Chemistry 310 - March 26
a. DDT –
2. Pesticides -Can be either insecticides or herbicides
3. Insecticide kills insects, herbicides kills plants
i. would like it to be toxic enough for the target, but not to anything else
ii. like to be long lived, so you can spray and leave it there, but not water soluble
when rain comes.
iii. Don’t want to be water soluble and chemically reactive
iv. This is why DDT is very attractive
v. Prior to DDT, really nasty insecticides were used, especially with chlorine.
vi. Really toxic things like mercury sulfide, ACN arsenic sulfide was used, which
4. Organo chlorine – compounds were used because:
i. low solubility – they don’t have highly polar functional groups.
ii. Thermally stable
iii. Unreactive – when you take a hydrocarbon and replace C- H with Cl it become
more unreactive because it holds on to the bond more tightly. Major reason to
iv. This molecule is highly toxic, because of the tetrahedral C whihch is the the
most active C molecule. It blocks open the ion channels and destruct their
nursing. This is why it is highly toxic to a wide variety of insects.
v. Low vapor pressure – eg: DDT is a very heavy molecule and has a very high
vapor pressure. It has a 10 atm.
vi. When you put DDT (Dichloro diphenyl tri chlor ethane) into a reducing
environment – there are automatic processes which will lead it to it DDE. Which
kind of not oxidizes but leads to a velocity of Cl from the tetrahedral C. this is a
biological process which removes cl in our body. vii. DDE is not toxic to man, but it was not good for vitamin. It is a metabolate. It’s a
molecule that interfers with the tyrosine levels in birds. This was the problem
with the molecule because DDT was converted into DDE and body of birds was
affected with tyrosine levels.
viii. There is an argument that DDT should be used for the control of malaria.
ix. DDT was used as wonder molecule because it was not toxic for humans. It’s a
x. LOD =50Lethal oral dose- the amount needed to injest to kill 50% of the things)
– 0.1g/kg not highly toxic.
5. DDT was sprayed on cotton plants, fruit plants, and vegetables. One of the major driving forces
for this to get going was as a preventive measure of malaria – by getting rid of mosquitoes
6. In long island sound
a. [DDT] water 3pptrillion
b. plankton 40ppb
c. small fishppm
d. birds = 25ppm
e. This is called Bio magnification- taking a substance and concentrating it in the food web.
You are moving up the food web. The degree of biomagnification is described as a bio
concentration factor and it is simply a concentration of[ DDT] in birds/ [DDT] water = 25
x 10^-6/ 3 x 10^12- = 8x 10^6. Kow describes the bio concentration factor.
f. K for DDT = 2 x 10^6. This deals with an order of magnitude of two. This says that DDT
is soluble for the most part of the fatty tissues of the organism.
g. Kow – is the ratio between the concentration of the substance optimal/ concentration
of the substance in water.
h. This says that DDT is soluble for most part of the fatty tissues of the organism. The
partitioning needed to get into the fatty tissues is pretty well like a partitioning in the
solubility you have in the optimum. Fatty tissues are filled with long chain fatty acids.
i. This can be a thermodynamically driven system.
7. Slides DDT: 1
a. Concentration of DDT and DDE in breast milk. Its coming down substantially. Iy is
because of the ban in the 70’s. its got