The last 26th of February we had the pleasure to host the National Schools’ Analyst Competition Regional Heat at our Chemistry Teaching Labs at the School of Chemical and Biological Sciences. 13 teams were competing for a place in the final.
This national competition is for students studying AS level Chemistry or equivalent (ie Year 12). Teams comprise three students (with an accompanying teacher).
Regional heats are administered by the Analytical Division of the Royal Society of Chemistry, and take place in early spring each year. A National Final consisting of 18 to 20 teams takes place in June each year.
First, Second and Third placed teams in the National Final receive prizes of £1000, £600 and £300 plus individual prizes for students taking part.
Find out more and apply at Analytical division schools’ competition.
On Saturday 13th of February we had an open day at the chemistry department of Queen Mary University of London. Future chemistry students had the opportunity to have a chat with staff and enjoy a taste of chemistry at our teaching labs.
Dr. Tippu Sheriff, one of our lecturers, gave a great exhibition of chemistry concepts to our visitors. Students could learn about the acidic properties of CO2 in an aqueous solution. Using bromothymol blue, students can appreciate the color change from blue to yellow when the concentration of CO2 increases making the solution more acidic.
Dr. Tippu Sheriff also showed some “chemistry tricks” with liquid nitrogen. Here you are a sneak peek of what you can see when you come to visit us next time
During the next two weeks our students are doing at our Teaching Labs one of the classic reactions in Organic Chemistry, the Diels-Alder reaction. So I had some fun distilling cyclopentadiene from dicyclopentadoene for more than 100 students.
I’m including a protocol to obtain ~150 mL (2-3 horas of distillation)
The reaction apparatus is assembled by attaching a thermometer, Vigreaux distilling column and a long Liebig condenser to a 500 mL two necked flask. The receiver is cooled with an ice-water bath (00C) . Dicyclopentadiene (~250 mL) is placed in the two necked flask and heated to about 160°C with an electric heating mantle or oil bath. Thermal decomposition begins at about 150°C and distillates at 38 ~ 46°C can be obtained . Heating is applied slowly, because rapid temperature increases cause dicyclopentadiene to distill prior to undergoing thermal decomposition. In such a case, re-distillation allows narrow boiling-point distillates. Distillation took around 3 hours.The cyclopentadiene was collected at 00C and was stored at -200C for at least one week.
Cyclopentadiene dimerizes rapidly at room temperature and should be used immediately.
This is already a bit old but I loved the idea of starting the new section with the picture of our #Chemistree
We needed some Christmas spirit at our Teaching Labs
At the end of 2015 I wrote a post (Must read papers 2015) including my favourite paper of the year and recommendations of a few nice reviews/highlights to read during Christmas. During 2015 I selected several papers I wanted to write about in the blog but unfortunately I have less time than I would like and I couldn’t write a line about many of them. Now 2015 is gone and I already have a few nice papers selected this year to comment in the blog. So all these nice papers are piling up and haunt me in my dreams because I don’t have enough time (or maybe because I’m just lazy).
To make a long story short I have decided to write a follow-up post of the Must read papers 2015 to comment a little bit on the best papers I selected during 2015 that for one reason or the other attracted my attention (click on the pictures if you want to go to the paper’s websites).
The first two papers of the post fit perfectly in the section Cool Synthesis under the topic Impossible Molecules. The Impossible Molecules topic is dedicated to molecules with exotic structures, elusive molecules and synthetically challenging molecules in general. The first paper describes the first example of an amazing corannulene derivative bearing an internal heteroatom. The second paper describes a creative strategy to stabilise long cumulenes with a phenanthroline-based macrocycle.
If you have ever read this blog before, you already know I’m a bit (just a bit) obsessed with halogenating reactions so you will find several posts on the topic. There are 2 papers I couldn’t write about during 2015 that I want to highlight. The first one describes a one-pot vicinal fluorination-iodination of arynes using the diphenyliodonium salt as a catalyst and CsF as a fluorine source. The second paper describes the synthesis of the molecules Halomon, Plocamenone and Isoplocamenone using a dihalogenating reaction I wrote about in a previous post.
Another of my obsessions is the chemistry of Frustrated Lewis Pairs (FLP), and just as I said in one of my previous posts “This is not the first time and probably will not be the last time I post about Frustrated Lewis Pairs”. One of the papers I didn’t have time to write about is this nice contribution by Stephan’s group on the catalytic hydrogenation and reductive deoxygenation of ketones and aldehydes.
