Diazomethane: a poisonous explosive yellow gas
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Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations

From patient to flask: Temozolomide (the standard of care for glioblastoma) and other imidazotetrazine compounds are repurposed into synthetic reagents. The prodrugs release alkyl diazonium species under aqueous conditions and were thus employed to conduct the two most widely used reactions of diazomethane, esterifications and cyclopropanations.

Abstract

Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metalโ€catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is nonโ€explosive and nonโ€toxic, and should find broad utility as a replacement for diazomethane.

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What safety precautions would you guys take in handling diazomethanes, specifically TMS-diazomethane?

Do any of you guys have experience with this stuff? I am kinda scared of this stuff. D:

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Trying to Avoid Diazomethane? See: "Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations" reddit.com/r/ACIE/commentโ€ฆ
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A funny blog post about how NOT to handle diazomethane! From Derek Lowe on Science Mag's blog blogs.sciencemag.org/pipeโ€ฆ
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Just made "some" N-Nitroso-N-methylurea the direct precusor to diazomethane. labphoto.tumblr.com/post/โ€ฆ
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The most recent Aldrichimica Acta just issued: Open-access reviews of Photocatalytic C-F activation and Diazomethane generation sigmaaldrich.com/content/โ€ฆ
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"Diazomethane may explode in contact with sharp edges..."

reads the wikipedia article for Diazomethane (http://en.wikipedia.org/wiki/Diazomethane#Safety)

Can anyone here help explain why this would be the case? How would this spacial property cause a volatile gas to explode? Any info is greatly appreciated

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"Deaths from diazomethane poisoning have been reported. In one instance a laboratory worker consumed a hamburger near a fumehood where he was generating a large quantity of diazomethane, and died four days later from fulminating pneumonia." en.wikipedia.org/wiki/Diaโ€ฆ
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Diazomethane derivitizations, need you help figuring something out.

So, the lab I am working in, we have been trying to derivitize AMPA (aminomethylphosphonic acid; http://umbbd.msi.umn.edu/core/graphics/c0136.gif) with Diazomethane to increase sensitivity on the LC/MS/MS. The problem is, we are having a LOT of trouble with the derivitization, and we believe it may be the fault of the primary amine being protonated rather than the alcohols on the molecule. Is there any way we might be able to block the reactivity of the amine to methylate the alcohol groups which is still reversible in a way that would not hydrolyze the methoxy groups formed from the derivitization?

edit: the problem with the amine being protonated is that the diazomethane synthesis works best in acidic conditions

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Boron's crazy properties and its synthetic uses

I'm sure that recently many of you have noticed me raving about boron and specifically boric acid and this is here to show you that I have in fact not fallen in love with the letter "B" but rather have found the most wild element on the periodic table. Boron compounds range from some of the strongest reducing agents known (and no I'm not even talking about borane or borohydride), oxidizers that make fluorine scared, and acids that will protonate essentially anything they come into contact with (the strongest super acids known).


To begin we should go over some elemental properties of boron. It is a metalloid, has a high affinity for oxygen, is unreactive in its elemental form, has 8 oxidation states (-3 to +3 and an additional partial oxidation state that is fairly irrelevant), and has an electronegativity of 2.2 which is 0.2 lower than hydrogen. The oxidation states, it's electro negativity, and its oxygen affinity are very interesting properties. As general compounds boron is non-volatile as an oxide but volatile in most other forms. Boron-oxygen bonds can be displaced under the correct conditions, similar to carboxylic acids. Boron compounds are also lewis acids (this is an extremely important property we will discuss more later).


Oxidation states:

We will cover 5 of the oxidation states as the rest are either too unstable or too boring to be of any use.

0: The zero oxidation state is fairly stable and only reacts with strong oxidizers or extremely strong reducing agents (eg. molten magnesium metal).

-3: This oxidation state is exclusive to metal-borides. It is a strong reducing agent (though surprisingly not the strongest). It is fairly stable and has decent mechanical properties. It can be used to make borohydrides by refluxing in alcoholic hydroxide solution (inefficient; yields of 5-30%) or borane adducts by adding to liquid ammonia saturated with HCl.

