scholarly journals Methylation of Eugenol Using Dimethyl Carbonate and Bentonite as Catalyst

2015 ◽  
Vol 15 (3) ◽  
pp. 256-262 ◽  
Author(s):  
Dina Asnawati ◽  
I Made Sudarma ◽  
Emmy Yuanita ◽  
Baiq Fadila Arlina ◽  
Saprini Hamdiani ◽  
...  
Keyword(s):  
Functional Groups ◽  
Dimethyl Sulphate ◽  
Dimethyl Carbonate ◽  
Methyl Halides ◽  
Light Yellow ◽  
Light Yellow Liquid ◽  
Low Toxicity

Eugenol is a compound with a variety of reactive functional groups such as allyl, hydroxy and methoxy. The presence of the functional groups brings eugenol possible to undertake the transformation into various derivative compounds with diverse activities. One of the simple and possible transformations is methylation or alkylation. Commonly, methyl halides and dimethyl sulphate are used as methylation agent. However, those kinds of methylation agents are toxic and carcinogenic. In this research dimethyl carbonate, an alternative methylation agent is used, because of its low toxicity, green, and economic. The synthesis has been carried out by using a catalyst. Bentonite was activated by heating to a temperature using 300 °C. Methylation was shown by the formation of a light yellow liquid (25.71% yield). The structures of products were characterized by GC-MS and obtained a compound, namely bis eugenol (4-allyl-2-methoxyphenoxy) methane (2.37% yield).

1,2,3-Trimethoxypropane, a glycerol-based solvent with low toxicity: new utilization for the reduction of nitrile, nitro, ester, and acid functional groups with TMDS and a metal catalyst

2013 ◽  
Vol 15 (11) ◽  
pp. 3020 ◽  
Author(s):  
Marc Sutter ◽  
Leyla Pehlivan ◽  
Romain Lafon ◽  
Wissam Dayoub ◽  
Yann Raoul ◽  
...  
Keyword(s):  
Functional Groups ◽  
Metal Catalyst ◽  
Low Toxicity

Hypervalent Iodine-mediated/Catalyzed Oxidative Cycloisomerization/Annulation of Alkynes for Metal-free Synthesis of Oxazoles

2020 ◽  
Vol 24 (18) ◽  
pp. 2048-2069
Author(s):  
Akio Saito
Keyword(s):  
Functional Groups ◽  
Single Step ◽  
Biologically Active ◽  
Hypervalent Iodine ◽  
Sustainable Chemistry ◽  
Metal Free ◽  
Triple Bonds ◽  
Iodine Species ◽  
Low Toxicity ◽  
Synthetic Intermediates

Since oxazoles have found widespread applications not only as synthetic intermediates but also as biologically active compounds, much effort has been focused on developing novel and efficient methods for the synthesis of this heterocycle. From the viewpoint of green and sustainable chemistry, hypervalent iodine and other halogen reagents have gained increasing popularity in metal-free oxidative transformation due to their low toxicity, transition-metal-like reactivity, high stability, easy handling and other benefits. In this account, our two approaches to the metal-free synthesis of oxazoles by means of a peculiar activation of alkynes by iodine species are described with the related contexts. One is iodine(III)-mediated/catalyzed oxidative cycloisomerization reactions of N-propargyl amides for the preparation of oxazoles bearing various functional groups at their side chains. In these reactions, iodine(III) species works as a donor of various heteroatomic functional groups as well as an activator of carbon-carbon triple bonds in a single step. Furthermore, this methodology can be extended to iodine(III)-mediated/catalyzed oxidative annulation of alkynes and nitriles as another approach, in which heteroatoms on iodine(III) species are incorporated in the azole rings.

scholarly journals New developments in dimethyl carbonate chemistry

2001 ◽  
Vol 73 (7) ◽  
pp. 1117-1124 ◽  
Author(s):  
Pietro Tundo
Keyword(s):  
Aromatic Amines ◽  
Dimethyl Carbonate ◽  
Catalytic Amount ◽  
Inorganic Salts ◽  
Cyclic Ketones ◽  
Carbonate Chemistry ◽  
Methyl Halides ◽  
New Developments ◽  
Primary Aromatic Amines ◽  
By Products

Dimethylcarbonate (DMC) is a valuable methylating reagent which can replace methyl halides and dimethylsulfate in the methylation of a variety of nucleophiles. It couples tunable reactivity and unprecedented selectivity toward mono-C- and mono-N-methylation in the reactions of acidic CH2 and primary aromatic amines, respectively. In addition, it is a prototype example of a green reagent, since it is nontoxic, made by a clean process, and biodegradable, and it reacts in the presence of a catalytic amount of base thereby avoiding the formation of undesirable inorganic salts as by-products. Other remarkable reactions are those where DMC behaves as an oxidant: cyclic ketones are transformed into a,w-dimethyl esters with a reaction of atom efficiency of 1.0.

