Photolysis of Raxil DS2 in aqueous solution by sun light through transition state computational study

الملخص

Transition state study have been carried out through computational methods to
investigated photolysis of Raxil DS2 in aqueous solution by sun light . Quantum
methods (semiemprical &Ab-initio included in packaged Hyper Chem 6.02 program)
have been used to determine the chemical structures and physical properties of the
pesticide molecule , intermediates ,and the all probable transition states structures
involved in the first cleavage step reaction.
Energetic properties and chemical reactivity was calculated for every chemical
moieties that’s participated in the photolysis reaction through surface potential energy
calculations . Initiation steps of photolysis have been studied theoretically for the
main bonds in pesticide molecules through surface potential stability calculation .
Several transition states are suggested for all probable main bounds that’s giveup
the first cleavage step of photolysis ,they are examined by the calculations of
surface potential energy, to estimate the heat of formation, energy barrier, and Zero
point energy .calculations are carried out by study the structures of all suspected
fragments that are produced from these transition states. Heat change for complete
photolysis reaction has been estimated computationally to know heat formation for
every chemical component participated in this reactions.
In the present work ,it has been found that Raxil DS2 pesticide have very
reactive chemical bonds ,since it undergoes photolysis through C10-C12 bond by real
transition state with energy barrier equal to 31.175 kCal mol -1 ,that’s equal to energy
light of wave length of 916.440 nm .The first initiation step of photolysis reaction is
endoenergetic with given up Two free radicals at 35.426 kCal mol-1 . completely
photolysis reactions of Raxil DS2 in aqueous media is exothermic reactions with -
656.6945 kCal mol-1 . Fifty six mole of water molecules are needed to Transform the
pesticide molecule into sixteen mole of carbonic acids , hydrochloric acid , nitric acid
, and hydrogen gas.