Aminals, dialkyl

In the previous section, aminomethylenemalonates were obtained in the reactions of amines and alkoxymethylenemalonates. The latter were prepared in a separate step from dialkyl malonates and alkyl orthoformate. Aminomethylenemalonates can also be synthetized in a one-pot procedure, starting directly from the amine, dialkyl malonate, and alkyl orthoformate or its equivalent. 

Amines from N-nitroso compounds. Aromatic N-nitroso compounds are reduced by iron pentacarbonyl in boiling di-n-butyl ether to the corresponding amines. Dialkyl-nitrosoamines afford ureas. ... 

Entry Amine Dialkyl carbonate Catalyst T (°C) Time (h) Yield of urethane ( /.)... 

Alkynes and dialkyl alanes form dialkylalkynyl alanes almost quantitatively (with liberation of H2) if one starts from the amine-dialkyl alane (e.g., the trialkylamine adduct) (31) ... 

Synthetic application. The synthetic applications of the Atherton-Todd reaction include preparation of diatkyl amidophosphates and di- or trialkyl phosphates by in situ condensation of the intermediately formed dialkyl chlorophosphates with N-H or 0-H containing substrates. Thus, when the reaction takes place in an excess of the basic compounds (primary or secondary amines), dialkyl phosphoramides are formed as final products [81],... 

Das et al. [29] developed a simple, efficient, cost-effective, and metal-free four-component coupling reaction of aldehydes, amines, dialkyl acetylenedicaiboxyl-ates, and nitromethane for the synthesis of corresponding 1,2,3,4-tetra-substituted pyrroles 6 using molecular iodine as a catalyst (Scheme 10.4). 

Das B, Bhunia N, Lingaiah MA (2011) Simple and elficient metal-free synthesis of tetra-substituted pyrroles by iodine-catalyzed four-component coupling reaction of aldehydes, amines, dialkyl acetylenedicarboxylates, and nitromethane. Synthesis 2011 3471-3474 Khan AT, Ghosh A, Khan MM (2012) One-pot four-component domino reaction for the synthesis of substituted dihydro-2-oxypyrrole catalyzed by molecular iodine. Tetrahedron Lett 53 2622-2626... 

Additives acting on the pour point also modify the crystal size and, in addition, decrease the cohesive forces between crystals, allowing flow at lower temperatures. These additives are also copolymers containing vinyl esters, alkyl acrylates, or alkyl fumarates. In addition, formulations containing surfactants, such as the amides or fatty acid salts and long-chain dialkyl-amines, have an effect both on the cold filter plugging point and the pour point. 

A pletliora of different SA systems have been reported in tire literature. Examples include organosilanes on hydroxylated surfaces, alkanetliiols on gold, silver, copper and platinum, dialkyl disulphides on gold, alcohols and amines on platinum and carboxyl acids on aluminium oxide and silver. Some examples and references can be found in [123]. More recently also phosphonic and phosphoric esters on aluminium oxides have been reported [124, 125]. Only a small selection out of tliis number of SA systems can be presented here and properties such as kinetics, tliennal, chemical and mechanical stability are briefly presented for alkanetliiols on gold as an example. 

The reaction proceeds most readily wfth alkylaryl, dialkyl, and cyclic ketones, but the crude product may contain some secondary or tertiary amine. 

In the absence of a tertiary amine, the initial reaction is again the formatfon of a trialkyl phosphite and hydrogen chloride. The latter now reacts rapidly with the trialkyl phosphite to give the alkyl chloride and the dialkyl hydrogen... 

By the hydrolysis of dialkyl cyanamides with dilute sulphuric acid this method gives pure secondary amines. The appropriate dialkyl cyanamide is prepared by treating sodium cyanamide (itself obtained in solution from... 

A convenient method for preparing pure AW-dialkyl anilines and substituted anilines directly from the corresponding amines consists in heating the latter with trialkyl orthophosphates ... 

Carbocations stabilized by functional groups can also effect 3-alkylalion of indoles. From a synthetic point of view the most important are jV.jV-dialkyl-methyleneiminium ions which can be generated under Mannich conditions from formaldehyde and secondary amines[13]. The products, 3-(A/,A-dialkyl-aminornethyl)indoles, are useful synthetic intermediates (see Chapter 12). 

N-(2-thiazolyl)dithiocarbamates are prepared by the action of carbon disulfide on 2-aminothiazoles (see Section III.3.C and Ref. 505). When refluxed with secondary amines these heterocyclic dithiocarbamates yield l,T-dialkyl-3-(2-thiazoIyI)thioureas (261) (491). 

Secondary amines give only a monosubstituted product. Both of these reactions are thermally reversible. The product with ammonia (3,3, 3 -nitrilottispropionamide [2664-61-1C H gN O ) (5) is frequently found in crystalline acrylamide as a minor impurity and affects the free-radical polymerisation. An extensive study (8) has determined the stmctural requirements of the amines to form thermally reversible products. Unsymmetrical dialkyl hydrasines add through the unsubstituted nitrogen in basic medium and through the substituted nitrogen in acidic medium (9)). 

CycHc carbonates are made by treating 1,2-diols with dialkyl carbonates using an alkyl ammonium and tertiary amine catalyst. The combination of propylene glycol and dimethyl carbonate has been reported to result in a 98% yield of propylene carbonate (21). 

