| 词条 | 1,1-Dimethyldiborane |
| 释义 |
| Name = 1,1-Dimethyldiborane | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = | ImageFile = 1,1-dimethyldiborane.svg | ImageFile_Ref = | ImageSize = 150px | ImageName = | ImageFile1 = | ImageFile1_Ref = | ImageSize1 = | ImageName1 = | IUPACName = 1,1-Dimethyldiborane | OtherNames = Unsymmetrical dimethyldiborane |Section1={{Chembox Identifiers | CASNo1 = 16924-32-6 | CASNo1_Ref = [1] | CASNo2 = | PubChem = | ChemSpiderID = | ChemSpiderID_Ref = | EINECS = | UNNumber = | KEGG = | KEGG_Ref = | MeSHName = | ChEBI_Ref = | ChEBI = | ChEMBL = | ChEMBL_Ref = | RTECS = | Beilstein = | Gmelin = | SMILES = C[B]1(C)[H][BH2][H]1 | StdInChI = 1S/C2H10B2/c1-4(2)5-3-6-4/h3H2,1-2H3 | StdInChI_Ref = | InChI = | StdInChIKey = KEWIJCBOFAPULG-UHFFFAOYSA-N | StdInChIKey_Ref = | InChIKey = }} |Section2={{Chembox Properties | Formula = {{Chem|(|CH|3|)|2|B|2|H|4}} | MolarMass = 55.72 g mol−1 | Appearance = Colorless gas | Density = | SolubleOther = Soluble in ether, pentane, tetrahydrofuran | Solvent = organic solvents | MeltingPtC = -150.2 | BoilingPtC = -4 | VaporPressure = | Viscosity = | Odor = }} |Section3={{Chembox Structure | PointGroup = | Coordination = | MolShape = | Dipole = }} |Section4={{Chembox Thermochemistry | DeltaHf = -25 kcal/mol | Entropy = }} |Section5={{Chembox Hazards | EUClass = | RPhrases = | SPhrases = | NFPA_ref = [2] | NFPA-H = | NFPA-F = 2 | NFPA-R = 2 | IDLH = | REL = | PEL = | LC50 = | LCLo = }} |Section8={{Chembox Related | OtherFunction_label = alkyl boranes | OtherFunction = Methyldiborane Trimethyldiborane Tetramethyldiborane Trimethylborane Diethyldiborane | OtherCompounds = }} }} 1,1-Dimethyldiborane is the organoboron compound with the formula (CH3)2B(μ-H)2BH2. A pair of related 1,2-dimethyldiboranes are also known.[3] It is a colorless gas that ignites in air. FormationThe methylboranes were first prepared by H. I. Schlesinger and A. O. Walker in the 1930s.[4][5] Methylboranes are formed by the reaction of diborane and trimethylborane. This reaction produces four different substitution of methyl with hydrogen on diborane. Produced are 1-methyldiborane, 1,1-dimethyldborane, 1,1,2-trimethyldiborane, and 1,1,2,2-tetramethyldiborane.[6] Tetramethyl lead reacts with diborane in a 1,2-dimethoxyethane solvent at room temperature to make a range of methyl substituted diboranes, ending up at trimethylborane, but including 1,1-dimethyldiborane, and trimethyldiborane. The other outputs of the reaction are hydrogen gas and lead metal.[7]Other methods to form methyldiboranes include heating trimethylborane with hydrogen. Alternatively trimethylborane reacts with borohydride salts with in the presence of hydrogen chloride, aluminium chloride, or boron trichloride. If the borohydride is sodium borohydride, then methane is a side product. If the metal is lithium then no methane is produced.[4] dimethylchloroborane and methyldichloroborane are also produced as gaseous products.[4] When Cp2Zr(CH3)2 reacts with borane dissolved in tetrahydrofuran, a borohydro group inserts into the zirconium carbon bond, and methyl diboranes are produced.[8] In ether dimethylcalcium reacts with diborane to produce dimethyldiborane and calcium borohydride:[9] Ca(CH3)2 + 2B2H6 → Ca(BH4)2 + B2H4(CH3)2 1,2-dimethyldiborane slowly converts on standing to 1,1-dimethyldiborane.[10] Gas chromatography can be used to determine the amounts of the methyl boranes in a mixture. The order they elute are diborane, monomethyldiborane, trimethylborane, 1,1-dimethyldiborane, 1,2-dimethyldiborane, trimethyldiborane, and last tetramethyldiborane.