N , N , N ', N ' -tetramethylformamidinium chloride

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Structural formula
Structural formula of N, N, N ′, N′-tetramethylformamidinium chloride
General
Surname N , N , N ', N ' -tetramethylformamidinium chloride
other names
  • (Dimethylaminomethylene) dimethylammonium chloride
  • Bis (dimethylamino) carbenium chloride
Molecular formula C 5 H 13 ClN 2
Brief description

Light yellow crystalline solid

External identifiers / databases
CAS number 1071-38-1
EC number 626-961-1
ECHA InfoCard 100.155.312
PubChem 9793790
Wikidata Q28504204
properties
Molar mass 136.62 g mol −1
Physical state

firmly

Melting point
  • 130-139 ° C
  • 142-144 ° C
  • 146-147 ° C
solubility

soluble in water, in acetonitrile and N , N -dimethylformamide

safety instructions
GHS labeling of hazardous substances
07 - Warning

Caution

H and P phrases H: 315-319-335
P: 261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

N , N , N ', N ' -Tetramethylformamidiniumchlorid is the simplest representative of quaternary formamidinium cations of the general formula [R 2 N-CH = NR 2 ] + with chloride as counterion , in which all the hydrogen atoms of the protonated amidine formamidine [HC (= NH 2 ) NH 2 ] + are replaced by methyl groups .

Deprotonation produces the extremely basic carbene bis (dimethylamino) carbene of the formula R 2 N-C: -NR 2 .

Occurrence and representation

N , N , N ', N ' -Tetramethylformamidinium chloride is formed in the reaction of dimethylformamide (DMF) with dimethylcarbamoyl chloride in very high yield (95%),

Synthesis of N, N, N ', N'-tetramethylformamidinium chloride from dimethylcarbamoyl chloride

The conversion of DMF with thionyl chloride in a ratio of 3: 1 provides a significantly lower yield of 72%, but a more realistic yield in view of the difficult handling of the chloride salt .

Synthesis of N, N, N ′, N′-tetramethylformamidinium chloride with thionyl chloride

properties

N , N , N ', N ' -Tetramethylformamidinium chloride is a light yellow, strongly hygroscopic solid.

For drying, the salt is dissolved in dichloromethane and solid anhydrous sodium sulfate is added to the solution . After dissolving it several times in dichloromethane / acetone and precipitating with tetrahydrofuran , a colorless solid is obtained which is stable in the absence of air and moisture.

The assumption of a mesomeric equilibrium between ionic formamidinium chloride and covalent bis (dimethylamino) chloromethane structure

Mesomerism of N, N, N ′, N′-tetramethylformamidinium chloride

a decision was made in favor of the presence of N , N , N ', N ' -tetramethylformamidinium chloride by reacting with germanium (II) chloride or tin (II) chloride .

Reaction of N, N, N ′, N′-tetramethylformamidinium chloride reaction with GeCl2

The extreme hygroscopicity of the chloride salt complicates the handling of the compound considerably. Therefore, syntheses of the much more manageable salts N , N , N ', N ' -tetramethylformamidinium methyl sulfate from the dimethylformamide-dimethyl sulfate complex and of N , N , N ', N ' -tetramethylformamidinium p-toluenesulfonate from DMF and p -Toluenesulfonic acid chloride described.

Applications

N , N , N ', N ' -Tetramethylformamidinium chloride is a suitable reagent for aminomethylenation; H. for the introduction of a = CH-NR 1 R 2 function on CH-acidic compounds. For example, ethyl cyanoacetate reacts with the formamidinium salt in the presence of solid sodium hydroxide, practically quantitatively, to form ethyl (dimethylaminomethylene) cyanoacetate.

Aminomethylenation with N, N, N ', N'-tetramethylformamidinium chloride

The aminomethylenation provides intermediates for the synthesis of heterocycles , such as. B. indoles , pyrimidines , pyridines and quinolones .

From N , N , N ', N ' -Tetramethylformamidiniumchlorid is formed with alkali metal dimethylamides, such as. B. lithium dimethylamide or sodium dimethylamide tris (dimethylamino) methane in yields of 55-84%.

Synthesis of trisdimethylaminomethane TDAM

The reaction product is also useful as a reagent for formylation and aminomethylenation.

From N , N , N ', N ' tetramethylformamidinium chloride and sodium ethylate in ethanol , dimethylformamide diethylacetal is formed in 68% yield.

Synthesis of dimethylformamide diethylacetal

The N , N , N ', N ' -tetramethylformamidinium salt reacts with aqueous sodium cyanide to form bis (dimethylamino) acetonitrile>

Synthesis of bis (dimethylamino) acetonitrile

With anhydrous hydrocyanic acid , N , N , N ', N ' -tetramethylformamidinium chloride is converted into dimethylaminomalonic acid dinitrile in 92% yield

Synthesis of dimethylaminomalononitrile

N , N , N ', N ' -Tetramethylformamidinium chloride can be re-gaminated with cycloaliphatic amines to give the corresponding heterocyclic formamidines.

Transamination of tetramethylformamidinium chloride

More recently, the use of N , N , N ', N ' -tetramethylformamidinium chloride as a catalyst in the preparation of carboxylic acid chlorides from carboxylic acids and phosgene has been reported.