Zinc dialkyl dithiophosphates are the primary oxidation inhibitors in combining these functions with antiwear properties in automotive oils and high pressure hydrauhc fluids. Their production volume is followed by aromatic amines, sulfurized olefins, and phenols (22). 

Dialkyl peroxydicarboaates are used primarily as free-radical iaitiators for viayl monomer po1ymeri2ations (18,208). Dialkyl peroxydicarboaate decompositioas are accelerated by certaia metals, coaceatrated sulfuric acid, and amines (44). Violent decompositions can occur with neat or highly concentrated peroxides. As with most peroxides, they Hberate iodine from acidified iodides. In the presence of copper ions and suitable substrates, dialkyl peroxydicarbonates have been used to synthesi2e alkyl carbonates (44) ... 

The pigments are manufactured either by reaction of the dianhydride with an amine or N,N -diaLkylation of the diimide. They are characterized by high tinctorial strength, excellent solvent stabiUty, very good weatherfastness, moderate brightness, and range in color from red to violet. An exception is the dianhydride which is not stable to alkah. 

Elimination. Ahphatic amine oxides having an ahphatic hydrogen P to the nitrogen form olefins and diaLkyl hydroxylamines when heated. This reaction is known as the Cope elimination (17)... 

All lation. Alkylating agents such as diaLkyl sulfates and alkyl hahdes react with ahphatic amine oxides to form trialkylalkoxyammonium quaternaries. For example (33), methyl iodide reacts with trimethyl amine oxide to form trimethylmethoxyammonium iodide... 

QuaterniZation. Quaternary ammonium compounds are formed by alkylation of alkyl, alkyl dimethyl, dialkyl, and dialkylmethyl fatty amines with methyl chloride, dimethyl sulfate, or benzyl chloride (1,3,7,12,29). 

The single largest market use for quaternary fatty amines is in fabric softeners. Monoalkyl quaternaries (chloride) have been used in Hquid detergent softener antistat formulations (LDSA), dialkyl dimethyl quaternaries (chloride) in the rinse cycle, and dialkyl dimethyl quaternaries (sulfate) as dryer softeners. 

A AlI lation. A number of methods are available for preparation of A/-alkyl and A[,A/-dialkyl derivatives of aromatic amines. Passing a mixture of aniline and methanol over a copper—zinc oxide catalyst at 250°C and 101 kPa (1 atm) reportedly gives /V-methylaniline [100-61-8] in 96% yield (1). Heating aniline with methanol under pressure or with excess methanol produces /V, /V-dimethylaniline [121 -69-7] (2,3). 

SuIfona.tlon, Sulfonation is a common reaction with dialkyl sulfates, either by slow decomposition on heating with the release of SO or by attack at the sulfur end of the O—S bond (63). Reaction products are usually the dimethyl ether, methanol, sulfonic acid, and methyl sulfonates, corresponding to both routes. Reactive aromatics are commonly those with higher reactivity to electrophilic substitution at temperatures > 100° C. Tn phenylamine, diphenylmethylamine, anisole, and diphenyl ether exhibit ring sulfonation at 150—160°C, 140°C, 155—160°C, and 180—190°C, respectively, but diphenyl ketone and benzyl methyl ether do not react up to 190°C. Diphenyl amine methylates and then sulfonates. Catalysis of sulfonation of anthraquinone by dimethyl sulfate occurs with thaHium(III) oxide or mercury(II) oxide at 170°C. Alkyl interchange also gives sulfation. 

The N,]S -dialkyl-/)-PDAs are manufactured by reductively alkylating -PDA with ketones. Alternatively, these compounds can be prepared from the ketone and -lutroaruline with catalytic hydrogenation. The /V-alkyl-/V-aryl- -PDAs are made by reductively alkylating -nitro-, -nitroso-, or /)-aminodipheny1 amine with ketones. The AijAT-dialkyl- PDAs are made by condensing various anilines with hydroquinone in the presence of an acid catalyst (see Amines-aromatic,phenylenediamines). 

Dialkyl esters of 3,3 -thiodipropionic acid (53), cycHc phosphonites such as neopentylphenyl phosphite, derivatives of phosphaphenathrene-lO-oxide (54), secondary aromatic amines, eg, diphenylamine (55), and epoxidi2ed soybean oils (56) are effective stabili2ers for preventing discoloration of cellulose esters during thermal processing. 

Protonated /V-chloroalkyl amines under the influence of heat or uv light rearrange to piperidines or pyrroHdines (Hofmann-Lriffler reaction) (88). The free-radical addition of alkyl and dialkyl-/V-chloramines to olefins and acetylenes yields P-chloroalkji-, P-chloroalkenyl-, and 8-chloroalkenylamines (89). Various N-hiomo- and N-chloropolyfluoroaLkylarnines have been synthesized whose addition products to olefinic double bonds can be photolyzed to fluoroazaalkenes (90). 

Kyanalkine are 2,6-dialkyl-5-(alkyl less CH2)pyrimidin-4-amines thus kyanisobutin is 2,6-diisobutyl-5-isopropylpyrimidin-4-amine. 

Dialkylation of an amine or sulfonamide with a 1,3-dihalide provides a further route to azetidines <79CRV33l, 64HC( 19-2)88 5). Examples of this approach are the formation of N-tosylazetidine from tosylamide and l-bromo-3-chloropropane and the formation of N-alkylazetidinyl esters (36). The latter reaction works well except for R=Me the former provides a useful route to azetidine since the tosyl group can be removed by reductive methods. 

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