 6-Should be easily removed from dried liquid by simple filtration.  39 Glassware  40 Separating Watch Glass Beakers Cylinders funnels 25/10/2021  41 Round bottom Flat bottom flask Stoppers flask 25/10/2021  42 Spatula Gauzes Test tube Racks 25/10/2021  43 Clamp & Clamp holder Test tube holder Clamp holder Clamp 25/10/2021  44 Handling of Glassware A-Cleaning B-Lubrication 25/10/2021  45 A-Cleaning 1- Cleaning dirty glassware can be achieved by using water and soap with aid of a brush. 2- but, if the glassware have resistant stain, this can be managed by using the cleaning mixture (Chromic acid mixture → Potassium dichromate”K2Cr2O7” + conc.H2SO4). This cleaning mixture have powerful cleaning action but must be used with great care since it is highly corrosive. 25/10/2021  B-Lubrication 46  What is lubrication?? (thin film) e.x: vaseline, glycerin, liquid paraffin, etc. 25/10/2021  Why we do lubrication? 1- to provide airtight seal. 2- to prevent glassware from being stuck together.  If the glassware stuck (fused) together; How to overcome this ????? 1- apply a thin film of glycerin. 2- tapping with the wooden hand of a spatula. 3- heating in a steam bath or water bath. 47 25/10/2021  48  Notes on the lubrication process 1- Too little amount of lubricant may give reversible results (freezing of glassware = stuck ). 2- Too much lubricant can contaminate the content of the glassware. 3- Before applying a new film of the lubricant, the old film must be removed (wiped-off) by apiece of tissue. 25/10/2021 49 25/10/2021