tag:blogger.com,1999:blog-8964719845369935777.post308986853642521334..comments2024-03-27T21:23:40.339-04:00Comments on Chemjobber: Twitter: TMS-azide explosion at University of MinnesotaChemjobberhttp://www.blogger.com/profile/15932113680515602275noreply@blogger.comBlogger36125tag:blogger.com,1999:blog-8964719845369935777.post-13745925439609416532014-11-22T14:56:13.872-05:002014-11-22T14:56:13.872-05:00Not really. Just came back from a conference and o...Not really. Just came back from a conference and one of my friends who is a PI mentioned that 1h of grad student labor costs ~$50-70, counting tuition and overhead. So, that this should happen is stupid. Inefficient, too.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-80288329148573831342014-08-08T14:31:41.504-04:002014-08-08T14:31:41.504-04:00These guys substituted PEG for diglyme which is sp...These guys substituted PEG for diglyme which is specified in the orgsyn prep. PEG stands for polyethylene glycol. As in alcohol. It's a short-chain oligomer of ethylene oxide terminated with hydroxyl groups. It is different in that way from diglyme, which is diethylene glycol dimethyl ether. Now it's obvious why hydrazoic acid was formed in this accident, whereas the orgsyn prep is safe.<br />Bruce Berrisnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-24591841219478984152014-08-07T20:53:34.390-04:002014-08-07T20:53:34.390-04:00If you want to make organic azides by a Mitsunobu ...If you want to make organic azides by a Mitsunobu procedure, try Rollin's method (Synthesis, 1990, 130) which uses the safe, stable, crystalline and easy-to-make bis-pyridine complex of zinc azide. No H+ at all! Anyone using a hazardous procedure should first consider all alternatives.Rodericknoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-79623638205321034622014-07-20T15:34:06.951-04:002014-07-20T15:34:06.951-04:00TMS-azide is often touted as "safe". Ho...TMS-azide is often touted as "safe". However, for safety analysis it should be considered the same as hydrazoic acid as there are routes beside hydrolysis by which TMS-azide can decompose to hydrazoic acid. Likely another such route was discovered here. All azide reactions should be handled with care especially when hydrazoic acid can be formed. I'm not a fan of this reagent and other chemistry should be used where possible. Otherwise use in dilute solution. <br />Tom<br />archibaldmail@gmail.com <br /> Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-7550552314464033192014-06-26T10:53:18.652-04:002014-06-26T10:53:18.652-04:00I went to grad school so I understand this mentali...I went to grad school so I understand this mentality, but damn. That hood isn't going to be cheap to repair. Rebeccanoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-1728118771925682752014-06-26T08:37:27.017-04:002014-06-26T08:37:27.017-04:00All this when it only costs $600 to buy 200g ........All this when it only costs $600 to buy 200g .....Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-35093180404591090972014-06-24T18:59:12.184-04:002014-06-24T18:59:12.184-04:00200 g preparation of TMSN3 is borderline insane in...200 g preparation of TMSN3 is borderline insane in an academic setting. Definitely some negligence on part of the PI as well as the chemist performing the task.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-85190976964751659882014-06-24T14:51:18.873-04:002014-06-24T14:51:18.873-04:00The original tweet said 200 grams. The original tweet said 200 grams. Chemjobberhttps://www.blogger.com/profile/15932113680515602275noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-7264603311765285022014-06-24T14:36:22.010-04:002014-06-24T14:36:22.010-04:00Solvents are cheap. Labor, and waste is free (to ...Solvents are cheap. Labor, and waste is free (to the PI). Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-24946951581312163502014-06-24T14:04:08.437-04:002014-06-24T14:04:08.437-04:00What scale was this on? I wonder if the injuries a...What scale was this on? I wonder if the injuries are worse than they say because that hood got wrecked.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-52892636756248669442014-06-22T09:10:00.232-04:002014-06-22T09:10:00.232-04:00If you've been to graduate school, then you kn...If you've been to graduate school, then you know that's a terrible assumption.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-81071700394997487612014-06-21T10:46:33.358-04:002014-06-21T10:46:33.358-04:00Reportedly, this student used azides all the time,...Reportedly, this student used azides all the time, so I'm guessing they were fully trained. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-43640419215868642552014-06-20T14:04:22.900-04:002014-06-20T14:04:22.900-04:00If you wanted to make a 10g batch of TMSazide, wou...If you wanted to make a 10g batch of TMSazide, would take 10g of TMSCl and 6 g of NaN3, for a cost of $9 plus labor, solvents, waste, lost time doing something better, etc. Thats about an even trade if you ask meAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-86146365569740318692014-06-20T13:51:35.114-04:002014-06-20T13:51:35.114-04:00Because TMSCl is $0.60/g and NaN3 is $0.50/g. Wh...Because TMSCl is $0.60/g and NaN3 is $0.50/g. When there is no money, grad students are forced to do what's cheap.