Dimethyl reaction with ammonia

Other processes recently reported in the Hterature are the gas-phase reaction of lactonitnle [78-97-7] with ammonia and oxygen in the presence of molybdenum catalyst (86), or the vapor-phase reaction of dimethyl malonate with ammonia in the presence of dehydration catalyst (87). 

N10.9O% crysts, mp 136°. Prepd by sulfonating 2-ethylphenyl, nitrating in the 4,6 positions, conversion to the ani-sole with dimethyl sulfate in aniline, followed by reaction with ammonia in methanhl Refs l)Beil, not found 2)P.J.C.Fier-ens, et al, BuIlSocChimBelges 64, 658-66 (1955) CA 50, 11260(1956)... 

Reaction of 2-S-S-bis(5-methoxybenzimidazole) 1 with 3,5-dimethyl-4-methoxy-2-pyridine methyl carboxylate 2 followed by reaction with ammonia to give the carboxylate thioether 3. Compound 3 was oxidized to give the carboxylate sulfoxide 4 which was decarboxylated to give omeprazole 5. 

Direct ring syntheses are also available for the preparation of hydroxypyrazines. Thus, haloacylation of an a-aminoketone, followed by reaction with ammonia and oxidation represents a general synthesis of 5,6-disubstituted and 3,5,6-trisubstituted 2-hydroxypyrazines.339 This is illustrated by the preparation of 5,6-dimethyl-2-hydroxy-pyrazine (Scheme 39). Hydroxypyrazines are very conveniently... 

The marked activation of the iV-oxide function on the chlorine atom of 2-chloropyrazine 4-oxide and 2-ehloro-3,6-dimethylpyrazine 4-oxide is also demonstrated by the milder conditions under which these compounds react with ammonia and amines compared with chloro-pyrazine and 2-chloro-3,6-dimethyl pyrazine, respectively. Although 2-chloropyrazine 4-oxide undergoes the expected displacement reaction with ammonia on heating at 115°-120° for 2.5 hours, reaction at 140° for 16 hours gives 2,3-diaminopyrazine, possibly as a result of an addition-elimination reaction on the initially formed 2-amino-pyrazine 4-oxide (Scheme 47).417... 

Sulfate ions are excellent leaving groups. Like sulfonate esters, sulfate esters are good electrophiles. Nucleophiles react with sulfate esters to give alkylated products. For example, the reaction of dimethyl sulfate with ammonia gives a sulfate salt of methylamine, CH3NH CH3OSO3. 

A patent (726) has described the preparation of 2methyl-pyrazine by reaction with ammonia and air at 350° over a catalyst containing vanadium pentoxide and potassium sulfate a series of cyanomethylpyrazines has been prepared from the corresponding methylpyrazines by reaction with sodium amide in liquid ammonia followed by Af-methyl-A -phenylcyanamide in dioxane (644). 2-Hydroxyiminomethylpyrazine has been prepared from 2-methylpyrazine, sodium amide, and liquid ammonia with butyl nitrite (727, 728), and 2-hydroxy-iminomethyl-3,6-dimethyI-5-pentylpyrazine similarly from 2,3,5-trimethyl-6-pentylpyrazine (648). Nitrones (28) have been prepared from 23-and 2,5-dimethyl-and tetramethylpyrazine through the substituted methylpyridinium (perchlorates) (27) by reaction with p-nitroso-A, fV-dimethylaniline (729). Dehydrogenation of ethylpyrazine at 600° over a calcium cobaltous phosphate catalyst gives 2-vinyl-pyrazine (658). 

An example of this reaction is the synthesis of 4,6-dimethylpteridin-2-amine (1) from 2,4-dichloro-6-methyl-5-nitropyrimidine and aminoacetone. Initially 4-acetonylamino-2-chloro-6-methyl-5-nitropyrimidine is formed which, by reaction with ammonia, gives the corresponding pyrimidin-2-amine.132 This undergoes reductive cyclization to 4,6-dimethyl-7,8-dihydropteridin-2-amine, which may be subsequently oxidized (potassium permanganate) to l.133... 