+3: This state is extremely stable and is the form that boric acid is in. Boron cannot be oxidized from here and cannot oxidize compounds without a huge amount of energy (~1 MJ). This state is extremely lewis acidic and capable of backbonding, forming 1:1 adducts with liginds, and other properties we will get into when we discuss borates.

+2: This state is very stable ... compared to boron. It is half as stable as the +3 state and considering the difference is about 1 MJ there is huge reduction potential. For example diboron tetrahydroxide ca

... keep reading on reddit โžก

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Properties and synthesis of energetic boron-(nitrogen or carbon)-hydrogen polymers

So a little preface: Energetics are not really my passion though in creating a strong reducing agent it appears as though I have designed a synthesis of an extremely energetic compound. This is my first post here though I am by no means new to chem. I am quite active on another chem sub though they wish to remain unnamed (just look in my post history). This compound could be tuned to the needs of the user and is made from relatively available materials. My main goal is to see if anyone can help me predict the properties to avoid accidentally blowing myself up while testing the reducing properties though extreme precautions will still be taken with any testing. Anyways....

The compounds in question are 1,3,5 triborabenzene, a new compound I am calling boreyne (H-C-B with the C-B bond being a triple bond; this compound likely quickly polymerizes into triborabenzene or an even larger highly ordered polymer), and a variety of poly-boron-hydrazides. These compounds would obviously need to mixed with a large amount of oxidizer though due to their extremely high lewis acidity they may be pyrophoric (specifically boreyne). Each compound requires 8 electrons to be removed per monomer for complete oxidation/combustion which lines up quite nicely with dinitrogen pentaoxide or perchlorate salts (including the base chlorine that all the oxygens are bonded to).

As far as I know the only compound in this family that has been synthesized is the polymeric boron hydrazide which is (scarily imo) made by simply refluxing boric acid and anhydrous hydrazine (could be subbed for an anhydrous borate salt and hydrazine HCl; the paper only used anhydrous hydrazine though hydrazine hydrate will also likely work). They said nothing of the properties of the compound other than it has a high melting point (indicating polymer rather than aromatic), that it is water soluble (unsure if it is stable though), and that it has a molecular formula of H5BN4 (very nitrogen rich; boron has more violent combustion with oxidizers than carbon).

The carbon based polymers could be made by the addition of formates or carbon monoxide and subsequent dehydration. This reaction is more similar to pyrosis in this case due to the release of nitrogen gas and a C-bora-diazomethane intermediate; the intermediate would have a structure such as this: N^- =N^+ =C-(H)-B. Overall a boreyne monomer is formed which would either immediately combust, immediately coordinate to nitrogen gas, or would polymerize into a

... keep reading on reddit โžก

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The danger of using distillation glassware with ground-glass joints

Diazomethane allows for the esterification of carboxylic acids via an Sn2 attack of the nucleophillic oxygen on the electrophillic carbon of diazomethane. The by-product of the reaction is nitrogen gass, the releaseof this gass makes the esterification reaction, which is normally reversible, irreversible. Therefore the use of diazomethane as reagent for esterification is highly favoured over other reaction pathways for the esterification of a carboxylic acid.

However!, when diazomethane is needed, it has to be prepared in situ (in your flask) as the reagent is too explosive to be handled purified. It is often generated by using a precursor agent and distilling the solution of diazomethane. Here arises a problem!

Normal glassware used for distilling often uses ground glass joints, the purpose of which is to generate friction between connected glassware which allows for an air-tight seal. In your lab days, often you have spilled some reagents over these joint but this didn't really matter.

----
But with this particular reaction it does!
The friction generated by the ground-glass joints will, in case of working with diazomethane, generate enough energy to initiate an explosion!

To counter-act this, you have to use special glassware with clear joints!, these will generate no to minimal amounts of friction when compared to the normally used ground-glass joints. :)

TL;DR
Diazomethane is an explosive reagent, prepared in situ by distillation. The ground-glass joints on normal glassware will generate enough friction to set off an explosion of the reagent, therefore one needs to use a special kind of distillation setup, with clear joints to minimalise the chance of the whole setup exploding during distillation.

