[melikeisgoren]

Im working with an organic pesticide (malathion).I am trying to remove pesticide from water with a wet oxidation process. but while I was trying to see the effects of ph on removal efficiency I realize that pesticide is completly removes after   setting ph 11 with NaOH . I observe the malathion consantration after treatment with HPLC.I check the same  sample malathion consantration also with LC MS-MS . But there was no malathion in the sample. So can you explain me what happens to the malathion (pesticide) when we make ph adjustment with NaOH.

[Arkcon]

From the MSDS, Malathion is rapidly hydrolyzed by pH greater than 7 or less than 5.  Which is weird, because the stuff is itself pH 3.5 in 50 % solution.  At any rate, yeah, you're going to have to be very gentle with this compound, its used because it so easily decomposes, so don't remain poisonous in the environment for long.

[AromaticAcrobatic]

So can you explain me what happens to the malathion (pesticide) when we make ph adjustment with NaOH.

At pH 11 with NaOH, the highlighted esters will be transformed to carboxylic acids(which is the same molecule except the highlighted areas are replaced with OH).

 

[Babcock_Hall]

Phosphate triesters are labile to hydrolysis.  The presence of a phosphorus-sulfur double bond will slow down the hydrolysis rate, relative to the same compound with a phosphorus-oxygen double bond.

[AromaticAcrobatic]

Phosphate triesters are labile to hydrolysis.  The presence of a phosphorus-sulfur double bond will slow down the hydrolysis rate, relative to the same compound with a phosphorus-oxygen double bond.

That's good to know, I didn't know that.