The next paper is another creative contribution by Alcarazo and coworkers. The paper describes an interesting alternative to hipervalent iodine species, Dihalo(imidazolium)sulfuranes that are versatile electrophilic group-transfers reagents.
The last paper I want to mention in this post caught my attention because of the interesting fact that the selectivity of the two products obtained in a copper-catalysed arylation is controlled by the choice of the reaction vessel.
Lorne Malvo, a young and ambitious postdoc, joins the lab of rising star Dr. Lou Solverson at the University of Luverne in Minnesota. Within Dr Solverson’s group, Lorne starts an industrially funded project on the Haber-Bosch process toward the artificial nitrogen fixation for the production of ammonia. The Haber-Bosch process is typically conducted at 150–250 bar and between 400–500 °C but recently in 1985 it was published a patent using a new family of iron catalysts that, according to the patent, were capable to substantially reduce the ranges of pressure and temperature with no loss of efficiency. The sponsors of the project wanted Dr Solverson and Lorne to investigate the validity of the results published in the patent and further investigate new catalysts to improve the Haber-Bosh process.
The results published in the patent lacked lots of information related to the synthesis and characterization of the catalysts used, experimental procedures and catalysis conditions were poorly described. So the initial step of reproducing published results turned into a big challenge.
LUVERNE, MINNESOTA, SEPTEMBER 1987
After more than one year of tests and catalyst screening Lorne and Dr. Solverson were not capable to reproduce the results published in the patent and started to question its veracity. Still all this work was very useful to learn about all the difficulties of the process itself and produced enough relevant data for a publication. Solverson and Malvo were aware of the difficulty of publishing a paper based on someone else’s results but also assumed the responsibility of sharing with the catalysis community their results which questioned an accepted patent. Under the title “Reinvestigation of new iron catalysts for the Haber-Bosch process” Solverson and Malvo submitted a paper to the journal Catalysis & Chemistry (from the Editorial Fargo) with an impact factor of 5.04.
LUVERNE, MINNESOTA, OCTOBER 1987
Solverson and Malvo received comments from the referees:
-Referee one considered the paper could be published in Catalysis & Chemistry because of the interest to the catalysis community and wanted to include a few more references (probably this referee’s work)
-Referee two did not accept the paper arguing that Malvo and Solverson’s contribution was only a reproduction of the work published in the patent.
Referee two was what Malvo and Solverson were most afraid of, someone that did not understand the aim of the paper which was a warning to the community about a patent that at first seemed promising. After a few unsuccessful attempts to convince referee two, Malvo and Solverson decided to submit their work to the journal Chemistry of Catalysis (Bo Munk Editorial) with an impact factor of 4.7.
LUVERNE, MINNESOTA, DECEMBER 1987
Malvo and Solverson’s paper was accepted with minor revisions in Chemistry of Catalysis. A few days before the paper was in press Malvo realised that impact factors had changed and now Chemistry of Catalysis had an impact factor of 5.426 (Previously 4.7) and Catalysis & Chemistry had an impact factor of 4.556 (Previously 5.04).
SOME YEARS AFTER THAT…
Dr Solverson was awarded with a prestigious grant and was promoted to Full Professor, he continues producing high quality research but the events occurred during 1987 made him very sceptical about the peer-review system.
Lorne Malvo could not take it anymore and lost all faith in the peer-review system, he quitted science and currently survives as soldier of fortune. If you have a problem, if no one else can help, and if you can find him, maybe you can hire him.
A couple of interesting papers on the Haber-Bosh process:
–Lessons learned and lessons to be learned for developing homogeneous transition metal complexes catalyzed reduction of N2 to ammonia. Chinnappan Sivasankar, Sambath Baskaran, Masilamani Tamizmani, Kankanala Ramakrishna. Journal of Organometallic Chemistry, Volume 752, 2014, Pages 44–58.
–Exploring the limits: A low-pressure, low-temperature Haber–Bosch process. Aleksandra Vojvodica, Andrew James Medfordb, Felix Studta, Frank Abild-Pedersena, Tuhin Suvra Khana, T. Bligaarda, J.K. Nørskov. Chemical Physics Letters, Volume 598, 2014, Pages 108–112.
To understand better this post you may want to take a look to these links:
Now that 2015 is ending I remember a nice tradition we used to have in the research centre where I did my first postdoc. At the end of December we had a “Reaction of the year” seminar in which everyone of us had to present a paper we thought it was the most important contribution of the year.
