Preparation Sodium Pyrophosphate And The Properties And Nmr Spectroscopic Analysis Of Some Phosphate Species. Report Sample

Introduction

Sodium pyrophosphate (SPP) also known as tetrasodium pyrophosphate is a common chemical that is present in a number of products that we consume everyday. When pure SPP is a colorless transparent crystalline chemical compound with a formula Na4P2O7 . The molecular weight 265.902g/mol and has a melting point of 988 K. Characteristic spectrum to assess purity can be obtained from analytical measurements like IR and PNMR (Windholz, 1976).
The salt of pyrophosphate and sodium item as is twice that of table salt when ingested orally (Sigma Aldrich) so it is fairly non-toxic to humans. It has been used as a buffering agent, emulsifier, dispersing agent and thickening agent. It is common in such foods as chicken nuggets, marshmallows, canned tuna, cat foods as it can act as a taste enhancer (Lampila, 2013).
SPP has properties that can acts a water softening agent by removing calcium and magnesium from water and prevent calcium buildup on clothing and dishes. This SPP does also does similarly in the saliva thus reduce tartar on teeth and plaque (Maloney, 1966).
The aim of this study was to synthesize, analyze (using and discover the water softening properties of properties SPP. By carrying out the synthesis and understanding the properties of SPP it will allow the understanding of why this product can be used in so many different commercial products. As it is banned in some places it would be good to find another product to take its place with similar safety characteristics. However, we much firstly start with the original as a benchmark.

Experimental

All materials and laboratory equipment were provided in by the laboratory. All safety equipment was used. The procedure was outlined in the lab notebook and presented here in brief with any deviations

Synthesis Procedure

Procedure started by weighing 5.0 g Na2HPO4 H20 using a balance. After placing it in ceramic crucible heat was applied (approximately 240 deg C) with a bunsen burner for 1 hour. To test whether the reaction went to completion the material was dissolved in 2 drops of water and silver nitrate solution was added. Incomplete reactions give a yellow colour.

Recrystallization of the Product

Calculated Yield
Yield was calculated using the following equation:
2 HNa2PO4 → Na4P2O7 + H2O
Theoretical yield is 5 g x 1/ 141.96 g/mol =0.03522 moles
Actual Yield (grams) / Theoretical Yield (grams) x 100 % = Percent Yield

A vial containing was weighed without or product then with our product to determine the final weight.

Investigation of sodium triphosphate as a water softener
Results and discussion
After the reaction a final weight of 2.67 g (0.01004 g/mol) x 2:1 stoichiometry of SPP was obtained which gave a percent yield of 57 % based on 5 g of starting material.

The material was colourless transparent white powder with a similar consistency as one would find in baking powder or cornstarch.

‘Pyro’ is Greek for fire and in this reaction. By heating the sodium phosphate a condensation reaction occurs between the phosphate to make tetrasodium pyrophosphate. Pyrophosphates were originally prepared by heating phosphates (pyro from the Greek, meaning "fire"). Even chemists can appreciate that the pyrophosphate are widely used within biological reactions to make Adenosine-triphosphate from a phosphate and a pyrophosphate (Chi, 2000).

Investigation of sodium triphosphate as a water softener

After we added the sodium carbonate solution to both we noticed there was clouding to the solution without giving a milky. However, the sodium pyrophosphate solution does not change.
Ca2+ (aq) + 2NaHCO3 - (aq) ---> CaCO3 (s) + H2O + CO2 + Na

This called scale and coats the pipes of places that have hard water.

In the triphosphate solution the binds calcium and thus no precipitate is formed as calcium carbonate.
Among its many uses one common use is sodium pyrophosphate use of Sodium triphosphate as a water softener. Firstly, the SPP acts a alkalinity reducing agent in water. Secondly, SPP can bind a magnesium or calcium ion inactivating or sequestering them with precipitating in solution. In places with hard water there is a high concentration of calcium and magnesium calcium in the reservoir. The high content of calcium can absorb to plates for example. When the pyrophosphate is added to dish detergent it complexes with the calcium softens the water making the washing better (Borghetty, 1950). However, when they flush this water out it stimulates the growth of algae in waterways (Maloney, 1966). This is called eutrophication and although it might be good for algae it suffocates all other life.

Characterizing phosphate species in 31P and 19F NMR

31P-NMR spectroscopy can assay for impurities and assign structures of phosphorus containing compounds because they give well resolved signals. However it is much less sensitive to proton NMR but more sensitive to carbon NMR. Since it is a medium sensitivity nucleus that yields sharp lines and has a wide range. However, there is less decoupling and spin-spin couplings are not usually observed.
a. The Disodium hydrogen phosphate and sodium pyrophosphate are in the same environment and will not be distinguished as a single peak. The latter is shifted more downfield.
b. Sodium trimetaphosphate. It exhibits a single peak because it is symmetrical and the environment of one phosphate is not different from the others.

Diagram of trimetaphosphate

c. Sodium triphosphate
d. In the laundry detergent they have a polyphosphate a -20 ppm and pyrophosphate at -6 ppm.
e. There are five equivalent neighbors for the septet. PF6 will be at -150 ppm with a characteristic J coupling.

Conclusion

In our experiment we made pyrophosphates, looked into one of their uses to soften water and determined how to analyze their structure. With this laboratory we could use it to analyze different soaps or create new types of pyrophosphates for different purposes.

References

Borghetty, H. C., & Bergman, C. A. (1950). Synthetic detergents in the soap industry. Journal of the American Oil Chemists Society, 27(3), 88-90.
Chi, A., & Kemp, R. G. (2000). The primordial high energy compound: ATP or inorganic pyrophosphate?. Journal of Biological Chemistry, 275(46), 35677-35679.
Deshpande, S. S. (2002). Handbook of food toxicology. CRC Press.
Lampila, L. E. (2013). Applications and functions of food‐grade phosphates. Annals of the New York Academy of Sciences, 1301(1), 37-44.
Maloney, Thomas E. "Detergent phosphorus effect on algae." Journal (Water Pollution Control Federation) (1966): 38-45.
Windholz, M., Budavari, S., Stroumtsos, L. Y., & Fertig, M. N. (1976). The Merck index. An encyclopedia of chemicals and drugs (No. 9th edition). Merck & Co..