[11]Selected properties1,1-Dimethyldiborane has a dipole moment of 0.87 d.[12] The predicted heat of formation for the liquid is ΔH0f=-31 kcal/mol, and for the gas -25 kcal/mol. Heat of vapourisation was measured at 5.5 kcal/mol.[13] ReactionsAt -78.5 °C methyldiborane disproportionates slowly first to diborane and 1,1-dimethyldiborane.[14] In solution methylborane is more stable against disproportionation than dimethylborane.[15] 2MeB2H5 = 1,1-Me2B2H4 + B2H6 K=2.8 Me=CH3.[16] 3[1,1-Me2B2H4] = 2 Me3B2H3 + B2H6 K=0.00027.[16] Trimethyldiborane partially disproportionates over a period of hours at room temperature to yield tetramethyldiborane and 1,2-dimethyldiborane. Over a period of weeks 1,1-dimethyldiborane appears as well.[17] Gentler oxidation of 1,1-dimethyldiborane at 80 °C yields 2,5-dimethyl-1,3,4-trioxadiboralane, a volatile liquid that contains a ring of two boron and three oxygen atoms.[18] An intermediate in this reaction is two molecules of dimethylborylhydroperoxide (CH3)2BOOH. (CAS 41557-62-5)[19] When methyldiborane is oxidised around 150 °C a similar substance methyltrioxadiboralane is produced. At the same time dimethyltrioxadiboralane and trimethylboroxine are also formed, and also hydrocarbons, diborane, hydrogen, and dimethoxyborane (dimethyl methylboronic ester).[18] References1. ^{{cite book|title=Dictionary of Organometallic Compounds|editor=Jane E. Macintyre|url=https://books.google.com.au/books?id=6F4MeeopZWQC&pg=PA468|page=468}} 2. ^{{cite book|last1=Baker|first1=Charles J.|title=The Fire Fighter's Handbook of Hazardous Materials|date=2001|publisher=Jones & Bartlett Learning|page=152|url=https://books.google.com.au/books?id=ekiWRT80VbsC&pg=PA152}} 3. ^{{cite journal|last1=Srebnik|first1=Morris|last2=Cole|first2=Thomas E.|last3=Brown|first3=Herbert C.|title=Methylborane - a remarkable unhindered monoalkylborane which achieves the controlled sequential hydroboration of representative alkenes|journal=Tetrahedron Letters|date=January 1987|volume=28|issue=33|pages=3771–3774|doi=10.1016/s0040-4039(00)96380-9}} 4. ^1 2 {{cite journal|last1=Long|first1=L. H.|last2=Wallbridge|first2=M. G. H.|title=646. The chemistry of boron. Part VI. New preparative methods and decomposition studies relating to methyldiboranes|journal=Journal of the Chemical Society (Resumed)|date=1965|pages=3513|doi=10.1039/JR9650003513|url=http://pubs.rsc.org/en/content/articlepdf/1965/jr/jr9650003513}} {{subscription required}} 5. ^{{cite journal|last1=Schlesinger|first1=H. I.|last2=Walker|first2=A. O.|title=Hydrides of Boron. IV. The Methyl Derivatives of Diborane|journal=Journal of the American Chemical Society|date=April 1935|volume=57|issue=4|pages=621–625|doi=10.1021/ja01307a009}} 6. ^{{cite journal|last1=Bell|first1=R. P.|last2=Emeléus|first2=H. J.|title=The boron hydrides and related compounds|journal=Quarterly Reviews, Chemical Society|date=1948|volume=2|issue=2|pages=132|doi=10.1039/QR9480200132}} 7. ^{{cite journal|last1=Holliday|first1=A.K.|last2=N. Jessop|first2=G.|title=The reaction of tetramethyllead with diborane|journal=Journal of Organometallic Chemistry|date=November 1967|volume=10|issue=2|pages=291–293|doi=10.1016/s0022-328x(00)93089-4}} 8. ^{{cite journal|last1=Marsella|first1=John A.|last2=Caulton|first2=Kenneth G.|title=Dealkylation of zirconium(IV) by borane: the intimate mechanism of an alkyl transfer reaction|journal=Journal of the American Chemical Society|date=May 1982|volume=104|issue=9|pages=2361–2365|doi=10.1021/ja00373a005}} 9. ^{{cite book|last1=James|first1=B. D.|last2=Wallbridge|first2=M. G. H.