تثبيت النيتروجين: الفرق بين النسختين
| [نسخة منشورة] | [نسخة منشورة] |
تم حذف المحتوى تمت إضافة المحتوى
ASammourBot (نقاش | مساهمات) ط روبوت: +تصنيف:علم التربة +تنسيقات تجميلية |
ط بوت:التعريب |
||
سطر 119:
Catalytic chemical nitrogen fixation at temperatures considerably lower than the Haber process is an ongoing scientific endeavor. Nitrogen was converted to ammonia and hydrazine by [[Alexander E. Shilov]] in 1970.<ref>"Catalytic reduction of molecular nitrogen in solutions" A. E. Shilov ''Russian Chemical Bulletin'' Volume 52, Number 12, 2555–2562, {{DOI|10.1023/B:RUCB.0000019873.81002.60}}</ref><ref>"Reduction of dinitrogen" Richard R. Schrock ''PNAS'' 14 November 2006 vol. 103 no. 46 17087 {{DOI|10.1073/pnas.0603633103}}</ref>
Few compounds will cleave the N<sub>2</sub> molecule. Under an atmosphere of nitrogen, lithium metal converts to [[نتريد الليثيوم|lithium nitride]]. Treatment of the resulting nitride gives ammonia. Another example of [[تكسر متماثل|homolytic cleavage]] of dinitrogen under mild conditions was published in 1995. Two equivalents of a [[موليبدنوم|molybdenum]] complex reacted with one equivalent of dinitrogen, creating a [[
[[Trimethylsilyl chloride]], lithium, and nitrogen molecule react to give [[tris(trimethylsilyl)amine]], under catalysis by [[nichrome]] wire or [[chromium trichloride]] in tetrahydrofuran.
سطر 125:
:3 Me<sub>3</sub>SiCl + 3 Li + 1/2 N2 → (Me<sub>3</sub>Si)<sub>3</sub>N + 3 LiCl
Tris(trimethylsilyl)amine can then be used for reaction with α,δ,ω-tri[[كيتون|ketones]] to give tricyclic [[
Catalytic systems for converting nitrogen to ammonia have been developed since the 1980s.<ref>C. J. Pickett, "The Chatt Cycle and the Mechanism of Enzymic Reduction of Molecular Nitrogen", ''J. Biol. Inorg. Chem.'' 1996 1, 601–606.</ref> In 2003 another was reported based on molybdenum compound, a proton source, and a strong [[مختزل|reducing agent]].<ref>''Synthesis and Reactions of Molybdenum Triamidoamine Complexes Containing Hexaisopropylterphenyl Substituents'' Dmitry V. Yandulov, [[ريتشارد شروك|Richard R. Schrock]], Arnold L. Rheingold, Christopher Ceccarelli, and William M. Davis Inorg. Chem.; '''2003'''; 42(3) pp 796–813; (Article) {{DOI|10.1021/ic020505l}}</ref><ref>"Catalytic Reduction of Dinitrogen to Ammonia at a Single Molybdenum Center" Dmitry V. Yandulov and Richard R. Schrock ''[[ساينس|Science]]'' 4 July '''2003''': Vol. 301. no. 5629, pp. 76–78 {{DOI|10.1126/science.1085326}}</ref><ref>The catalyst is based on [[molybdenum(V) chloride]] and [[tris(2-aminoethyl)amine]] substituted with three very bulky hexa-isopropylterphenyl (HIPT) groups. Nitrogen adds end-on to the molybdenum atom, and the bulky HIPT substituents prevent the formation of the stable and nonreactive Mo-N=N-Mo [[ثنائي الوحدات|dimer]], and the nitrogen is reduced in an isolated pocket. The proton donor is a [[pyridinium]] cation, which is accompanied by a [[tetraborate]] counter ion. The [[مختزل|reducing agent]] is [[decamethylchromocene]]. All ammonia formed is collected as the HCl salt by trapping the distillate with a HCl solution</ref><ref>Note also that, although the dinitrogen complex is shown in brackets, this species can be isolated and characterized. Here the brackets do not indicate that the intermediate is not observed.</ref> However, this catalytic reduction fixates only a few nitrogen molecules.
| |||