User:Moira M. Esson/Notebook/CHEM-581/2012/11/09

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Objectives

  1. Prepare solutions to run new PVOH based reactions
  2. Perform all calculations necessary for future PVOH reactions
  • First PVOH reaction will be the synthesis of polyvinyl acetate
  • Second PVOH reaction will be the attachment of 5-(4,6-Dichlorotriazinyl)Aminofluorescein which will be referred to as 5-DTAF

General Formula for reactions

Polyvinyl alcohol + [HAc]→Polyvinyl acetate

General Protocol for Polyvinyl acetate synthesis

  1. For a 1:1 ratio of polyvinyl alcohol OH groups to polyvinyl acetate dissolve ~1g PVOH inH2O
  2. Add ~1.36g HAc. Add ~2 drops of HCl to reaction mixture to catalyze reaction.
  3. Heat the reaction mixture to 40°C.
  4. Allow the reaction to stir for 1 hour
  5. Add sodium bicarbonate solution to the reaction mixture(titrate the reaction)
  6. Rotavap the remaining reaction mixture


Calculations

  • Overall, want to determine if have 1g of material how many moles of -OH groups. Once that is determined, will want to determine how many moles of -OH was reacted after the reaction.

Number of moles of OH groups in 1g PVOH: MW of repeating polyvinyl alcohol unit [C2H3OH]: 44.06g/mol

Polyvinyl alcohol repeating unit picture 

 1gPVOH(1mol PVOH unit/44.06g) x (1mol OH/1mol PVOH unit)= 0.022696 mol OH/g

Dye attachment calculations:

  • Want to react .01% of the OH groups with the dye

MW 5-DTAF dye: 495.28g/mol 

 (0.0227mol OH/g) x (.0001)= 2.27x10-6 moles dye



  2.27x10-6 moles dye x(495.28g dye/1mol dye)=0.001124g dye


Polyvinyl acetate synthesis calculations:

  • For all reaction mixtures, the total volume of the reaction mixtures will be 7mL
  • HAc will be the abbreviation for acetic acid


Density of HAc= 1.05g/mL (A.) 1:1 ratio 

  1g PVOH x (1mol PVOH/44g PVOH) x (1mol HAc/1mol PVOH) x (60g HAc/1mol HAc)= 1.36g HAc
  1.36g HAc x (1mL/1.05g HAc)= 1.295mL HAc

(B.) 20% ratio 

   1gPVOH x (1mol PVOH/44g PVOH) x (0.2mol HAc/1mol PVOH) x (60g HAc/1mol HAc)= 0.273g HAc
   0.273g HAc x (1mL/1.05g HAc)=0.26mL HAc

(C.) 40% ratio 

   1gPVOH x (1mol PVOH/44g PVOH) x (0.4mol HAc/1mol PVOH) x (60g HAc/1mol HAc)= 0.545g HAc
   0.5195g HAc x (1mL/1.05g)= 0.5195mL HAc

(D.) 60% ratio 

   1gPVOH x (1mol PVOH/44g PVOH) x (0.6mol HAc/1mol PVOH) x (60g HAc/1mol HAc)= 0.818g HAc
   0.818g HAc x (1mL HAc/ 1.05g)= 0.779mL HAc


Titration calcualtions:
(A.) Sodium bicarbonate solution preparation 

0.2L x (1mol/1L) x (84.01g/1mol)= 16.802g sodium bicarbonate.
  • Note: The actual amount of sodium bicarbonate used was 16.8046g. Also, it is not necessary to prepare this solution in a volumetric flask. Will standardize the solution to know the actual concentration.


(B.)Potassium hydrogen phthalate(PHP) needed MW PHP= 204.24g/mol 

1M PHP= x/0.1L
x=0.1mol x 204.24g/mol
x= 20.424g PHP needed


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