The previously unknown l,2,3,6-tetrahydropyrazin-2-ones (270) are easily prepared by mixing 2,2-dimethyl-3-phenylazirine (271) with the methyl esters of a-amino-acids. " Another example of the use of this azirine is seen in its reaction with ammonia to give the amino-pyrazine (272) in 72% yield (Scheme 107). ... 

The property of f. to be local irritants of eyes and skin is reduced by ethoxylation. Manufacturing from RR is predominantly done via the fatty nitriles, which are made from fatty acids by reaction with ammonia. The nitriles are reduced by - hydrogenation (batch or continuous) into amines. The reaction conditions determine whether primary, secondary or tertiary amines result. Saturated f are formed when nitriles are hydrogenated at 80-140 °C and 1-4 MPa/lO O bar over Ni catalyst. Unsaturated f can be obtained with Raney Co or Cu-chromite as catalyst. Ammonia has to be present to suppress the formation of secondary amines. Saturated and unsaturated secondary amines are gained in yields of more than 90% if ammonia is vented from the reactor, the reaction temperature is 160-210 °C, and pressure is maintained at 5-10 MPa/50-100 bar. Trialkylamines are produced via the imine R-CH=NH and Schiff base R-CH=N-CH3 with Ni catalyst at 230 °C and 0.7 MPa/7 bar hydrogen pressure. Important amine types, which are the base for making dimethyl dialkyl ammonium compounds, are made by the following reaction ... 

The formation of the above anions ("enolate type) depend on equilibria between the carbon compounds, the base, and the solvent. To ensure a substantial concentration of the anionic synthons in solution the pA" of both the conjugated acid of the base and of the solvent must be higher than the pAT -value of the carbon compound. Alkali hydroxides in water (p/T, 16), alkoxides in the corresponding alcohols (pAT, 20), sodium amide in liquid ammonia (pATj 35), dimsyl sodium in dimethyl sulfoxide (pAT, = 35), sodium hydride, lithium amides, or lithium alkyls in ether or hydrocarbon solvents (pAT, > 40) are common combinations used in synthesis. Sometimes the bases (e.g. methoxides, amides, lithium alkyls) react as nucleophiles, in other words they do not abstract a proton, but their anion undergoes addition and substitution reactions with the carbon compound. If such is the case, sterically hindered bases are employed. A few examples are given below (H.O. House, 1972 I. Kuwajima, 1976). 

Acetaldehyde can be isolated and identified by the characteristic melting points of the crystalline compounds formed with hydrazines, semicarbazides, etc these derivatives of aldehydes can be separated by paper and column chromatography (104,113). Acetaldehyde has been separated quantitatively from other carbonyl compounds on an ion-exchange resin in the bisulfite form the aldehyde is then eluted from the column with a solution of sodium chloride (114). In larger quantities, acetaldehyde may be isolated by passing the vapor into ether, then saturating with dry ammonia acetaldehyde—ammonia crystallizes from the solution. Reactions with bisulfite, hydrazines, oximes, semicarb azides, and 5,5-dimethyl-1,3-cyclohexanedione [126-81 -8] (dimedone) have also been used to isolate acetaldehyde from various solutions. 

Diamine. 2,2-Dimethyl-l,3-propanediamine [7328-91-8] (5) has been prepared by amination of neopentyl glycol by treating the glycol with ammonia and hydrogen at 150—250°C at 10—31 MPa (1500—4500 psig) over a Ni catalyst. The diamine is useflil for preparation of crystalline polyureas by reaction with diisocyanates (36). 

Ak2o has been iastmmental ia developiag a new process for the stereospecific synthesis of 1,4-cyclohexane diisocyanate [7517-76-2] (21). This process, based on the conversion of poly(ethylene terephthalate) [25038-59-9] circumvents the elaborate fractional crystallisation procedures required for the existing -phenylenediamine [108-45-2] approaches. The synthesis starts with poly(ethylene terephthalate) (PET) (32) or phthaUc acid, which is converted to the dimethyl ester and hydrogenated to yield the cyclohexane-based diester (33). Subsequent reaction of the ester with ammonia provides the desired bisamide (34). The synthesis of the amide is the key... 