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Courage (ๅ…ƒๆฐ—)

Mining is not the most exciting job in the cluster or the best pay at the end of the year, but itโ€™s honest, mostly safe, it gives asylum and a chance at earning a salary to undesirables, and can be fun depending on the colleagues. We were mining hydrocarbons on an Ice planetoid in a remote area of the galaxy, near the border with the [Empire of the twelve suns]. Being humble laborers like ourselves we didnโ€™t worry too much about our security, those worries were handled by both a private conglomerate contracted by [Mohole Inc.] (our company) and the [Republic of Xarn] outpost right behind the corner of our outpost, at a mere [0.2 ly]. Our crew was composed of mostly omnivores, and some herbivores. Nothing too fancy, good people, hard workers, honest folks.
One of them was Jim, the Human. Humans were a new species in the quadrant, the first crew had arrived just around [40.45 years] ago and Jim was the first employee to work with us. Jim was always happy, always joking about the hardships of his work, always mock-complaining about everything and everyone, making the hours fly, and the fatigue bearable.

One fine [monday] we had just started the second shift when the alarm started. This code was actually new, it wasnโ€™t the fire alarm, the tectonic shift alarm, a water or chemical spill or anything else they trained us for, so there were a couple of minutes of doubt while the shift supervisor checked in with the direction center through the intercom. The alarm signified โ€œWar/total lockdownโ€. It meant that the outposts were facing a military force, It meant that we were soon to be under siege.

During the next two weeks, we proceeded to seal every exit and every system that needed access with the outside, while the security team was doing their best to establish choke points and prepare weaponry near the vulnerable points and around the sleeping quarters, where some of the workers were already stockpiling rations and water.

In the beginning, everything seemed so futile, no-one was taking it seriously, not a single shot had been heard or seen by the automated security systems outside, or the orbital satellites. The q-net said there was intense fighting around the outpost in our vicinity, but apparently, this invasion force was small and more of a โ€œprobeโ€ the Empire was using to test how much they could get away with before the whole Republic would react in an all-out war. It turns out that the Republic was ready to tolerate a lot before declaring war, and bot

... keep reading on reddit โžก

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"A Practical Synthesis of Dichloroacetylene"

Practical indeed, but with caveats. Thought I'd show 'n' tell here for gits and shiggles, originally on ex&f.

https://doi.org/10.1021/jo00391a059

TL;DR, it's viciously toxic, carcinogenic, teratogenic, reasonably pyrophoric and decomposes explosively at its STP bpt.

We had a visiting professor who decided to make a couple of moles after retro-ing his way back to a synthon for some cross-coupling that appeared to be neatly solved by this little beauty. He had quite the fire after carelessly disassembling his vacuum distillation rig, which is when we found out what he was up to... fortunately that lab used argon, not nitrogen, and only the paperwork was a killer.

Talk about a scale up; from the paper at 10mmol:

>Warning - although we have used the following procedure repeatedly without the slightest incident, it is strongly recommended that all work with dichloroacetylene be conducted in a good hood and behind a safety shield.

No sh*t. Took me back to the diazomethane days.

I love argon.

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Huisgen's 1,3โ€Dipolar Cycloadditions to Fulvenes Proceed via Ambimodal [6+4]/[4+2] Transition States

Ring, ring : Computational studies with density functional theory (DFT) of Huisgen's 1,3โ€dipolar cycloadditions and variants subsequently developed by others show that they involve ambimodal [6+4]/[4+2] transition states. Intriguingly, the ambimodal transition state with the nitrile ylide gives both products, favoring the [6+4] adduct, as found experimentally, while the diazomethane reaction is predicted to give only the [4+2] adduct.

Abstract

Huisgen's 1960 announcement of the concept of 1,3โ€dipolar cycloadditions was published the year before Alder's study of the reaction of diazomethane and dimethylfulvene. The diazomethane reaction was studied again in 1970 by Houk etโ€…al. and shown to give a [6+4] adduct. Padwa's nitrile ylide cycloaddition to dimethylfulvene (1978) gave [6+4] and [4+2] adducts. We performed computational studies of these reactions with density functional theory (DFT) and show that they involve ambimodal [6+4]/[4+2] transition states that can lead to either type of cycloadduct from one transition state. We dedicate this paper to the extraordinary life and humanity of Rolf Huisgen, and to the undying influence of his discoveries on chemistry.