I would like to use a similar idea in this post to open a discussion in which everyone can say their #favouritepaperof2015 and why. So I am going first…
Yeah, the main reason I liked so much this paper is that I may have a bit of an obsession with halogenation reactions in general. Anyway it is a must read paper in this year 2015, I’ve recently wrote a post about it if you are interested.
Besides my favourite paper of the year, for those who want to read a bit of chemistry during the Christmas break I would like to recommend you a couple of reviews and highlights on topics I really like and I hope you also enjoy (click on the pictures to go to the links).
I’ve seen very recently a nice review on the Conia-ene reaction by Dieter Enders and co-workers and I couldn’t avoid feeling some nostalgia. A very important part of my PhD project was related to the Conia-ene reaction so today I felt like wanting to write a few lines in a post…
The Conia-ene reaction was, at its origins, a thermal cyclization reaction of unsaturated carbonyl compounds usually in an exo mode. An intramolecular cousin of the Ene Reaction. This reaction usually required temperatures in excess of 300 oC limiting its utility in the synthesis of complex molecules.
The potential of the Conia-ene reaction attracted the interest of many groups on the development of milder variants. We can find very encouraging contributions in the literature of Conia-ene reactions catalysed at much lower temperatures by Mo, Sn, Ti, Pd, Hg or Co, however these reactions usually required hard conditions in the presence of acid, bases, photochemical activation and were limited to the exo cyclization mode.
It wasn’t until the seminal works of Toste’s group using the catalytic system AuPPh3Cl/ AgOTf that we can find a general method at room temperature that can lead to both endo and exo cyclization modes.
It seems natural that the next step in the study of a reaction is an enantioselective variant. Toste and co-workers, always one step ahead, developed in 2005 the first asymmetric version of the Conia-ene reaction. The strategy: Electrophilic activation of the acetylenic moiety of b-Ketoesters with a DTBM-SEGPHOS Palladium complex as chiral promoter in the presence of the Lewis acid Yb(OTf)3.
A different approach is the generation of a chiral enolate. Dixon and co-workers used this strategy in their work by combining Cu(OTf)2 with a Brønsted base.
The Conia-ene reaction has proved to be a very useful synthetic tool toward the synthesis of cyclopentanoid products. Just to name one example (of many), Toste’s group application to the synthesis of (+)-Lycopladine A.
Do you want to know more? Take a look to these papers:
The review of the nostalgia:
– Catalytic Conia-ene and related reactions. Daniel Hack, Marcus Blümel, Pankaj Chauhan, Arne R. Philipps and Dieter Enders, Chem. Soc. Rev., 2015,44, 6059-6093
Where it all begun:
– The Thermal Cyclisation of Unsaturated Carbonyl Compounds. J. M. Conia, P. Le Perchec, Synthesis 1975, 1 – 19
Seminal works in gold catalysis
–Gold(I)-Catalyzed 5-endo-dig Carbocyclization of Acetylenic Dicarbonyl Compounds. Steven T. Staben, Joshua J. Kennedy-Smith andF. Dean Toste, Angew. Chem. Int. Ed. 2004, 43, 5350 –5352.
– Gold(I)-Catalyzed Conia-Ene Reaction of β-Ketoesters with Alkynes. Joshua J. Kennedy-Smith , Steven T. Staben , and F. Dean Toste, J. Am. Chem. Soc., 2004, 126, 4526–4527.
–Catalytic Enantioselective Conia-Ene Reaction. Britton K. Corkey and F. Dean Toste, J. Am. Chem. Soc., 2005, 127,17168–17169.
– Brønsted Base/Lewis Acid Cooperative Catalysis in the Enantioselective Conia-Ene Reaction. Ting Yang, Alessandro Ferrali, Filippo Sladojevich, Leonie Campbell and Darren J. Dixon. J. Am. Chem. Soc., 2009, 131 (26), 9140–9141.
And a bonus track, one application in synthesis
– Gold(I)-Catalyzed Cyclizations of Silyl Enol Ethers: Application to the Synthesis of (+)-Lycopladine A. Steven T. Staben, Joshua J. Kennedy-Smith, David Huang, Britton K. Corkey, Rebecca L. LaLonde andF. Dean Toste. Angew. Chem., Int. Ed., 2006,45, 5991.