|editor1-last=Lippard|editor1-first=Stephen J.|title=Progress in Inorganic Chemistry, Volume 11|date=1970|publisher=Wiley|isbn=0471-54081-1|page=185|url=https://books.google.com.au/books?id=8N6nFvNzfv0C&pg=PA185|chapter=Metal Tetrahydroborates}} 10. ^{{cite journal|last1=Lehmann|first1=Walter J.|last2=Wilson|first2=Charles O.|last3=Shapiro|first3=I.|title=Infrared Spectra of Alkyldiboranes. III. 1,2-Dimethyl- and 1,2-Diethyldiboranes|journal=The Journal of Chemical Physics|date=1960|volume=33|issue=2|pages=590|doi=10.1063/1.1731190}} 11. ^{{cite journal|last1=Seely|first1=G. R.|last2=Oliver|first2=J. P.|last3=Ritter|first3=D. M.|title=Gas-Liquid Chromatographic Analysis of Mixtures Containing Methyldiboranes|journal=Analytical Chemistry|date=December 1959|volume=31|issue=12|pages=1993–1995|doi=10.1021/ac60156a032}} 12. ^{{cite journal|last1=Chiu|first1=C. W.|last2=Burg|first2=A. B.|last3=Beaudet|first3=R. A.|title=Microwave spectrum, dipole moment, barrier to internal rotation of 1,1‐dimethyldiborane|journal=The Journal of Chemical Physics|date=15 March 1983|volume=78|issue=6|pages=3562–3566|doi=10.1063/1.445182}} 13. ^{{cite web|last1=Altschuller|first1=Aubrey P.|title=Calculated Heats of Formation and Combustion of Boron Compounds (Boron, Hydrogen, Carbon, Silicon)|series=NACA Research Memorandum|url=http://naca.central.cranfield.ac.uk/reports/1955/naca-rm-e55g26.pdf|publisher=National Advisory Committee for Aeronautics|accessdate=14 August 2015|location=Cleveland, Ohio|page=22|date=4 October 1955}} 14. ^{{cite book|editor=Duward F. Shriver|last1=Bunting|first1=Roger K.|title=Inorganic Syntheses, Volume 19|date=22 Sep 2009|publisher=John Wiley and Sons|pages=237–238|url=https://books.google.com.au/books?id=Tk3HUFj9XnkC&pg=PA237|chapter=55 1-Methyldiborane|isbn=047104542X}} 15. ^{{cite journal|last1=Brown|first1=Herbert C.|last2=Cole|first2=Thomas E.|last3=Srebnik|first3=Morris|last4=Kim|first4=Kee Won|title=Hydroboration. 79. Preparation and properties of methylborane and dimethylborane and their characteristics as hydroborating agents. Synthesis of tertiary alcohols containing methyl groups via hydroboration|journal=The Journal of Organic Chemistry|date=December 1986|volume=51|issue=25|pages=4925–4930|doi=10.1021/jo00375a031}} 16. ^1 {{cite book|last1=Onak|first1=Thomas|editor1-last=Stone|editor1-first=F. G. A.|editor2-last=West|editor2-first=Robert|title=Advances in Organometallic Chemistry|date=1 January 1966|publisher=Academic Press|location=New York, London|page=284|url=https://books.google.com.au/books?id=AHEPoIx22iwC&pg=PA266|accessdate=19 August 2015|chapter=Carboranes and Organo-Substituted Boron Hydrides}} 17. ^{{cite journal|last1=Lehmann|first1=Walter J.|last2=Wilson|first2=Charles O.|last3=Shapiro|first3=I.|title=Infrared Spectra of Alkyldiboranes. V. Tri- and Tetramethyl- and Ethyldiboranes|journal=The Journal of Chemical Physics|date=1961|volume=34|issue=3|pages=783|doi=10.1063/1.1731675}} 18. ^1 {{cite journal|last1=Barton|first1=Lawrence|last2=Crump|first2=John M.|last3=Wheatley|first3=Jeffrey B.|title=Trioxadiborolanes from the oxidation of methyldiborane|journal=Journal of Organometallic Chemistry|date=June 1974|volume=72|issue=1|pages=C1–C3|doi=10.1016/s0022-328x(00)82027-6}} 19. ^{{cite journal|last1=Barton|first1=Lawrence|last2=Crump|first2=John M.|title=Oxidation of 1,1-dimethyldiborane. Gas-phase peroxide intermediates|journal=Inorganic Chemistry|date=November 1973|volume=12|issue=11|pages=2506–2510|doi=10.1021/ic50129a003}} 2 : Alkylboranes|Gases |
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