solo
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Green Methylating agent....comments
Dimethyl carbonate
Dimethyl carbonate, often abbreviated DMC, is a flammable clear liquid boiling at 90 °C, insoluble in water. It has recently found use as a
methylating reagent. Its main benefit over other methylating reagents such as iodomethane and dimethyl sulfate is its lesser toxicity and its
biodegradability.[1] Also, it is now prepared from catalytic oxidative carbonylation of methanol with oxygen, instead of from phosgene making its
production non-toxic and environmentally friendly.[1] This allows dimethyl carbonate to be considered a green reagent.
Dimethyl carbonate is able to methylate anilines, phenols and carboxylic acids, but many of these reactions require the use of an autoclave.[2] One
alternative involves the use of DBU, which allows methylation of carboxylic acids to occur in refluxing DMC.[2]
....................source,
http://en.wikipedia.org/wiki/Dimethyl_carbonate
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The Chemistry of Dimethyl Carbonate
PIETRO TUNDO* AND MAURIZIO SELVA
Acc. Chem. Res. 2002, 35, 706-716
ABSTRACT
Dimethyl carbonate (DMC) is a versatile compound that represents
an attractive eco-friendly alternative to both methyl halides (or
dimethyl sulfate) and phosgene for methylation and carbonylation
processes, respectively. In fact, the reactivity of DMC is tunable:
at T ) 90 °C, methoxycarbonylations take place, whereas at higher
reaction temperatures, methylation reactions are observed with a
variety of nucleophiles. In the particular case of substrates susceptible
to multiple alkylations (e.g., CH2-active compounds and
primary amines), DMC allows unprecedented selectivity toward
mono-C- and mono-N-methylation reactions. Nowadays produced
by a clean process, DMC possesses properties of nontoxicity and
biodegradability which makes it a true green reagent to use in
syntheses that prevent pollution at the source. Moreover, DMCmediated
methylations are catalytic reactions that use safe solids
(alkaline carbonates or zeolites), thereby avoiding the formation
of undesirable inorganic salts as byproducts. The reactivity of other
carbonates is reported as well: higher homologues of DMC (i.e.,
diethyl and dibenzyl carbonate), are excellent mono-C- and mono-
N-alkylating agents, whereas asymmetrical methyl alkyl carbonates
(ROCO2Me with R g C3) undergo methylation processes with a
chemoselectivity up to 99%.
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This seems like an excellent methylating agent , has anyone had any experience using this material to mono methylate amines?...........solo
Attachment: the chemistry of dimethyl carbonate.pdf (229kB)
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stoichiometric_steve
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the only reference i've come across was the n-methylation of indole using DMC. not that interesting, i admit 
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solo
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Highly selective zeolite-catalysed mono-N-alkylation of arylenediamines by dialkyl carbonates
Warren J. Ebenezer, Michael G. Hutchings, Ken Jones, David A. Lambert and Ian Watt
Tetrahedron Letters Volume 48, Issue 9, 26 February 2007, Pages 1641-1643
Abstract
Arylenediamines are mono-N-alkylated by dialkyl carbonates in the presence of NaY zeolite catalyst in a regioselective and nontoxic process.
Attachment: Highly selective zeolite-catalysed mono-N-alkylation of arylenediamines by dialkyl carbonates.pdf (101kB)
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solo
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Reference Information
Organic Carbonates
Abbas-Alli G. Shaikh, Swaminathan Sivaram
Chem. Rev. 96 (3), 951 -976, 1996.
