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{{Redirect|Meerwein's salt||Trimethyloxonium tetrafluoroborate}} |
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{{chembox |
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{{Chembox |
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| Reference = |
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| Verifiedfields = changed |
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| Name = Triethyloxonium tetrafluoroborate |
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| Watchedfields = changed |
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| ImageFile = Triethyloxonium tetrafluoroborate.png |
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| verifiedrevid = 409427530 |
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| ImageSize = 280px |
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| ImageFileL1 = Triethyloxonium-3D-balls.png |
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| ImageFile = Triethyloxonium tetrafluoroborate.png |
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| ImageFile_Ref = {{chemboximage|correct|??}} |
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| ImageSizeL1 = 170px |
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| ImageSize = 210 |
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| ImageNameL1 = Ball-and-stick model of the triethyloxonium cation |
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| ImageAlt = Skeletal formula of triethyloxonium tetrafluoroborate |
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| ImageFileR1 = Tetrafluoroborate-ion-3D-balls.png |
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| ImageFile1 = Triethyloxonium tetrafluoroborate 3D ball.png |
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| ImageNameR1 = Ball-and-stick model of the tetrafluoroborate anion |
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| ImageFile1_Ref = {{chemboximage|correct|??}} |
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| IUPACName = Triethyloxonium tetrafluoroborate |
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| ImageSize1 = 250 |
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| Section1 = {{Chembox Identifiers |
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| ImageAltL1 = Ball and stick models of the component ions of triethyloxonium tetrafluoroborate |
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| CASNo = 368-39-8 |
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| IUPACName = Triethyloxonium tetrafluoroborate |
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| SMILES = |
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|Section1={{Chembox Identifiers |
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| RTECS = |
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| CASNo_Ref = {{cascite|correct|??}} |
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| EINECS = |
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| CASNo = 368-39-8 |
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}} |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| Section2 = {{Chembox Properties |
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| UNII = Z0B19DD36J |
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| Formula = C<sub>6</sub>H<sub>15</sub>BF<sub>4</sub>O |
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| PubChem = 2723982 |
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| MolarMass = 189,99 g/mol |
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| Density = |
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| ChemSpiderID = 2006158 |
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| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} |
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| MeltingPt = 91–92 °C |
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| BoilingPt = dec. |
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| UNNumber = 3261 |
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| FlashPt = |
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| Beilstein = 3598090 |
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| SMILES = F(F)(F)F.CC(CC)CC |
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}} |
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| StdInChI = 1S/C6H15O.BF4/c1-4-7(5-2)6-3;2-1(3,4)5/h4-6H2,1-3H3;/q+1;-1 |
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| Section7 = {{Chembox Hazards |
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| StdInChI_Ref = {{stdinchicite|changed|chemspider}} |
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| RPhrases = 34-40 |
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| StdInChIKey = IYDQMLLDOVRSJJ-UHFFFAOYSA-N |
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| SPhrases = 23-24/25-26-36/37/39-45 |
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| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} |
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}} |
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}} |
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|Section2={{Chembox Properties |
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| Formula = {{chem2|+−}} |
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| C=6 | H=15 | B=1 | F=4 | O=1 |
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| MeltingPtC = 91 to 92 |
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| Solubility = Reacts |