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What are you working on? (#realtimechem)

Hello /r/chemistry.

It's everyone's favorite day of the week. Time to share (or rant about) how your research/work/studying is going and what you're working on this week.

For those that tweet: #realtimechem

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"Practical synthesis of dichloroacetylene." Practical, yes, but.

More war stories anyone?

We had a visiting professor come to work in our lab from a well known southeast-asian university. We'd had a mixed bag from that particular institution but this chap was really fantastic. Great chemist, hilarious, ingenious, fitted in like a glove - some of his more advanced synthetic skills were a bit lacking and we had some communication issues, but all was going well.

Fast forward a bit. Our stressy post-doc comes running in from the other lab. "Bob's had a fire, there's a fire, it's a distillation..."

In order to solve his Pd cross-coupling route Bob* had retro'd his way back to dichloroacetylene. When he read the paper I'm not sure what part of his brain missed the fact he was about to prepare something truly terrifying at large scale, but he diligently set about making and distilling masses of this liquid. And not doing any sort of risk analysis. Or indeed telling anyone at all.

So I follow our post-doc into the other lab, along with a fire extinguisher, big gloves, face mask and a couple of gawkers. There's a partially disassembled 500mL / vigreaux fractionation rig pouring out stringy black acetylene-looking smoke, filling the fume hood with this dark mess. I reach in, slot the distillation flask back on and turn up the argon and the fire settles immediately, then goes out. I also stopper his collection flask, which he'd apparently removed at first sign of trouble.

Turns out stoppering that flask is one of the better things that happened that day. I had no idea at the time but there was some hundred mL of pure dichloroacetylene, toxic as hell and known to explode on contact with air, protected by nothing more than a delicate layer of argon which had been fortunately undisturbed by the shenanigans. Sure, the distillation residues and stuff in the column had gone bat shit mental on disassembly, but that was nothing compared to what could have been.

--- Sorry if this is boring, but there are a number of points we should mention ---

  1. Dichloroacetylene explodes at it's STP boiling point. Vacuum distillation is therefore required but with standard glassware is utterly retarded at any significant scale. Ground joints, air leaks, hot surfaces, cracked glass... Come on, bulk distilling toxic explosives, really? We grew out of that one with diazomethane.
  2. It's rather fortunate that the lab used argon, not nitrogen. Argon, being heavier than air, forms a blanket, protecting the product and extinguishing the fire. Nitrogen
... keep reading on reddit โžก

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Has anyone worked with Trimethylsilyldiazomethane (TMSD) NEED HELP!

Hi,

I want to methylate the phosphate groups on a bisphosphonate moiety using TMSD for LC-MS/MS as I have read about the success in many papers and the reaction seems to be quite simple. No one in my lab group has ever used TMSD.

However, I am a first year masters student and have never worked with a chemical before that needs to be stored under nitrogen. My background is also in health sciences and not chemistry, so I am unfamiliar with some of these processes. How do I even store a chemical under nitrogen?

Now I am paranoid that if I open my vial of TMSD in air at all it will degrade or react in the air. I am also unsure if all the reaction steps need to be carried out in an inert environment? Has anyone worked with TMSD or diazomethane before?

Any help or tips is immensely appreciated!

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Predicting Absolute Rate Constants for Huisgen Reactions of Unsaturated Iminium Ions with Diazoalkanes

The kinetics and stereochemistry of the reactions of iminium ions derived from cinnamaldehydes and MacMillanโ€™s imidazolidinones with diphenyldiazomethane and aryldiazoยญmethanes were investigated experimentally and with DFT calculations at the (SMD=DCM)//B3LYPโ€D3BJ/def2svp level of theory. The reactions of diphenyldiazomethane with iminium ions derived from MacMillan 2nd generation catalysts gave 3โ€arylโ€2,2โ€diphenylcyclopropanecarbaldehydes with yields >90 % and enantiomeric ratios of โ‰ฅ90:10. Predominantly 2:1 products were obtained from the corresponding reactions with monoaryldiazoยญmethanes. The measured rate constants are in good agreement with the rate constants derived from the oneโ€bond nucleophilicity parameters N and sN of diazomethanes and the oneโ€bond electrophilicity parameters E of iminium ions as well as with quantum chemically calculated activation energies.

https://ift.tt/2xdpggW

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Research S.O.S.โ€”Ask your research and technical questions

Ask the /r/chemistry intelligentsia your research/technical questions. This is a great way to reach out to a broad chemistry network about anything you are curious about or need insight with.