C-Methylation Of Organic Substrates. A Comprehensive Overview. Part Iva. Methylating Agents Other Than Methane, Methanol, And Methyl Metals

2021 ◽  
Vol 01 ◽  
Author(s):  
Saad Moulay
Keyword(s):  
Transition Metal Complexes ◽  
Dimethyl Carbonate ◽  
Emission Tomography ◽  
Dimethyl Formamide ◽  
Organic Substrates ◽  
Comprehensive Overview ◽  
Methyl Halides ◽  
Aromatic Substrates ◽  
Positron Emission ◽  
Methylating Agents

: C-Methylation of organic substrates was accomplished with a number of methylating agents other than methane, methanol, and methyl metals. They include methyl halides (MeX, X = I, Br, Cl, F), methyl-containing halogenated reagents, methyl peroxides, dimethyl carbonate (DMC), dimethylsulfoxide (DMSO), N,N-dimethyl formamide (DMF), diazomethane, formate salts, trioxane, CO/H2, CO2/H2, and dimethyl ether (DME). Under particular conditions, some methyl-containing molecules such as polymethylbenzenes, methylhydrazine, tris(diethylamino)sulfonium difluorotrimethylsilicate, methyl tosylate, long-chain alkyl alcohols, and acetic acid unexpectedly C-methylated a variety of organic substrates. A few cases of C-methylation only were reported to occur in the absence of catalysts. Otherwise, transition metal complexes as catalysts in conjunction with specific ligands and bases were ubiquitously present in most C-methylation reactions. Of the reactions, Suzuki-Miyaura-type cross-coupling remained of paramount importance in making 11CH3-bearing positron emission tomography tracers (PETs), one of the best applications of such methylation. Methylation proceeded at C(aromatic)-X, C(sp3)-X C(sp2)-X, and C(sp)-X of substrates (X = H, halogen). Ortho-methylation was regioselectively observed with aromatic substrates when they bear moieties such as pyridyl, pyrimidyl, amide, and imine functionalities, which were accordingly coined ‘ortho-directing groups’.

2-Tolyloamine. Determination in workplace air

2018 ◽  
Vol 34 (1(95)) ◽  
pp. 99-109
Author(s):  
Anna Jeżewska ◽  
Agnieszka Woźnica
Keyword(s):  
Sodium Hydroxide Solution ◽  
Array Detector ◽  
Determination Limit ◽  
Liquid Chromatograph ◽  
Total Uncertainty ◽  
Selective Determination ◽  
Light Yellow ◽  
Validation Parameters ◽  
Workplace Air ◽  
Light Yellow Liquid

o-Toluidine (2-TA) exists at ambient temperature as a light yellow liquid which rapidly darkens when exposed to air and light. It is used primarily in manufacturing dyestuffs, it is also used in the production of pesticides, rubber and in organic synthesis. 2-TA may cause cancer. The aim of this study was to determine concentrations of 2-TA in workplace air in the range from 1/10 to 2 MAC values. The study was performed using a liquid chromatograph (HPLC) with a diode array detector (DAD) with a column Ultra C18 (250 × 4.6 mm; 5 µm). This method is based on the adsorption of 2-TA on a glass fiber filter coated with sulfuric acid and extraction with sodium hydroxide solution. After derivatization with 3,5-dinitrobenzoyl chloride, 2-TA is analyzed as derivative with chromatography. The method was validated in accordance with Standard No. EN 482. The working range was from 0.05 to 1 mg/m3 for a 36 L air sample. The following validation parameters were determined: detection limit 3.48 ng/ml, determination limit 10.43 ng/ml, overall accuracy of the method 5.22%, relative total uncertainty of the method 11.45%. The analytical method described in this paper enables selective determination of 2-TA in workplace air in the presence of other substances at concentrations from 0.05 mg/m³ (1/10 MAC value). The method is precise, accurate and it meets the criteria for the procedures for measuring chemical agents listed in Standard No. EN 482. The developed method of determining 2-TA has been recorded as an analytical procedure (see Appendix).

