Cyclopentadiene is an organic compound with the formula C5H6. This colorless liquid has a unpleasant odor. At room temperature, this cyclic diene dimerizes over the course of hours to give dicyclopentadiene via a Diels–Alder reaction; this dimer can be restored by heating to give the monomer. The compound is used for the production of cyclopentene and its derivatives, it is popularly used as a precursor to the cyclopentadienyl ligand in cyclopentadienyl complexes in organometallic chemistry. Cyclopentadiene production is not distinguished from dicyclopentadiene since they are interconverted, they are obtained by steam cracking of naphtha. To obtain cyclopentadiene monomer, commercial dicyclopentadiene is cracked by heating to ~ 180 °C; the monomer is collected by distillation, used soon thereafter. The hydrogen atoms in cyclopentadiene undergo rapid -sigmatropic shifts as indicated by 1H NMR spectra recorded at various temperatures. More fluxional are the derivatives C5H5E3, wherein the heavier element migrates from carbon to carbon with a low activation barrier.
Cyclopentadiene is a reactive diene in the Diels–Alder reaction because minimal distortion of the diene is required to achieve the envelope geometry of the transition state compared to other dienes. Famously, cyclopentadiene dimerizes; the conversion occurs in hours at room temperature, but the monomer can be stored for days at −20 °C. The compound is unusually acidic for a hydrocarbon, a fact explained by the high stability of the aromatic cyclopentadienyl anion, C5H−5. Deprotonation can be achieved with a variety of bases sodium hydride, sodium metal, butyl lithium. Salts of this anion are commercially available, including sodium cyclopentadienide and lithium cyclopentadienide, they are used to prepare cyclopentadienyl complexes. Metallocenes and related cyclopentadienyl derivatives have been investigated and represent a cornerstone of organometallic chemistry owing to their high stability; the first metallocene characterised, was prepared the way many other metallocenes are prepared: by combining alkali metal derivatives of the form MC5H5 with dihalides of the transition metals: As typical example, nickelocene forms upon treating nickel chloride with sodium cyclopentadienide in THF.
NiCl2 + 2 NaC5H5 → Ni2 + 2 NaClOrganometallic complexes that include both the cyclopentadienyl anion and cyclopentadiene itself are known, one example of, the rhodocene derivative produced from the rhodocene monomer in protic solvents. It was the starting material in Leo Paquette's 1982 synthesis of dodecahedrane; the first step involved reductive dimerization of the molecule to give dihydrofulvalene, not simple addition to give dicyclopentadiene. Aside from serving as a precursor to cyclopentadienyl-based catalysts, the main commercial application of cyclopentadiene is as a precursor to comonomers. Semi-hydrogenation gives cyclopentene. Diels-Alder reaction with butadiene gives ethylidene norbornene, a comonomer in the production of EPDM rubbers; the used abbreviation of the cyclopentadienyl anion is Cp. The abbreviation played a part in the naming of copernicium: the original proposal for the element's symbol was Cp, but because of the abbreviation for this anion and the fact that lutetium was named cassiopeium and had Cp for the symbol as well, the symbol for copernicium was changed to Cn.
Aromaticity Methylcyclopentadiene, pentamethylcyclopentadiene and pentacyanocyclopentadiene found as ligands in organometallic chemistry Cyclopentadienone International Chemical Safety Card 0857 NIOSH Pocket Guide to Chemical Hazards
Armenia will participate in the Eurovision Song Contest 2020. The Armenian broadcaster Public Television company of Armenia organised a national final in order to select the Armenian entry for the 2020 contest in Rotterdam, Netherlands. Prior to the 2019 Contest, Armenia had participated in the Eurovision Song Contest thirteen times since its first entry in 2006. Armenia's highest placing in the contest, to this point, has been fourth place, which the nation achieved on two occasions: in 2008 with the song "Qélé, Qélé" performed by Sirusho and in 2014 with the song "Not Alone" performed by Aram Mp3. Armenia had, to this point, failed to qualify to the final on three occasions in 2011, 2018 and 2019; the nation withdrew from the contest in 2012 due to long-standing tensions with host country Azerbaijan. Depi Evratesil is the national final organised by AMPTV to select the artist and song that will represent Armenia in the Eurovision Song Contest 2020. Artists and composers were able to submit their entries to the broadcaster between 5 November 2019 and 31 December 2019.
From all 53 songs submitted to AMPTV, a jury panel selected 12 songs for the competition, with the selected entrants being announced on 28 January 2020. The selection jury consisted of Naira Gurjinyan, Anita Hakhverdyan, Lilia Nikoyan, Ruben Babayan, Vardan Hakobyan, Tigran Danielyan, David Tserunyan, Karen Tataryan and Anush Ter-Ghukasyan; the competing songs were released on 5 February 2020. The final took place on 15 February 2020. Twelve songs competed with the winner decided upon by the combination of the votes from three voting groups: an international jury, an Armenian jury and televoting. According to Eurovision rules, all nations with the exceptions of the host country and the "Big 5" are required to qualify from one of two semi-finals in order to compete for the final; the European Broadcasting Union split up the competing countries into six different pots based on voting patterns from previous contests, with countries with favourable voting histories put into the same pot. On 28 January 2020, a special allocation draw was held which placed each country into one of the two semi-finals, as well as which half of the show they would perform in.
Armenia was placed into the second semi-final, to be held on 14 May 2020, was scheduled to perform in the second half of the show
Simon Davies is a British lawyer and businessman. He was appointed as the youngest firmwide managing partner at Linklaters in 2008. In 2016, he moved to Lloyds Banking Group to become the chief people and strategy officer and a member of the group's executive committee. Davies joined Linklaters as a trainee in their London office in 1990 and became partner in 1999, he spent 12 years in Asia, specialising in M&A and Securities advice serving terms in each of Hong Kong and Tokyo. Davies was Managing Partner for Asia from 2003 to 2007, he was appointed as Firmwide Managing Partner in February 2007 and took up the role in January 2008. At the age of 39, he was the youngest person to hold this position. In this role, he was a member of the firm's Partnership Board, he was replaced by Linklaters former global banking head, Gideon Moore. Davies is recognised for launching the Linklaters Law and Business School in 2007, which delivers integrated business and technical skills training, he is credited for a marked improvement in the number of top-tier rankings across the firm's practice areas and strong financial performance under his leadership.
Davies has overseen a growth in the firm's geographic coverage in Asia and Africa, the development of its contentious and regulatory capabilities. Davies has led efforts to reposition Linklaters as a more progressive and diverse business, with the firm launching a global diversity action plan during his tenure as Firmwide Managing Partner; this has included introducing the target to have at least 30% females on the firm's Partnership Board and Executive Committee by 2018, for at least 30% of all new partners to be women. In recognition of its diversity efforts, Linklaters was the first organisation in the UK to be awarded the UK National Equality Standard. Davies is a member of TheCityUK / CBBC China Market Advisory Group, is involved with fostering relations between China and the UK. In 2013, Davies received from the Chinese Ambassador to the UK a fellowship of the 48 Group Club, an independent business network committed to promoting positive China-UK relations. Davies is trustee of the National Youth Theatre of Great Britain.
Davies was educated at Cambridge University. Davies is a Solicitor of the High Court of the Hong Kong Special Administrative Region, a member of The Dai-ichi Tokyo Bar Association and a Solicitor of the Senior Courts of England and Wales