Dimethyl preparation

DiethylaminophenyldicMorQphospMne, (C2Hs)2N.CgH4.PCl2.— This is obtained when the dimethyKniline in the corresponding dimethyl preparation is replaced by diethylaniline. The product is a reddish oil, easily soluble in benzene, ether or alcohol. 

Me2NCH2) C2H5)(Me)C-OOC Ph-HCI. Colourless crystalline powder with a bitter taste, m.p. 177-179"C. Prepared by the action of ethyl magnesium bromide on dimethyl-aminoaceione. It is a local anaesthetic, mainly used to produce spinal anaesthesia. 

Dimeihylamine, C2H7N, (CH3)2NH. Colourless, inflammable liquid with an ammoniacal odour, mp -96" C, b.p. 7°C. Occurs naturally in herring brine. Prepared in the laboratory by treating nitrosodimetbyl-aniline with a hot solution of sodium hydroxide. Dimethylamine is largely used in the manufacture of other chemicals. These include the solvents dimethylacetamide and dimethyl-formamide, the rocket propellant unsym-metrical dimethylhydrazine, surface-active agents, herbicides, fungicides and rubber accelerators. 

Dissolve log. of powdered toluene-p-sulphonamide in 6o ml. of 10% aqueous sodium hydroxide (2 5 mols.) diluted with 50 ml. of water to moderate the reaction. Then, using the same precautions as in the previous preparation, add 127 ml. (17 g., 2 3 mols.) of dimethyl sulphate and shake the mixture vigorously. The crystalline dimethylamide rapidly separates from the warm... 

This preparation illustrates the use of dimethyl sulphate to convert a primary amino group into the secondary monomethylamino group, without the methy-lation proceeding to the tertiary dimethylamino stage. The methylation of anthranilic acid is arrested at the monomethylamino stage by using i-i molecular equiN alents of sodium hydroxide and of dimethyl sulphate. The reactions can be considered as ... 

Alkyl sulphates. The dimethyl and diethyl esters may be prepared infer alia by the interaction of chlorosulphonic acid with the anhydrous alcohol, followed by distillation of the resulting alkyl sulphuric acid under diminished pressure, for example ... 

The preparation of these compounds in the laboratory is not recommended and is rarely worth while because of the cheapness of the commercial products. Dimethyl sulphate is a heavy liquid, boiling at 188-6°, and is practically without odour. The vapour is highly poisonous and the substance should only be used in a fume cupboard with a good draught. The liquid itself is readily absorbed through the skin, with toxic results. 

I) An alternative procedure is to cool the solution containing the sodium sul. phanilate and sodium nitrite in a bath of crushed ice to about 5° and then add 10-5 ml. of concentrated hydrochloric acid diluted with an equal volume of water slowly and with stirring the temperature must not be allowed to rise above 10 and an excess of nitrous acid should be present (the solution is tested after standing for 5 minutes). The subsequent stages in the preparation—addition of dimethyl-aniline solution, etc.—are as above. 

Methyl and ethyl ethers of phenols are most conveniently prepared by alkylation with dimethyl sulphate and diethyl sulphate respectively in weakly alkaline solution, for example ... 

The preparation of 2 4-dimethyl-3 5-dicarbethoxypyrrole (II) is an example of the Knorr synthesis of pyrrole derivatives, involving the reaction of an -aminoketone (or a derivative thereof) with a reactive methylene ketone (or a derivative thereof). The stages In the present synthesis from ethyl acetoacetate (I) may be represented as follows ... 

Michler s ketone is prepared industrially by the interaction of phosgene (COCl,) and dimethyl aniline. 

Silcones are important products of silicon. They may be prepared by hydrolyzing a silicon organic chloride, such as dimethyl silicon chloride. Hydrolysis and condensation of various substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones, ranging from liquids to hard, glasslike solids with many useful properties. 

The desired pyridylamine was obtained in 69 % overall yield by monomethylation of 2-(aminomethyl)pyridine following a literature procedure (Scheme 4.14). First amine 4.48 was converted into formamide 4.49, through reaction with the in situ prepared mixed anhydride of acetic acid and formic acid. Reduction of 4.49 with borane dimethyl sulfide complex produced diamine 4.50. This compound could be used successfully in the Mannich reaction with 4.39, affording crude 4.51 in 92 % yield (Scheme 4.15). Analogous to 4.44, 4.51 also coordinates to copper(II) in water, as indicated by a shift of the UV-absorption maximum from 296 nm to 308 nm. 

Pyridyl)hydrazine (Aldrich), 4-acetylpyridine (Acros), N,N,N -trimethylethylenediamine (Aldrich), methylrhenium trioxide (Aldrich), InQj (Aldrich), Cu(N0j)2-3H20 (Merck), Ni(N03)2-6Il20 (Merck), Yb(OTf)3(Fluka), Sc(OTf)3 (Fluka), 2-(aminomethyl)pyridine (Acros), benzylideneacetone (Aldrich), and chalcone (Aldrich) were of the highest purity available. Borane dimethyl sulfide (2M solution in THE) was obtained from Aldrich. Methyl vinyl ketone was distilled prior to use. Cyclopentadiene was prepared from its dimer immediately before use. (R)-l-acetyl-5-isopropoxy-3-pyrrolin-2-one (4.15) has been kindly provided by Prof H. Hiemstra (University of Amsterdam). 

Note 2. Prepared by introducing gaseous HCl at -10°C into a mixture of 30 g of paraformaldehyde (corresponding to 1 mol of formaldehyde) and 1 mol of ethanol, until copious fumes escaped from the mixture. This was cooled (without stirring) to -70°C and the upper layer was decanted from the solid (frozen hydrochloric acid) and mixed with 50 g of yy-diethyl(or dimethyl)aniline. Subsequent distillation in a partial water-pump vacuum afforded the desired chloroether (b.p. about 40°C/40-50 mmHg). 

The dimethyl allylphosphonate 352 is prepared by the reaction of allylic acetates with trimethyl phosphite[221]. 

The carbonylation of 2-methyl-3-butyn-2-oI (50) in benzene gives teraconic anhydride (51). Fulgide (53) (a dimethylenesuccinic anhydride derivative), which is a photochromic compound, can be prepared by the carbonylation of 2,5-dimethyl-3-hexyne-2,5-diol (52)[21], The reaction proceeds under milder conditions when PdlOAc) is used as a catalyst in the presence of iodine [23],... 

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