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

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Polyvinyl alcohol + [HAc]→Polyvinyl acetate
Polyvinyl alcohol + [HAc]→Polyvinyl acetate
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==General Protocol for Polyvinyl acetate synthesis==
==General Protocol for Polyvinyl acetate synthesis==
#For a 1:1 ratio of polyvinyl alcohol OH groups to polyvinyl acetate dissolve ~1g PVOH inH<sub>2</sub>O
#For a 1:1 ratio of polyvinyl alcohol OH groups to polyvinyl acetate dissolve ~1g PVOH inH<sub>2</sub>O

Revision as of 13:04, 30 November 2012

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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

Solution Preparations


(A.) Sodium bicarbonate standard

  1. ~16.802g sodium bicarbonate was measured and placed in a 200mL plastic container.
  2. 200mL of deionized H2O was measured using a graduated cylinder and was poured into the plastic container.
  3. The plastic container was sealed and the bottle was swirled vigorously until all sodium bicarbonate was dissolved.


(B.)PHP solution preparation

  1. 20.424g PHP was measured and placed in a 120°C oven for 1 hour to dry
  2. Dried PHP was placed in a 200mL volumetric flask with a magnetic stir bar and 100mL of deionized H2O was added to the flask
  3. A rubber stopper was placed on the top of the volumetric flask and the mixture was allowed to stir for 72 hours.


(C.)Reaction mixture preparations

  1. ~1g of PVOH was measured and placed in a 10mL beaker
  2. The necessary amount of deionized H2O was added to the beaker(7mL - the amount of HAc that would be added) and a small stir bar was placed in the beaker
  3. The beaker was parafilmed and set in a drawer.
  4. The following process was followed for each of the 4 polyvinyl acetate reactions

Actual amount of PVOH measured:

Ratio of polyvinyl acteate and polyvinyl alcohol Amount of PVOH(MW 22K) used (g)
1 to 1 reaction 1.0062
20% 1.0043
40% 1.0052
60% 1.0027



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