Strong bases such as B. Phenyllithium can abstract a proton from the formamidinium cation of N , N , N ', N ' -Tetramethylformamidiniumchlorid to form bis (dimethylamino) carbene.

Formation of bis (dimethylamino) carbene from N, N, N ′, N′-tetramethylformamidinium chloride

Individual evidence

  1. ↑ a b c d data sheet N, N, N ′, N′-tetramethylformamidinium chloride from Sigma-Aldrich , accessed on October 20, 2016 ( PDF ).
  2. ↑ a b c W. Kantlehner, P. Speh: acid amide reactions. LI. Note on the preparation of N, N, N ′, N′-tetramethylformamidinium chloride . In: Chem. Ber. tape 104 , no. 11 , 1971, p. 3714-3715 , doi : 10.1002 / cber.19711041136 .
  3. ^ A b c Z. Arnold: The preparation of tetramethylformamidinium salts and their vinylogues . In: Collect. Czech. Chem. Commun. tape 24 , 1959, pp. 760-765 , doi : 10.1135 / cccc19590760 .
  4. ↑ a b c d R.W. Alder, ME Blake, S. Bufali, CP Butts, AG Orpen, J. Schütz, SJ Williams: Preparation of tetraalkylformamidinium salts and related species as precursors to stable carbenes . In: J. Chem. Soc., Perkin Trans. Volume 1 , 2001, p. 1586–1593 , doi : 10.1039 / B104110J .
  5. ↑ a b A.M. Magill, KJ Cavell, BF Yates: Basicity of nucleophilic carbenes in aqueous and nonaqueous solvents - theoretical predictions . In: J. Am. Chem. Soc. tape 126 , no. 28 , 2004, pp. 8717-8724 , doi : 10.1021 / ja038973x .
  6. ↑ a b Patent DE1205528 : Process for the production of N-substituted amidines or their vinylogues. Registered on February 8, 1962 , published on November 25, 1965 , applicant: H. Bredereck, inventor: H. Bredereck, F. Effenberger, G. Simchen. ‌
  7. ↑ X. Tian, ​​T. Pape, NW Mitzel: Formamidinium Salts of Low Valent Metal Halide Anions MX 3 - (M = Ge, Sn) and M 2 X 6 2- (M = Ga, In) . In: Z. Naturforsch. 59b, no. 11-12 , 2004, pp. 1524-1531 , doi : 10.1515 / znb-2004-11-1224 .
  8. ↑ H. Bredereck, F. Effenberger, G. Simchen: acid amide reactions, XXXII. About acid amide dialkyl sulfate complexes . In: Chem. Ber. tape 96 , no. 5 , 1963, pp. 1350-1355 , doi : 10.1002 / cber.19630960526 .
  9. ↑ Patent US3707553 : Tetramethylformamidinium arenesulfonates and method of preparation. Filed August 24, 1965 , published December 26, 1972 , Applicant: Armstrong Cork Co., Inventor: GE Bagley, AC Poshkus. ‌
  10. ↑ H. Schindlbauer: Reactions with dimethylformamide, 3rd edition. The reaction of arylsulfochlorides and arylsulfonic acids with dimethylformamide . In: monthly Chem. Band 100 , no. 5 , 1969, p. 1590-1595 , doi : 10.1007 / BF00900174 .
  11. ↑ Patent US5241099 : Process for the preparation of aminomethylene compounds. Registered on March 16, 1992 , published on August 31, 1993 , applicant: Bayer AG, inventor: H.-U. Blank, H. Kraus. ‌
  12. ↑ H. Bredereck, F. Effenberger, T. Brendle: Synthesis and reactions of Trisdimethylaminomethan . In: Angew. Chem. Band 78 , no. 2 , 1966, p. 147-148 , doi : 10.1002 / anie.19660780212 .
  13. ↑ Patent DE1217391 : Process for the production of tris-dimethylaminomethane. Applied on September 29, 1964 , published on December 8, 1966 , applicant: H. Bredereck, inventor: H. Bredereck, F. Effenberger, T. Brendle. ‌
  14. ↑ H. Bredereck, F. Effenberger, T. Brendle, H. Muffler: Orthoamide, V. Synthesis of Tris-dialkylamino-methanes . In: Chem. Ber. tape 101 , no. 5 , 1968, p. 1885–1888 , doi : 10.1002 / cber.19681010541 .
  15. ↑ H. Gold: The reaction of cyanuric chloride with dimethylformamide . In: Angew. Chem. Band 72 , no. 24 , 1960, pp. 956-959 , doi : 10.1002 / anie.19600722406 .
  16. ↑ H. Bredereck, G. Simchen, W. Kantlehner: Orthoamide, XVI. Synthesis of ON- and NN-acetals of the α-keto-carboxylic acid nitriles and of imino esters . In: Chem. Ber. tape 104 , no. 3 , 1971, p. 924-931 , doi : 10.1002 / cber.19711040331 .
  17. ^ A b H. Gold, O. Bayer: The representation of basic substituted malonic acid dinitrile . In: Chem. Ber. tape 94 , no. 10 , 1961, pp. 2594-2596 , doi : 10.1002 / cber.19610941004 .
  18. ↑ Patent EP1124783A1 : Method for producing carboxylic acid chlorides. Applied on November 4, 1998 , published on August 22, 2001 , applicant: BASF AG, inventor: J. Henkelmann, A. Stamm. ‌