Green approaches to highly selective processes: Reactions of dimethyl carbonate over both zeolites and base catalysts

2007 ◽  
Vol 79 (11) ◽  
pp. 1855-1867 ◽  
Author(s):  
Maurizio Selva
Keyword(s):  
Dimethyl Carbonate ◽  
Dimethyl Sulfate ◽  
Industrial Processes ◽  
Methyl Halides ◽  
Base Catalysts ◽  
Aminobenzoic Acids ◽  
Basic Catalysts ◽  
Primary Aromatic Amines ◽  
Methyl Derivatives ◽  
Very High

Nowadays available by clean industrial processes, dimethyl carbonate (DMC) possesses properties of nontoxicity and biodegradability which make it a true green reagent/solvent to devise syntheses that prevent pollution at the source. In particular, the versatile reactivity of DMC allows both methylation and carboxymethylation protocols that can replace conventional and highly noxious reagents such as methyl halides (and dimethyl sulfate, DMS) and phosgene. In the field of DMC-mediated methylations, representative examples are the reactions of DMC with CH2-active compounds and primary aromatic amines. In the presence of organic/inorganic bases or zeolites (faujasites) catalysts, these processes proceed with unprecedented selectivity (up to 99 %, at complete conversion) toward the corresponding mono-C- and mono-N-methyl derivatives, a result hitherto not possible with conventional alkylation reagents. In the case of ambident amines (e.g., aminophenols, aminobenzyl alcohols, aminobenzoic acids, and aminobenzamides), the unique combination of DMC and zeolites allows not only a very high mono-N-methyl selectivity, but also a complete chemoselectivity toward the amino group. The other nucleophilic functionalities (OH, CO2H, CH2OH, CONH2) are fully preserved from alkylation and/or transesterification reactions, usually observed over basic catalysts.

scholarly journals Lewis acidic FeCl3 promoted 2-aza-Cope rearrangement to afford α-substituted homoallylamines in dimethyl carbonate

RSC Advances ◽  
2019 ◽  
Vol 9 (31) ◽  
pp. 18013-18017 ◽  
Author(s):  
Karthik Gadde ◽  
Jonas Daelemans ◽  
Bert U. W. Maes ◽  
Kourosch Abbaspour Tehrani
Keyword(s):  
Functional Groups ◽  
Dimethyl Carbonate ◽  
Current Work ◽  
Cope Rearrangement

The current work shows an iron-catalyzed 2-aza-Cope rearrangement in dimethyl carbonate for the synthesis of a wide variety of α-substituted homoallylamines from readily accessible starting materials with diverse functional groups.

NUCLEOPHILIC DISPLACEMENT OF METHYL SULPHONIC ESTERS BY HYDROXIDE ION IN WATER

1960 ◽  
Vol 38 (11) ◽  
pp. 2033-2038 ◽  
Author(s):  
S. Hartman ◽  
R. E. Robertson
Keyword(s):  
Dimethyl Sulphate ◽  
Solvation Shell ◽  
Temperature Dependent ◽  
Characteristic Difference ◽  
Initial State ◽  
Methyl Halides ◽  
Methyl Carbon ◽  
Nucleophilic Displacement ◽  
The Difference ◽  
The Stability

Rate data for the reaction between OH− and methyl benzenesulphonate, methyl methanesulphonate, and dimethyl sulphate in water are determined for a series of temperatures. The corresponding [Formula: see text]ratio are found to be 3 to 6 times smaller than those values characterizing the reaction for the methyl halides, and the ratios in all cases are temperature dependent. While the stability of the initial state solvation shell undoubtedly contributes to the difference between the halides and sulphonates in these reactions, it is probable that differences in nucleophilic interaction between the oxygen of the water molecule and the partially empty p orbital of the methyl carbon is a more important factor in determining the characteristic difference.

Notizen: Reaktionen mit Dimethylcarbonat, 5 Methylierung der Pyrimidin-Basen der Nucleinsäuren / Reactions with Dimethyl Carbonate, 5 Methylation of the Pyrimidine Bases of Nucleic Acids

1989 ◽  
Vol 44 (7) ◽  
pp. 863-865 ◽  
Author(s):  
Helmut Jansen in de Wal ◽  
Manfred Lissel
Keyword(s):  
Nucleic Acids ◽  
Dimethyl Sulphate ◽  
Dimethyl Carbonate ◽  
Pyrimidine Bases ◽  
Higher Temperature

The methylation of the pyrimidine bases of nucleic acids by dimethyl carbonate is described compared to dimethyl sulphate. The reaction needs higher temperature, a base and the help of 18-crown-6 and DMF as cosolvent.

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