Pyrans and related compounds react with ammonia to give pyridines. A commercially useful example is the reaction of dehydroacetic acid (derived from diketene) with ammonia to give 2,6-dimethyl-4-pyridinone [7516-31 -6] via 2,6-dimethyl-4-pyridinone-3-carboxyhc acid [52403-25-5]. Chlorination of the pyridone gives clopidol [2971-90-6] (56), a coccidiostat (72,73). 

Zirconium tetrachloride is instantly hydrolyzed in water to zirconium oxide dichloride octahydrate [13520-92-8]. Zirconium tetrachloride exchanges chlorine for 0x0 bonds in the reaction with hydroxylic ligands, forming alkoxides from alcohols (see Alkoxides, METAl). Zirconium tetrachloride combines with many Lewis bases such as dimethyl sulfoxide, phosphoms oxychloride and amines including ammonia, ethers, and ketones. The zirconium organometalLic compounds ate all derived from zirconium tetrachloride. 

Dimethyl-1,2-dithiolylium perchlorate (488) when treated with ammonia at -5 °C underwent nucleophilic ring opening to (489). Subsequent ring closure with loss of H2S gave 4,5-dimethylisothiazole (490) in 85% yield (see Chapter 4.17). This reaction involved an initial attack of the ammonia at the unsubstituted 3-position. A small amount of the 3,4-dimethylisothiazole (491 15%) indicated that some attack of the ammonia also occurred at the 5-position. 

The reaction of the fervenulin 1-oxides 100 with secondary amines results in contraction of the 1,2,4-triazine ring to form 2-amino-5,7-dimethylimidazo[4,5-e] pyrimidine-4,6(5/7,7//)-diones 101. The reaction of the same fervenulin 1-oxides 100 with ammonia leads to the 1,2,4-triazine ring cleavage product, 1,3-dimethyl-5-imino-6-isonitrosouracil 102 (94KGS1253). 

J -methylpyrrolidone by conversion to the imine ( 7) by sequential reaction with triethyloxonium tetraf1uoroborate and then anhydrous ammonia. When this is reacted with 2,6-dimethyl-phenyl i socyanate, the centrally acting muscle relaxant xilobam (8) is formed. ... 

Poly(methyl 3-(l-oxypyridinyl)siloxane) was synthesized and shown to have catalytic activity in transacylation reactions of carboxylic and phosphoric acid derivatives. 3-(Methyldichlorosilyl)pyridine (1) was made by metallation of 3-bromopyridine with n-BuLi followed by reaction with excess MeSiCl3. 1 was hydrolyzed in aqueous ammonia to give hydroxyl terminated poly(methyl 3-pyridinylsiloxane) (2) which was end-blocked to polymer 3 with (Me3Si)2NH and Me3SiCl. Polymer 3 was N-oxidized with m-ClC6H4C03H to give 4. Species 1-4 were characterized by IR and H NMR spectra. MS of 1 and thermal analysis (DSC and TGA) of 2-4 are discussed. 3-(Trimethylsilyl)-pyridine 1-oxide (6), l,3-dimethyl-l,3-bis-3-(l-oxypyridinyl) disiloxane (7) and 4 were effective catalysts for conversion of benzoyl chloride to benzoic anhydride in CH2Cl2/aqueous NaHCC>3 suspensions and for hydrolysis of diphenyl phosphorochloridate in aqueous NaHCC>3. The latter had a ti/2 of less than 10 min at 23°C. 

A violent reaction occurred which shattered the flask when litre quantities of dimethyl sulfate and cone, aqueous ammonia were accidentally mixed. Use dilute ammonia in small quantities to destroy dimethyl sulfate [1], Similar incidents were noted previously with ammonia and other bases [2],... 

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