Contents
* I.Introduction
* II.Synthesis, Isolation, and Characterization of Carbonic Acid
* III. Carbonates
* IV.Classification of Carbonates
* V.Physical Properties of Carbonates
* VI.Methods of Preparation of Organic Carbonates
* A.Phosgenation Technique
* B.Oxidative Carbonylation of Alcohols/Phenols
* C.Reaction of Urea with Alcohols/Phenols
* D.Reaction of Oxiranes with Carbon Dioxide
* E.Use of Metal Carbonate
* F.Carbonate Interchange Reaction
* 1.Dialkyl to Dialkyl Carbonates
* 2.Dialkyl to Alkyl Aryl Carbonate
* 3.Dialkyl to Diaryl Carbonates
* 4.Alkyl Aryl Carbonate to Diaryl Carbonate
* 5.Use of Activated Carbonates
* G.Other Methods of Synthesis of Dialkyl Carbonates
* 1.From Halohydrins
* 2.From Alcohols and Carbon Monoxide by Elemental Sulfur
* 3.Alicyclic Carbonate from Halogenated Carbonates
* 4.From Carbon Dioxide
* 5.Alkylation of Alkali Metal Carbonate
* VII.Applications of Organic Carbonates
* A.Application of Dimethyl Carbonate as Alkylating Agent under GL-PTC
* 1.Reaction with Phenol and Thiophenol
* 2.Reaction with Primary Aromatic Amines
* 3.Reaction with Arylacetonitriles
* B.Other Applications of Organic Carbonates
* 1.Dimethyl and Diethyl Carbonates
* 2.Diphenyl Carbonate
* 3.Allyl Carbonates
* 4.Cyclic Carbonates
* 5.Dialkyl Carbonates as Lubricants
* 6.Agriculatural Applications
* 7.Applications in Medicinal Chemistry
* 8.Miscellaneous Applications
* C.Economic Aspects
* VIII.Future Perspectives
* IX.Acknowledgement
* X.References
Introduction
Carbonic acid which is unstable at room temperature has been isolated in its pure state at lower temperature and characterized spectroscopically.1,2
The diesterification of carbonic acid with hydroxy compounds leads to the formation of stable organic compounds known as organic carbonates. Depending
upon the nature of hydroxy compounds, the resulting carbonates are either dialkyl, diaryl, or substituted dialkyl diaryl carbonates. Among the various
types of organic carbonates, the simplest one is dimethyl carbonate. The production of dimethyl carbonate3,4 on an industrial scale by catalytic
oxycarbonylation of methanol has provided a great impetus to its use as a safe analog for phosgene or dimethyl sulfate in the manufacture of many
useful organic compounds.
In spite of burgeoning applications, there is no compilation of the literature on the synthesis and utility of organic carbonates. The present review,
therefore, attempts to provide a comprehensive survey of the currently available literature on organic carbonates.
Attachment: Organic Carbonates.pdf (379kB)
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chemrox
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I'm wondering if there's a prep besides the one using CO
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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smuv
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Well from phosgene...
Small amounts are made in chloroform inhibited with methanol. Phosgene formed from decomposition of chloroform reacts with the methanol forming
dimethyl carbonate and HCl (IIRC).
It can also be synthesized from urea:
ethylene glycol + urea --> ethylene carbonate + 2NH3
methanol + ethylene carbonate --> Dimethyl carbonate + ethylene glycol (transesterfication)
If you are interested in the above route see Green Chemistry, 2003, 5, 429-32
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Nicodem
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I've never seen dimethyl carbonate being used for methylating aliphatic amines. It can however be used for N-methylating anilines and other
relatively acidic NH groups.
Preparation of dimethyl carbonate was already discussed here: https://sciencemadness.org/talk/viewthread.php?tid=9791
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solo
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| Quote: | Originally posted by Nicodem
I've never seen dimethyl carbonate being used for methylating aliphatic amines. |
Selective N-methylation of primary aliphatic amines with dimethyl carbonate in the presence of alkali cation exchanged Y-faujasites
Maurizio Selva and Pietro Tundo
Tetrahedron Letters Volume 44, Issue 44, 27 October 2003, Pages 8139-8142
Abstract
The N-methylation of aliphatic amines [XC6H4(CH2)nNH2; n=1, X=H (1a), o-MeO (1b), p-MeO (1c); n=2, X=H (2a), o-MeO (2b); 1d: PhCH(Me)NH2] with
dimethyl carbonate (DMC) is efficiently catalysed by NaY faujasite: on condition that CO2 (a co-product of the reaction) is carefully removed,
N-methyl- and N,N-dimethyl-amines (RNHMe and RNMe2) are obtained in good overall yields (70–90%). Otherwise, in the presence of CO2, carbamates
(RNHCO2Me) form competitively to a large extent. The reaction probably proceeds through a BAl2 displacement of the amine on DMC.
Attachment: Selective N-methylation of primary aliphatic amines with dimethyl carbonate in the presence of alkali cation exchanged Y (212kB)
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Methyl.Magic
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personally I use trimethylphosphate : it's relatively nontoxic , cheap and more effective than DMC.
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solo
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| Quote: | Originally posted by Methyl.Magic
personally I use trimethylphosphate : it's relatively nontoxic , cheap and more effective than DMC. |
Can you provide some reference for your procedure, a reference is fine i can secure the study, and have you methylated primary aliphatic amines with
this before?......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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