Triethyloxonium tetrafluoroborate: Difference between revisions

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			{{Redirect\|Meerwein's salt\|\|Trimethyloxonium tetrafluoroborate}}
	{{chembox
			{{Chembox
	\| Reference =
			\| Verifiedfields = changed
	\| Name = Triethyloxonium tetrafluoroborate
			\| Watchedfields = changed
	\| ImageFile = Triethyloxonium tetrafluoroborate.png
			\| verifiedrevid = 409427530
	\| ImageSize = 280px
	\| ~~ImageFileL1~~ = Triethyloxonium~~-3D-balls~~.png		\| ImageFile = Triethyloxonium tetrafluoroborate.png
			\| ImageFile_Ref = {{chemboximage\|correct\|??}}
	\| ImageSizeL1 = 170px
			\| ImageSize = 210
	\| ImageNameL1 = Ball-and-stick model of the triethyloxonium cation
			\| ImageAlt = Skeletal formula of triethyloxonium tetrafluoroborate
	\| ImageFileR1 = Tetrafluoroborate-ion-3D-balls.png
			\| ImageFile1 = Triethyloxonium tetrafluoroborate 3D ball.png
	\| ImageNameR1 = Ball-and-stick model of the tetrafluoroborate anion
			\| ImageFile1_Ref = {{chemboximage\|correct\|??}}
	\| IUPACName = Triethyloxonium tetrafluoroborate
			\| ImageSize1 = 250
	\| Section1 = {{Chembox Identifiers
			\| ImageAltL1 = Ball and stick models of the component ions of triethyloxonium tetrafluoroborate
	\| CASNo = 368-39-8
			\| IUPACName = Triethyloxonium tetrafluoroborate
	\| SMILES =
			\|Section1={{Chembox Identifiers
	\| RTECS =
			\| CASNo_Ref = {{cascite\|correct\|??}}
	\| EINECS =
			\| CASNo = 368-39-8
	}}
			\| UNII_Ref = {{fdacite\|correct\|FDA}}
	\| Section2 = {{Chembox Properties
			\| UNII = Z0B19DD36J
	\| Formula = C<sub>6</sub>H<sub>15</sub>BF<sub>4</sub>O
			\| PubChem = 2723982
	\| MolarMass = 189,99 g/mol
	\| ~~Density~~ =		\| ChemSpiderID = 2006158
			\| ChemSpiderID_Ref = {{chemspidercite\|changed\|chemspider}}
	\| MeltingPt = 91–92 °C
	\| ~~BoilingPt~~ = ~~dec.~~		\| UNNumber = 3261
	\| ~~FlashPt~~ =		\| Beilstein = 3598090
			\| SMILES = F(F)(F)F.CC(CC)CC
	}}
			\| StdInChI = 1S/C6H15O.BF4/c1-4-7(5-2)6-3;2-1(3,4)5/h4-6H2,1-3H3;/q+1;-1
	\| Section7 = {{Chembox Hazards
			\| StdInChI_Ref = {{stdinchicite\|changed\|chemspider}}
	\| RPhrases = 34-40
			\| StdInChIKey = IYDQMLLDOVRSJJ-UHFFFAOYSA-N
	\| SPhrases = 23-24/25-26-36/37/39-45
			\| StdInChIKey_Ref = {{stdinchicite\|changed\|chemspider}}
	}}
			}}
			\|Section2={{Chembox Properties
			\| Formula = {{chem2\|+−}}
			\| C=6 \| H=15 \| B=1 \| F=4 \| O=1
			\| MeltingPtC = 91 to 92
			\| Solubility = Reacts
			}}
			\|Section3={{Chembox Hazards
			\| Hazards_ref = <ref>{{cite web \|title=Triethyloxonium tetrafluoroborate \|url=https://www.sigmaaldrich.com/AU/en/product/SIAL/90520 \|publisher=Sigma Aldrich}}</ref>
			\| GHSPictograms = {{GHS05}}
			\| GHSSignalWord = Danger
			\| HPhrases = {{H-phrases\|314}}
			\| PPhrases = {{P-phrases\|260\|280\|303+361+353\|304+340+310\|305+351+338\|310\|363}}
			}}
	}}		}}

			'''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>
	'''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
	\| title = Über Tertiäre Oxoniumsalze, I
	\| author = H. Meerwein, G. Hinz, P. Hofmann, E. Kroning, and E. Pfeil
	\| journal = Journal für Praktische Chemie
	\| volume = 147
	\| issue = 10-12
	\| pages = 257
	\| year = 1937
	\| url =
	\| doi = 10.1002/prac.19371471001 }}{{cite journal
	\| title = Über Tertiäre Oxoniumsalze, II
	\| author = H. Meerwein, E. Bettenberg, H. Gold, E. Pfeil, and G. Willfang
	\| journal = Journal für Praktische Chemie
	\| volume = 154
	\| issue = 3-5
	\| pages = 83
	\| year = 1940
	\| url =
	\| 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
	John Wiley & Sons, New York, 2008. {{DOI\|10.1002/047084289X.rt223.pub2}}. Article Online Posting Date: March 14, 2008</ref>

	==Synthesis==		==Synthesis and reactivity==
	Triethyloxonium tetrafluoroborate is prepared from ], ], and ]:<ref>{{OrgSynth \| author = H. Meerwein \| ~~collvol~~ = 5 \| year = ~~1973~~\| ~~collvolpages~~ = ~~1080~~ \| ~~prep~~ = ~~cv5p1080~~\| title = Triethyloxonium fluoroborate}}</ref>		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>

			:{{chem2\|4 Et2O*BF3 + 2 Et2O + 3 C2H3OCH2Cl → 3 +− + B(OCH(CH2Cl)CH2OEt)3}}
	: 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>

	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:		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:
			:{{chem2\|+− + H2O → Et2O + EtOH + −]]}}
	:<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 + ]

	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>		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>

			This reagent is useful for esterification of carboxylic acids under conditions where acid-catalyzed reactions are infeasible: <ref>{{cite journal
			\|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>
			:{{chem2\|RCO2H + (C2H5)3OBF4 -> RCO2C2H5 + (C2H5)2O + HBF4}}

	==Structure==		==Structure==
			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>
	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 ].