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}} |
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|Section3={{Chembox Hazards |
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| Hazards_ref = <ref>{{cite web |title=Triethyloxonium tetrafluoroborate |url=https://www.sigmaaldrich.com/AU/en/product/SIAL/90520 |publisher=Sigma Aldrich}}</ref> |
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| GHSPictograms = {{GHS05}} |
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| GHSSignalWord = Danger |
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| HPhrases = {{H-phrases|314}} |
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| PPhrases = {{P-phrases|260|280|303+361+353|304+340+310|305+351+338|310|363}} |
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}} |
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}} |
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'''Triethyloxonium tetrafluoroborate''' is the ] ] compound with the formula {{chem2|+−}}. It is often called '''Meerwein's reagent''' or '''Meerwein's salt''' after its discoverer ].<ref>{{cite journal | title = Über Tertiäre Oxoniumsalze, I |author1=H. Meerwein |author2=G. Hinz |author3=P. Hofmann |author4=E. Kroning |author5=E. Pfeil |name-list-style=amp | journal = Journal für Praktische Chemie| volume = 147 | issue = 10–12| pages = 257 | year = 1937| doi = 10.1002/prac.19371471001}}</ref><ref>{{cite journal | title = Über Tertiäre Oxoniumsalze, II |author1=H. Meerwein |author2=E. Bettenberg |author3=H. Gold |author4=E. Pfeil |author5=G. Willfang |name-list-style=amp | journal = Journal für Praktische Chemie| volume = 154 | issue = 3–5| pages = 83 | year = 1940| doi = 10.1002/prac.19391540305}}</ref> Also well known and commercially available is the related ]. The compounds are white solids that dissolve in polar organic solvents. They are strong ]s. Aside from the ] salt, many related derivatives are available.<ref>Hartwig Perst, Dave G. Seapy "Triethyloxonium Tetrafluoroborate" in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons, New York, 2008. {{doi|10.1002/047084289X.rt223.pub2}}. Article Online Posting Date: March 14, 2008</ref> |
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'''Triethyloxonium tetrafluoroborate''' is the ] ] compound with the formula BF<sub>4</sub>. It is often called Meerwein's reagent after its discoverer ].<ref>{{cite journal |
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| title = Über Tertiäre Oxoniumsalze, I |
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| author = H. Meerwein, G. Hinz, P. Hofmann, E. Kroning, and E. Pfeil |
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| journal = Journal für Praktische Chemie |
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| volume = 147 |
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| issue = 10-12 |
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| pages = 257 |
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| year = 1937 |
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| url = |
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| doi = 10.1002/prac.19371471001 }}{{cite journal |
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| title = Über Tertiäre Oxoniumsalze, II |
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| author = H. Meerwein, E. Bettenberg, H. Gold, E. Pfeil, and G. Willfang |
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| journal = Journal für Praktische Chemie |
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| volume = 154 |
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| issue = 3-5 |
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| pages = 83 |
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| year = 1940 |
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| url = |
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| doi = 10.1002/prac.19391540305}}</ref> Also well known and commercially available is the related ]. The compounds are exceptionally strong ]s. Aside from the BF<sub>4</sub><sup>−</sup> salt, many related derivatives are available with varying solubilities and stabilities.<ref>Hartwig Perst, Dave G. Seapy "Triethyloxonium Tetrafluoroborate" in Encyclopedia of Reagents for Organic Synthesis |
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John Wiley & Sons, New York, 2008. {{DOI|10.1002/047084289X.rt223.pub2}}. Article Online Posting Date: March 14, 2008</ref> |
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==Synthesis== |
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==Synthesis and reactivity== |
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Triethyloxonium tetrafluoroborate is prepared from ], ], and ]:<ref>{{OrgSynth | author = H. Meerwein | collvol = 5 | year = 1973| collvolpages = 1080 | prep = cv5p1080| title = Triethyloxonium fluoroborate}}</ref> |
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Triethyloxonium tetrafluoroborate is prepared from ], ], and ]:<ref>{{OrgSynth | author = H. Meerwein | volume = 46 | year = 1966| page = 113 | doi = 10.15227/orgsyn.046.0113| title = Triethyloxonium fluoroborate}}</ref> |
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:{{chem2|4 Et2O*BF3 + 2 Et2O + 3 C2H3OCH2Cl → 3 +− + B(OCH(CH2Cl)CH2OEt)3}} |
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: 4 Et<sub>2</sub>O·BF<sub>3</sub> + 2 Et<sub>2</sub>O + 3 C<sub>2</sub>H<sub>3</sub>(O)CH<sub>2</sub>Cl → 3 Et<sub>3</sub>O<sup>+</sup>BF<sub>4</sub><sup>−</sup> + B<sub>3</sub> |
