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Author: Subject: Bromo-DDT, p,p-dibromo-diphenyl-1,1,1-trichloro-ethane
XeonTheMGPony
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[*] posted on 10-2-2020 at 16:37


Quote: Originally posted by unionised  
Quote: Originally posted by XeonTheMGPony  


there is a natural form and synthetic,

There are natural pyrethroids but I doubt permethrin (with two chlorines in the structure) is natural.


exactly natural form with the y Pyrethrin, artificial with the e

y one is safe with cats, the synthetic how ever works the best.
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Dr.Bob
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[*] posted on 10-2-2020 at 20:07


I found a 1 lb bottle of DDT from ~1960 when cleaning my parents house out. I'll save it for emergencies, but nice to know I have an antique. Fipronil is also quite toxic to bees, but for some reason it has been largely ignored in the press. It does work well on termites, which is useful.

I still find it a shame that Chlordane (which was banned for most everything years ago) was not allowed to be used still for termite control, as one treatment would protect a house for 40-50 years, which is far longer/better than any other pesticide, and it binds very tightly to clay, so ideal in the south, and it barely ever leaches out of the clay into water, so ideal for the South. They used Chloropyrophos for a while, which is incredibly toxic to most living creatures, but it has a short half life in soil, and leaches in to water more. Now they mostly use fipronil, imidacloprid, or hexaflumuron bait, all of which have pros and cons, but none lasts 50 years. All have different modes of action, so each works better in some situations. Chlordane was both a repellant and a toxin, so termites stayed away from it, much like pyrethroids.

Another neonicotine analog of imidacloprid was Thiamethoxam, which uses a previously unknown starting material, (2-Chloro-1,3-thiazol-5-yl)methyl bromide, which turned out to be a neat optimized synthesis, almost trivial, from several cheap chemicals, and the product is autocatalytic to the reaction, so your yield goes up each time you use the same reactor. Sadly, China had already started selling copies of it on the black market before it even got through the EPA, so I saw adds for it before it was even legal to use, and before the inventor could even start selling it legally. It had been thought that the pyridine in nicotine was critical to the toxicity, but that proved incorrect, as several other heterocycles work.

Hexaflumuron works as a chitan growth inhibitor, so the bugs grow in their shell until they crush themselves as the shell cannot grow larger. It makes a great bait, as termites spread it around, and it takes a long time to kill them, so they can spread it into the colony before it hurts them. If you simply treated the sill plate of a house with it, you could potentially have a baited house that would kill all termites, but that would cut out the pest control companies, so they did not like that idea. Since that wood is enclosed in the final house, it would not be exposed to any insects other than those eating through the sill plate. But that still seems like a great way to avoid termites, without exposing the environment to it. Termites cannot detect it, unlike treated lumber (which they avoid or go around in mud tunnels), so they would eat enough to kill the colony in theory.

I guess you might be able to tell I was a chemist who had termite problems once... I found the literature hard to find and read, but eventually realized that many of those compounds could be made readily but you had to understand how to use them to make it worthwhile. Fipironil is not very easy to make, BTW, so I would try hexaflumuran (you can also buy it readily now) or just buy one of them mail order. It would be hard to make some of the cheap enough now that the market is flooded with cheap Chinese generics, but this is one case where I am not worried about the quality of the generic product. (I have seen photos of some Indian generic drug "factories", some of which had birds living in the roof or holes in the walls allowing in rodents. Yeach.
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Tsjerk
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[*] posted on 10-7-2020 at 03:46


Quote: Originally posted by Tsjerk  
If I would run this synthesis again I wouldn't use an excess of bromobenzene again... I had the gut feeling it would evaporate quite easily, but it seems to be quite persistent. I still didn't get it to fully crystallize and I suspect the bromobenzene to be guilty for that. I could pull I vacuum but that would mean more dirty glass and more mechanical losses.

What I have now is a slush of crystals. The DCM seems to be long gone, but there is some liquid junk.

Maybe I will just poor boiling water over it, it might separate.

Edit 2: And I would use double the amount of sulfuric acid. The volume of product I have after evaporating for more than a day is almost halve the volume of the oily liquid I had after first poring the reaction on ice. I guess there was to much water in the reaction, most preparations are done with a bit of oleum and anhydrous chloral, although it should be doable with just 96% sulfuric acid and the hydrate of chloral.


I ran the reaction a second time with twice the amount of sulfuric acid and a smaller amount of bromobenzene. I think I used about 2.025 eq. bromobenzene compared to the chloral and 250 ml of sulfuric acid.

The yield still sucks (23%) and is comparable to the yield with half the sulfuric acid, but the product seems a lot cleaner. This time I just filtered the crashed product and dried it. I boiled in about 100 ml methanol and filtered after cooling. The product seems more crystalline. The melting temperature is somewhere above 100 degrees.
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Tsjerk
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[*] posted on 25-7-2020 at 03:44


I made an emulsion because I thought the evaporation method was a bit crude and a lot of Br-DDT was decomposing.

I dissolved a gram of Br-DDT in 20 ml of mineral oil with a bit of heating. With strong magnetic stirring I mixed this with about 30 ml of water and a couple of drops dish wash detergent. I got a white emulsion that didn't separate, this was diluted to 750 ml, the suspension slowly floats up, but never really separates, a quick shake suspends it again.

This mix in a plant spray works really well for dispersal of the Br-DDT.
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Tsjerk
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[*] posted on 9-12-2020 at 07:28


The emulsion works really well. Now and then I have some pest growing, mostly on new parts of plants or on new plants coming in. I'm still using the gram of Br-DDT emulsion made in July. I really only have to spray once whenever I see something. After that it's gone.
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[*] posted on 9-12-2020 at 19:55


How did you acquire chloral hydrate? Where I live it is prescription only for insomnia and I haven't really heard of a successful synthesis of it so far. I hear of people chlorinating ethanol but it seems like most attempts are just failures.



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[*] posted on 10-12-2020 at 02:43


I bought it from Mario.
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morganbw
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[*] posted on 10-12-2020 at 19:37


Quote: Originally posted by aromaticfanatic  
How did you acquire chloral hydrate? Where I live it is prescription only for insomnia and I haven't really heard of a successful synthesis of it so far. I hear of people chlorinating ethanol but it seems like most attempts are just failures.


Look this over, I have not done this but this is what I would attempt if I were needing homemade chloral hydrate.

chloral hydrate synthesis

[Edited on 12/11/2020 by morganbw]
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[*] posted on 10-8-2021 at 13:29


I tried something different to dispers the DDT, I dissolved about 200 mg in petroleum ether, bp 60-80, and added that to about 200 ml water, a drop of soap and a pinch of TBAB.

I don't know whether the soap and or TBAB did anything, but with strong magnetic stirring and heating until all PE evaporated there was a very fine mist of white solid in suspension. Some of the DDT formed bigger crystals, and the fine solid very slowly settles, but a shake quickly brings it back in suspension.

I now use this in a spray bottle. Only one annoying species of wooly aphid seems not to care too much about the stuff. But other than that no more pests in my greenhouse. 1% ethanol is doing fine against the woolly buggers though.
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