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... keep reading on reddit โžก

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Methylation of biological extracts for gas chromatography.

Hello everybody,

has some a good alternative idea instead of using diazomethane for methylation prior to GC analysis? I want to do derivatizations of carboxylic acids in biological extracts. What is about TMSC/MeoH? How is the procedure when using TMSC/MeOH? Other alternatives? Acid or base catalyzed derivatization using MeOH is undesired.

Thank you!

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... keep reading on reddit โžก

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๐Ÿ“ฐ︎ r/nullthworldproblems
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๐Ÿ‘ค︎ u/stroke_bot
๐Ÿ“…︎ May 17 2019
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What are you working on? (#realtimechem)

Hello /r/chemistry.

It's everyone's favorite day of the week. Time to share (or rant about) how your research/work/studying is going and what you're working on this week.

For those that tweet: #realtimechem

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๐Ÿ“ฐ︎ r/chemistry
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๐Ÿ‘ค︎ u/AutoModerator
๐Ÿ“…︎ Sep 10 2019
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Huisgenโ€™s 1,3โ€Dipolar Cycloadditions to Fulvenes via Ambimodal [6+4]/[4+2] Transition States

Abstract: Huisgenโ€™s 1960 announcement of the concept of 1,3โ€dipolar cycloadditions was published the year before Alderโ€™s study of the reaction of diazomethane and dimethylfulvene. The diazomethane reaction was studied again in 1970 by Houk et al., and shown to give a [6+4] adduct. Padwaโ€™s nitrile ylide cycloaddition to dimethylfulvene (1978) gave [6+4] and [4+2] adducts. We have performed computational studies of these reactions with DFT and show that they involve ambimodal [6+4]/[4+2] transition states that can lead to either type of cycloadduct from one transition state. We dedicate this paper to the extraordinary life and humanity of Rolf Huisgen, and to the undying influence of his discoveries on chemistry.

https://ift.tt/2WEFUi9

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๐Ÿ“ฐ︎ r/ACIE
๐Ÿ’ฌ︎
๐Ÿ‘ค︎ u/TomisMeMyselfandI
๐Ÿ“…︎ May 09 2020
๐Ÿšจ︎ report
What are you working on? (#realtimechem)

Hello /r/chemistry.

It's everyone's favorite day of the week. Time to share (or rant about) how your research/work/studying is going and what you're working on this week.

For those that tweet: #realtimechem

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๐Ÿ“ฐ︎ r/chemistry
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๐Ÿ‘ค︎ u/AutoModerator
๐Ÿ“…︎ Mar 12 2019
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Has anyone worked with Trimethylsilyldiazomethane (TMSD) NEED HELP!

Hi,

I want to methylate the phosphate groups on a bisphosphonate moiety using TMSD for LC-MS/MS as I have read about the success in many papers and the reaction seems to be quite simple. No one in my lab group has ever used TMSD.

However, I am a first year masters student and have never worked with a chemical before that needs to be stored under nitrogen. My background is also in health sciences and not chemistry, so I am unfamiliar with some of these processes. How do I even store a chemical under nitrogen?

Now I am paranoid that if I open my vial of TMSD in air at all it will degrade or react in the air. I am also unsure if all the reaction steps need to be carried out in an inert environment? Has anyone worked with TMSD or diazomethane before?

Any help or tips is immensely appreciated!

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๐Ÿ“ฐ︎ r/labrats
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๐Ÿ‘ค︎ u/malibubandit
๐Ÿ“…︎ Nov 23 2019
๐Ÿšจ︎ report

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