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The trimethyloxonium salt is available from ] via an analogous route.<ref>{{OrgSynth | author = T. J. Curphey | collvol = 6 | year = 1988| collvolpages = 1019 | prep = CV6P1019| title = Trimethyloxonium tetrafluoroborate}}</ref> These salts do not have long shelf-lives at room temperature. These salts degrade by hydrolysis: |
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where the Et stands for ]. The trimethyloxonium salt is available from ] via an analogous route.<ref>{{OrgSynth | author = T. J. Curphey | collvol = 6 | year = 1988| collvolpages = 1019 | prep = CV6P1019| title = Trimethyloxonium tetrafluoroborate}}</ref> These salts do not have long shelf-lives at room temperature. They degrade by hydrolysis: |
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:{{chem2|+− + H2O → Et2O + EtOH + −]]}} |
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:<sup>+</sup>BF<sub>4</sub><sup>−</sup> + H<sub>2</sub>O → (CH<sub>3</sub>CH<sub>2</sub>)<sub>2</sub>O + CH<sub>3</sub>CH<sub>2</sub>OH + ] |
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The propensity of trialkyloxoniums to undergo alkyl-exchange may be utilized to the chemists' advantage. For example, trimethyloxonium tetrafluoroborate, which reacts sluggishly due to low solubility in most compatible solvents may be converted in-situ to higher alkyl/more soluble oxoniums, thereby speeding up alkylation reactions.<ref>{{cite journal | author = Vartak A.P. and Crooks P.A. | title = A Scalable Enantioselective synthesis of the alpha2-adrenergic Agonist, Lofexidine | journal = ] | year = 2009 | volume = 13 | issue = 3 | pages = 415–419 | doi = 10.1021/op8002689}}</ref> |
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The propensity of trialkyloxonium salts for alkyl-exchange can be advantageous. For example, trimethyloxonium tetrafluoroborate, which reacts sluggishly due to its low solubility in most compatible solvents, may be converted in situ to higher alkyl/more soluble oxoniums, thereby accelerating alkylation reactions.<ref>{{cite journal |author1=Vartak A.P. |author2=Crooks P.A.|name-list-style=amp | title = A Scalable Enantioselective synthesis of the alpha2-adrenergic Agonist, Lofexidine | journal = ] | year = 2009 | volume = 13 | issue = 3 | pages = 415–419 | doi = 10.1021/op8002689}}</ref> |
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This reagent is useful for esterification of carboxylic acids under conditions where acid-catalyzed reactions are infeasible: <ref>{{cite journal |
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|first1=Douglas J.|last1=Raber|first2=Patrick |last2=Gariano, Jr|first3=Albert O. |last3=Brod|first4=Anne L. |last4=Gariano|first5=Wayne C.|last5=Guida|doi=10.15227/orgsyn.056.0059 |title=Esterification of Carboxylic Acids with Trialkyloxonium Salts: Ethyl and Methyl 4-Acetoxybenzoates |journal=Organic Syntheses |date=1977 |volume=56 |page=59 }}</ref> |
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:{{chem2|RCO2H + (C2H5)3OBF4 -> RCO2C2H5 + (C2H5)2O + HBF4}} |
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==Structure== |
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==Structure== |
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The structure of triethyloxonium tetrafluoroborate has not been characterized by ], but the structure of triethyloxonium ] has been examined. The measurements confirm that the cation is pyramidal with C-O-C angles in the range 109.4°–115.5°. The average C–O distance is 1.49 Å.<ref>{{cite journal |doi=10.1021/ja00373a006|title=Structure of Oxonium Ions: An X-Ray Crystallographic Study of Triethyloxonium Hexafluorophosphate and Triphenyloxonium Tetraphenylborate|year=1982|last1=Watkins|first1=Michael I.|last2=Ip|first2=Wai Man|last3=Olah|first3=George A.|last4=Bau|first4=Robert|journal=Journal of the American Chemical Society|volume=104|issue=9|pages=2365–2372}}</ref> |
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The compound features pyramidal oxonium cation and a tetrahedral fluoroborate anion. Reflecting its ionic character, the salt dissolves in polar but inert solvents such as ], ], and ]. |
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==Safety== |
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==Safety== |
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Triethyloxonium tetrafluoroborate is a strong alkylating agent, although the hazards are diminished because it is non-volatile. It releases strong acid upon contact with water. The properties of the methyl derivative are similar. |
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Triethyloxonium tetrafluoroborate is a very strong alkylating agent, although the hazards are diminished because it is non-volatile. It releases strong acid upon contact with water. The properties of the methyl derivative are similar. |
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==Use== |
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Alkylating agent for nucleophilic functional groups in organic synthesis. |
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==References== |
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==References== |
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<references/> |
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<references/> |
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{{Tetrafluoroborates}} |
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{{chem-stub}} |
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