Interesting article. I have always viewed Benzene as a bogeyman of sorts. My parents both interacted with it often throughout my life. My dad was a chemical engineer for an oil company, and he often spoke of spills and incidents. As a kid, I never understood what it was, but the tone and urgency were always something scary.
I also strongly suspect my mother's Benzene exposures (nurse cleaning lab slides with Benzene and no PPE) led to me battling Langerhans Histiocytosis throughout my childhood.
> Its peculiar behaviour, such as its surprising stability despite being highly unsaturated, hinted at a deeper mystery that would not be fully resolved until the mid-19th century with the proposal of its cyclic structure.
How were chemists in the early 19th century able to determine benzene must be highly unsaturated without knowing its structure? Did they simply combust it and measure the amount of water vapor and carbon dioxide produced?
The first step, as people have elaborated below, is combust the compound and measure the weights of various oxides, which (after the atomic masses of the relevant elements were settled around the 1820s) lets you work out the empirical formula of an unknown molecule. For benzene, this would tell you that there is 1 C : 1 H, but this doesn't tell you if it's C₄H₄ or C₆H₆ or C₁₁₁H₁₁₁.
The second step is to determine the molar mass of your compound, which requires finding something that depends on the amount of substance but not the mass directly. (In modern times, this is primarily mass spec). Back in the 19th century, this is probably abusing the ideal gas law, which lets you compute the number of moles in a gas given the pressure, temperature, and volume of a vessel. Combine this with the mass of that container, and you know how much a mole weighs. If you get out, say, 77g/mol, and you know that the ratio is 1 C : 1 H, well, the only formula that makes sense is C₆H₆ (which should ideally have 78g/mol, but you might not get the right answer for various experimental reasons).
What these early chemists accomplished with, to our eyes, extremely crude methods is astounding. Physical methods like weighing, burning and collecting residue; describing crystallization and precipitation behavior, even smelling (and sometimes tasting) was at one point a routine thing to do.
I'll admit I know very little chemistry, but I think the article would've been much better for people like me of it included any specific examples at all of benzene uses. It's filled with assurances that it's important and used all over the place but I didn't find that very enlightening.
It's kind of hard to explain how widespread a usage like "solvent" is. A huge amount of chemical reactions are most convenient to do in a liquid, a liquid that can dissolve the materials you're working with. That's a solvent. Benzene can dissolve a lot of things, including some that are really hard to dissolve otherwise. So it can be used for a huge variety of reactions, but as the sort background player that you might not pay attention to unless you can't have it.
It's a little like asking "what are the uses of water in chemistry", where you're tempted to answer, "um, everything?" Not quite, but not that far off either. (And with more cancer of course.)
Edit: disclaimer, I'm not a chemist, just an interested layman.
Benzene is used mainly as an intermediate to make other chemicals, above all ethylbenzene (and other alkylbenzenes), cumene, cyclohexane, and nitrobenzene. More than half of the entire benzene production is processed into ethylbenzene, a precursor to styrene, which is used to make polymers and plastics like polystyrene. Some 20% of the benzene production is used to manufacture cumene, which is needed to produce phenol and acetone for resins and adhesives. Cyclohexane consumes around 10% of the world's benzene production; it is primarily used in the manufacture of nylon fibers, which are processed into textiles and engineering plastics. Smaller amounts of benzene are used to make some types of rubbers, lubricants, dyes, detergents, drugs, explosives, and pesticides.
It's an important feedstock in the chemical industry but it is no longer used directly in household products. It used to be common in solvent/glue/grease remover formulations before the health hazard was widely appreciated.
Benzene was what made decaf coffee possible in 1905 (if can you consider this a productive use).
The beans were soaked in warm water then rinsed (several times?) with benzene, which was able to extract the majority of caffeine, and presumably not much else affecting the flavour.
It would have the benefit of evaporating with no residue given enough time, but due to the possibility of residue and the difficulty of working with it safely, decaffeination processes have since moved on.
I was a kid when there was a Benzene spill up where I lived at the time (Duluth, MN). I remember having to evacuate to our aunt's house out of town. My dad stayed at home doing yardwork until he felt "a little lightheaded" and finally joined us.
Seattle’s Gas Works Park has some strange equipment to address the benzene contamination. Bold move to make industrial sites into parks (it is one of the best in Seattle though!)
3.1 Benzene. On the east side of the Park, south of the Play Barn the groundwater is contaminated with benzene. An interim action removed a benzene containing LNAPL that had been discovered during site investigation. The remedy chosen for benzene was an air-sparging/soil vapor extraction (AS/SVE). The AS/SVE system covers approximately 1.5 acres of the Park. It is unnoticeable to Park users except for a small equipment box near the Towers. . An action level was calculated based on MTCA Method B surface water criteria and a dilution attenuation factor (DAF). The calculation used to set the DAF and the action level for benzene is given in appendix 1.