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-26319845581563192042014-06-20T13:45:27.111-04:002014-06-20T13:45:27.111-04:00Why is anyone making this in the first place? $3 ...Why is anyone making this in the first place? $3 /g from AldrichAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-85311901541513558802014-06-19T19:51:07.726-04:002014-06-19T19:51:07.726-04:00The student who was injured in the azide reaction ...The student who was injured in the azide reaction and the student who posted it to Twitter are two different people, both at the University of Minnesota. Chemjobberhttps://www.blogger.com/profile/15932113680515602275noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-48523746439009691172014-06-19T19:49:02.454-04:002014-06-19T19:49:02.454-04:00"4. The request to remove the picture was ret..."4. The request to remove the picture was retracted by the grad student. "<br />Kudos to the grad student for wanting others to learn from this incident so soon after it happened. That takes a huge amount of emotional strength. I know, because I did not have such strength in a less severe situation. I hope you heal quickly.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-9466331816768094092014-06-19T11:26:06.779-04:002014-06-19T11:26:06.779-04:00All good choices. I am a huge fan of "Prudent...All good choices. I am a huge fan of "Prudent Practices in the Laboratory", since it is free and searchable. It also contains safe destruction procedures:<br /><br />http://www.nap.edu/openbook.php?record_id=4911<br />Chemjobberhttps://www.blogger.com/profile/15932113680515602275noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-51727205383060283722014-06-19T11:22:34.072-04:002014-06-19T11:22:34.072-04:00The MSDS provides hazards, first aide, toxicology,...The MSDS provides hazards, first aide, toxicology, recommended PPE, phys. props etc. Also keep in mind that there are a few other texts which are very useful when preparing to hande materials such as azides: “Bretherick’s Handbook of Reactive Chemical Hazards” and “Destruction of Hazardous Chemical in the Laboratory.” Always use the literature as much as possible to raise awareness and be safe.Danhttps://www.elsevier.com/books/brethericks-handbook-of-reactive-chemical-hazards/urben/978-0-12-372563-9noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-7682916765451877052014-06-19T01:19:03.941-04:002014-06-19T01:19:03.941-04:00I actually used that procedure for a couple of yea...I actually used that procedure for a couple of years with no incidents during deactivation; this was for sodium azide and some transition-metal azides. You just have to make sure you're using enough nitrite in the first place. Aarón G.https://www.blogger.com/profile/09348404403145665117noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-35901789113331542632014-06-19T00:15:26.152-04:002014-06-19T00:15:26.152-04:00So, I ask the crowd, how would you quench/dispose ...So, I ask the crowd, how would you quench/dispose TMS-azide? I have been reading about several reactions recently where a slight excess (1.2-1.5 equiv.) of TMS-azide is used but it's not apparent how the authors deal with the extra azide. <br /><br />Is something like this reasonable? <br /><br />http://www.ehs.neu.edu/hazardous_waste/fact_sheets/sodium_azide/ Swishhttps://www.blogger.com/profile/02700713781994044471noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-15857392705867729662014-06-18T23:17:55.016-04:002014-06-18T23:17:55.016-04:00I work with azoic acid. The way to generate it is ...I work with azoic acid. The way to generate it is adding slowly sulphuric acid to a mixture of toluene, water and sodium azide. The toluene solution thus formed can be later titrated and used. It is excellent for Mitsunobu reactions. Obviously it is a highly toxic and explosive and must be handled carefully. Azides per se are tricky business, but they are very good protective groups and are found ubiquitously in the chemistry literature. As chemists we must be prepared to handle any type of reactions, dangerous or not, however we must fully understand what we are doing. Accidents as the one described are a good example of what happens when someone does something that he does not fully understand. It always comes back to the same old story, document you're self before running a new reaction and be sure you understand well what are you doing. If you still have doubts, ask.Savohttps://www.blogger.com/profile/16812573441510714244noreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-56876504890895859202014-06-18T19:31:58.265-04:002014-06-18T19:31:58.265-04:00sodium azide does not detonate in airbags. It def...sodium azide does not detonate in airbags. It deflagrates. If it detonated you would be dead. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-10164697479031223992014-06-18T19:14:49.684-04:002014-06-18T19:14:49.684-04:00Solid azides are shock-sensitive. If you put a few...Solid azides are shock-sensitive. If you put a few milligrams of NaN3 on the bench top and hit it with a hammer, it would create a little spark and a pop sound. Explosions in the chemistry lab are part of the business. This is why it's important to have good safety habits and treat unknown compounds like they can kill you. I remember one time my unknown compound detonated in the flask I was holding it in my hand. It required surgery to remove the bigger shards glass. Glass still comes out of that hand from time to time. Luckily my face was protected by the hood sash. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8964719845369935777.post-86025450694625503622014-06-18T16:56:56.056-04:002014-06-18T16:56:56.056-04:00I don't know how it's initiated, though, a...I don't know how it's initiated, though, and how much energy it takes. HN3 is spontaneously explosive, and I couldn't find anything on NaN3's shock sensitivity, just its toxicity, ability to generate HN3 and other more explosive metal azides. Since it's an azide, it probably still wants to be N2, and other gorp, though.<br /><br />I was assuming that insensitive = not explosive. Perhaps it would be better to say that NaN3 doesn't easily explode (high kinetic barrier), while HN3 explodes really easily (really low kinetic barrier), as do lots of other azides.Hapnoreply@blogger.com