	==Safety==		==Safety==
	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.		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.

	==Use==
	Alkylating agent for nucleophilic functional groups in organic synthesis.

	==References==		==References==
	<references/>		<references/>

			{{Tetrafluoroborates}}

	]		]
	]		]
	]		]
			]

	{{chem-stub}}

	]
	]

Latest revision as of 23:35, 26 July 2024

"Meerwein's salt" redirects here. For other uses, see Trimethyloxonium tetrafluoroborate.

Triethyloxonium tetrafluoroborate
Names


IUPAC name Triethyloxonium tetrafluoroborate
Identifiers
CAS Number	368-39-8
3D model (JSmol)	Interactive image
Beilstein Reference	3598090
ChemSpider	2006158
ECHA InfoCard	100.006.096
PubChem CID	2723982
UNII	Z0B19DD36J
UN number	3261
CompTox Dashboard (EPA)	DTXSID20883372
InChI InChI=1S/C6H15O.BF4/c1-4-7(5-2)6-3;2-1(3,4)5/h4-6H2,1-3H3;/q+1;-1Key: IYDQMLLDOVRSJJ-UHFFFAOYSA-N
SMILES F(F)(F)F.CC(CC)CC
Properties
Chemical formula	[(CH₃CH₂)₃O][BF₄]
Molar mass	189.99 g·mol
Melting point	91 to 92 °C (196 to 198 °F; 364 to 365 K)
Solubility in water	Reacts
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P280, P303+P361+P353, P304+P340+P310, P305+P351+P338, P310, P363
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is ?) Infobox references

Chemical compound

Triethyloxonium tetrafluoroborate is the organic oxonium compound with the formula [(CH₃CH₂)₃O][BF₄]. It is often called Meerwein's reagent or Meerwein's salt after its discoverer Hans Meerwein. Also well known and commercially available is the related trimethyloxonium tetrafluoroborate. The compounds are white solids that dissolve in polar organic solvents. They are strong alkylating agents. Aside from the BF−4 salt, many related derivatives are available.

Synthesis and reactivity

Triethyloxonium tetrafluoroborate is prepared from boron trifluoride, diethyl ether, and epichlorohydrin:

4 Et₂O·BF₃ + 2 Et₂O + 3 C₂H₃OCH₂Cl → 3 [Et₃O][BF₄] + B(OCH(CH₂Cl)CH₂OEt)₃

where the Et stands for ethyl. The trimethyloxonium salt is available from dimethyl ether via an analogous route. These salts do not have long shelf-lives at room temperature. They degrade by hydrolysis:

[Et₃O][BF₄] + H₂O → Et₂O + EtOH + H[BF₄]

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.

This reagent is useful for esterification of carboxylic acids under conditions where acid-catalyzed reactions are infeasible:

RCO₂H + (C₂H₅)₃OBF₄ → RCO₂C₂H₅ + (C₂H₅)₂O + HBF₄

Structure

The structure of triethyloxonium tetrafluoroborate has not been characterized by X-ray crystallography, but the structure of triethyloxonium hexafluorophosphate 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.

Safety

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.

References

"Triethyloxonium tetrafluoroborate". Sigma Aldrich.
H. Meerwein; G. Hinz; P. Hofmann; E. Kroning & E. Pfeil (1937). "Über Tertiäre Oxoniumsalze, I". Journal für Praktische Chemie. 147 (10–12): 257. doi:10.1002/prac.19371471001.
H. Meerwein; E. Bettenberg; H. Gold; E. Pfeil & G. Willfang (1940). "Über Tertiäre Oxoniumsalze, II". Journal für Praktische Chemie. 154 (3–5): 83. doi:10.1002/prac.19391540305.
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
H. Meerwein (1966). "Triethyloxonium fluoroborate". Organic Syntheses. 46: 113. doi:10.15227/orgsyn.046.0113.
T. J. Curphey (1988). "Trimethyloxonium tetrafluoroborate". Organic Syntheses; Collected Volumes, vol. 6, p. 1019.
Vartak A.P. & Crooks P.A. (2009). "A Scalable Enantioselective synthesis of the alpha2-adrenergic Agonist, Lofexidine". Org. Process Res. Dev. 13 (3): 415–419. doi:10.1021/op8002689.
Raber, Douglas J.; Gariano, Jr, Patrick; Brod, Albert O.; Gariano, Anne L.; Guida, Wayne C. (1977). "Esterification of Carboxylic Acids with Trialkyloxonium Salts: Ethyl and Methyl 4-Acetoxybenzoates". Organic Syntheses. 56: 59. doi:10.15227/orgsyn.056.0059.
Watkins, Michael I.; Ip, Wai Man; Olah, George A.; Bau, Robert (1982). "Structure of Oxonium Ions: An X-Ray Crystallographic Study of Triethyloxonium Hexafluorophosphate and Triphenyloxonium Tetraphenylborate". Journal of the American Chemical Society. 104 (9): 2365–2372. doi:10.1021/ja00373a006.