4.1 Benzene. Benzene concentration in the compliance well OBS-1 remains below the action level but above the method B groundwater cleanup level. The remedy, therefore, remains effective. See figure 3 below.
I've read that back in the day chemists used to nearly bathe in this stuff. Now it's rarely used in instructional chem labs. Heck as an undergrad in the 90's we were using Potassium Dichromate as an oxidizer. I spilled some on me and it ate through my lab coat and shirt beneath it. Probably should have had an apron on too...
Readit News
I also strongly suspect my mother's Benzene exposures (nurse cleaning lab slides with Benzene and no PPE) led to me battling Langerhans Histiocytosis throughout my childhood.
https://en.wikipedia.org/wiki/Langerhans_cell_histiocytosis
I posted similar photos of other polycyclic aromatic hydrocarbons (PAH) including napthalene, which are also mentioned in the article. [2]
In all, I had about 10 posts on PAH’s for laypeople and chemists who want to admire the structure of these fascinating saturated planar hydrocarbons.
[1] https://www.instagram.com/p/CxUs8YzO28Y/?igsh=NTc4MTIwNjQ2YQ...
[2] https://www.instagram.com/p/CxFCSueOrA2/?igsh=NTc4MTIwNjQ2YQ...
* 1,3,5-tris(biphenyl)benzenei -- https://www.instagram.com/p/CxZgDpWLk2b/
* hexa-cata-hexabenzocoronenei -- https://www.instagram.com/p/CxW0-PkRbK4/
* rubrene -- https://www.instagram.com/p/CUdK6MhPw9p/
* coronene -- https://www.instagram.com/p/CxRfv6yx0VL/
* tetracene -- https://www.instagram.com/p/CxHuVt2uKBk/
* dibenz[a,j]anthracene -- https://www.instagram.com/p/CxKLUXTOq2o
* benzene -- https://www.instagram.com/p/CxCtSEWOEuu/
* summary of 10 molecules in pen and ink -- https://www.instagram.com/p/CxbtJZHPGGL/
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How were chemists in the early 19th century able to determine benzene must be highly unsaturated without knowing its structure? Did they simply combust it and measure the amount of water vapor and carbon dioxide produced?
The first step, as people have elaborated below, is combust the compound and measure the weights of various oxides, which (after the atomic masses of the relevant elements were settled around the 1820s) lets you work out the empirical formula of an unknown molecule. For benzene, this would tell you that there is 1 C : 1 H, but this doesn't tell you if it's C₄H₄ or C₆H₆ or C₁₁₁H₁₁₁.
The second step is to determine the molar mass of your compound, which requires finding something that depends on the amount of substance but not the mass directly. (In modern times, this is primarily mass spec). Back in the 19th century, this is probably abusing the ideal gas law, which lets you compute the number of moles in a gas given the pressure, temperature, and volume of a vessel. Combine this with the mass of that container, and you know how much a mole weighs. If you get out, say, 77g/mol, and you know that the ratio is 1 C : 1 H, well, the only formula that makes sense is C₆H₆ (which should ideally have 78g/mol, but you might not get the right answer for various experimental reasons).
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https://en.wikipedia.org/wiki/Kaliapparat
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It's a little like asking "what are the uses of water in chemistry", where you're tempted to answer, "um, everything?" Not quite, but not that far off either. (And with more cancer of course.)
Edit: disclaimer, I'm not a chemist, just an interested layman.
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Benzene is used mainly as an intermediate to make other chemicals, above all ethylbenzene (and other alkylbenzenes), cumene, cyclohexane, and nitrobenzene. More than half of the entire benzene production is processed into ethylbenzene, a precursor to styrene, which is used to make polymers and plastics like polystyrene. Some 20% of the benzene production is used to manufacture cumene, which is needed to produce phenol and acetone for resins and adhesives. Cyclohexane consumes around 10% of the world's benzene production; it is primarily used in the manufacture of nylon fibers, which are processed into textiles and engineering plastics. Smaller amounts of benzene are used to make some types of rubbers, lubricants, dyes, detergents, drugs, explosives, and pesticides.
It's an important feedstock in the chemical industry but it is no longer used directly in household products. It used to be common in solvent/glue/grease remover formulations before the health hazard was widely appreciated.
The beans were soaked in warm water then rinsed (several times?) with benzene, which was able to extract the majority of caffeine, and presumably not much else affecting the flavour.
It would have the benefit of evaporating with no residue given enough time, but due to the possibility of residue and the difficulty of working with it safely, decaffeination processes have since moved on.
https://en.wikipedia.org/wiki/1992_Nemadji_River_train_derai...
Edit: better link https://apps.ecology.wa.gov/cleanupsearch/site/2876
Original link was older 2005 report: https://apps.ecology.wa.gov/cleanupsearch/document/1509