5 ms·

Potentially interesting article that gives up half-way through at the most interesting part to digress into an anti-anti-synthetic chemical rant. Not that I'm

Potentially interesting article that gives up half-way through at the most interesting part to digress into an anti-anti-synthetic chemical rant. Not that I'm against that, but I was really intrigued to learn why a chemical that has the properties of being reactive isn't reactive. The article just says that your body doesn't break it down. What does digestion have to do with it? If a molecule is reactive, then its reactive and should potentially react within the digestive system. So why doesn't it? That's the interesting bit that I was hoping to have answered and what the article seemed to be leading to until it stopped. In other words, imagine an article about cyanide that spent half of its time explaining all the parts of cyanide that could potentially react with organic chemistry, and then abruptly ended with "and your body absorbs it through the digestive system, so that's why it's bad." Unsatisfying, right? Also, why does the molecule look like insecticide or flame retardant? That isn't explained either. Does the fact that it has hotspots make it look like that? Or is there something more about its structure.

plus 10y ago
>Also, why does the molecule look like insecticide or flame retardant? Certain insecticides[0] and flame-retardants[1] are among the more infamous organohalides. Sucralose is also an organohalide. [0] https://en.wikipedia.org/wiki/DDT https://en.wikipedia.org/wiki/DDT [1] https://en.wikipedia.org/wiki/Tetrabromobisphenol_A https://en.wikipedia.org/wiki/Tetrabromobisphenol_A
kragen 10y ago
I'm not sure. I'm not a chemist, so I went and looked up a table of bond energies to see whether chlorohydrocarbons should actually be more reactive than the corresponding hydrocarbons, and it seems like the answer is actually yes, because the bond-dissociation energy isn't determined purely in isolation; the rest of the molecule affects it. A Cl-CH₃ bond has an energy of 339 kJ/mol, while the H-CH₃ bond has an energy of 431 kJ/mol, and the outrageously stable F-CH₃ is 452 kJ/mol. In isolation, the C-Cl bond has an energy of some 397 kJ/mol, while C-H is only 337 kJ/mol. I think typically the issue with reactive molecules is not that they react within the digestive system — if they're reactive enough to do that, then they may burn your mouth or even stomach, but they're unlikely to make it to your intestines without reacting with the rest of your food. The issue is typically that, if they get absorbed into your bloodstream, they can find their way to all parts of your body, and then wreak havoc on the one or a few particular molecules they react with. So apparently sucralose doesn't get absorbed into your bloodstream, and it's not so reactive that you get chemical burns, so it's harmless. And it doesn't get absorbed because it doesn't react with sucrase (or invertase), maybe because the big chlorine atoms bumping around there result in steric hindrance that keeps it from binding to the enzyme properly. As for insecticides and flame retardants, there is a large family of organochloride insecticides (including DDT), and organohalogens are common flame retardants, including the famous PCBs, but also things like HBCD. Both DDT and PCBs are notable not for being reactive but for being unreactive.

plus 10y ago

>Also, why does the molecule look like insecticide or flame retardant? Certain insecticides[0] and flame-retardants[1] are among the more infamous organohalides. Sucralose is also an organohalide. [0] https://en.wikipedia.org/wiki/DDT https://en.wikipedia.org/wiki/DDT [1] https://en.wikipedia.org/wiki/Tetrabromobisphenol_A https://en.wikipedia.org/wiki/Tetrabromobisphenol_A

kragen 10y ago

I'm not sure. I'm not a chemist, so I went and looked up a table of bond energies to see whether chlorohydrocarbons should actually be more reactive than the corresponding hydrocarbons, and it seems like the answer is actually yes, because the bond-dissociation energy isn't determined purely in isolation; the rest of the molecule affects it. A Cl-CH₃ bond has an energy of 339 kJ/mol, while the H-CH₃ bond has an energy of 431 kJ/mol, and the outrageously stable F-CH₃ is 452 kJ/mol. In isolation, the C-Cl bond has an energy of some 397 kJ/mol, while C-H is only 337 kJ/mol. I think typically the issue with reactive molecules is not that they react within the digestive system — if they're reactive enough to do that, then they may burn your mouth or even stomach, but they're unlikely to make it to your intestines without reacting with the rest of your food. The issue is typically that, if they get absorbed into your bloodstream, they can find their way to all parts of your body, and then wreak havoc on the one or a few particular molecules they react with. So apparently sucralose doesn't get absorbed into your bloodstream, and it's not so reactive that you get chemical burns, so it's harmless. And it doesn't get absorbed because it doesn't react with sucrase (or invertase), maybe because the big chlorine atoms bumping around there result in steric hindrance that keeps it from binding to the enzyme properly. As for insecticides and flame retardants, there is a large family of organochloride insecticides (including DDT), and organohalogens are common flame retardants, including the famous PCBs, but also things like HBCD. Both DDT and PCBs are notable not for being reactive but for being unreactive.