Higher alkyl amines

The desired primary aminoalkylsilanes can be synthesized starting from the corresponding chloroalkyl precursors. The educts are reacted with excess ammonia (molar ratios 1 20 to 1 150) at pressures ranging from 30 to 200 bar and temperatures of 40 to 200 °C. The large ammonia excess is necessary to supress side reactions yielding higher alkylated amines (Eq. 1). 

Ethoxylation of alkyl amine ethoxylates is an economical route to obtain the variety of properties required by numerous and sometimes smaH-volume industrial uses of cationic surfactants. Commercial amine ethoxylates shown in Tables 27 and 28 are derived from linear alkyl amines, ahphatic /-alkyl amines, and rosin (dehydroabietyl) amines. Despite the variety of chemical stmctures, the amine ethoxylates tend to have similar properties. In general, they are yellow or amber Hquids or yellowish low melting soHds. Specific gravity at room temperature ranges from 0.9 to 1.15, and they are soluble in acidic media. Higher ethoxylation promotes solubiUty in neutral and alkaline media. The lower ethoxylates form insoluble salts with fatty acids and other anionic surfactants. Salts of higher ethoxylates are soluble, however. Oil solubiUty decreases with increasing ethylene oxide content but many ethoxylates with a fairly even hydrophilic—hydrophobic balance show appreciable oil solubiUty and are used as solutes in the oil phase. 

The reaction of higher alkyl chlorides with tin metal at 235°C is not practical because of the thermal decomposition which occurs before the products can be removed from the reaction zone. The reaction temperature necessary for the formation of dimethyl tin dichloride can be lowered considerably by the use of certain catalysts. Quaternary ammonium and phosphonium iodides allow the reaction to proceed in good yield at 150—160°C (109). An improvement in the process involves the use of amine—stannic chloride complexes or mixtures of stannic chloride and a quaternary ammonium or phosphonium compound (110). Use of these catalysts is claimed to yield dimethyl tin dichloride containing less than 0.1 wt % trimethyl tin chloride. Catalyzed direct reactions under pressure are used commercially to manufacture dimethyl tin dichloride. 

Reaction of alkyl halides 1 with hexamethylenetetramine 2 (trivial name urotropine) followed by a hydrolysis step, leads to formation of primary amines 3 free of higher substituted amines. This method is called the Delepine reaction, a comparable method is the Gabriel synthesis. 

Product composition can be controlled to a considerable extent by the molar ratio of reactants alkylation tends to become more extensive as the molar ratio of carbonyl to amine increases. Product distribution is influenced also by the catalyst and by steric hindrance with the amount of higher alkylate formed being inversely proportional to the steric hindrance in the neighborhood of the function (60 2). Cyclic ketones tend to alkylate ammonia or amines to a further extent than do linear ketones of comparable carbon number 36). 

Alkyl halides undergo Sn2 reactions with a variety of nucleophiles, e.g. metal hydroxides (NaOH or KOH), metal alkoxides (NaOR or KOR) or metal cyanides (NaCN or KCN), to produce alcohols, ethers or nitriles, respectively. They react with metal amides (NaNH2) or NH3, 1° amines and 2° amines to give 1°, 2° or 3° amines, respectively. Alkyl halides react with metal acetylides (R C=CNa), metal azides (NaN3) and metal carboxylate (R C02Na) to produce internal alkynes, azides and esters, respectively. Most of these transformations are limited to primary alkyl halides (see Section 5.5.2). Higher alkyl halides tend to react via elimination. 

Another approach in the study of the mechanism and synthetic applications of bromination of alkenes and alkynes involves the use of crystalline bromine-amine complexes such as pyridine hydrobromide perbromide (PyHBts), pyridine dibromide (PyBn), and tetrabutylammonium tribromide (BiMNBn) which show stereochemical differences and improved selectivities for addition to alkenes and alkynes compared to Bn itself.81 The improved selectivity of bromination by PyHBn forms the basis for a synthetically useful procedure for selective monoprotection of the higher alkylated double bond in dienes by bromination (Scheme 42).80 The less-alkylated double bonds in dienes can be selectively monoprotected by tetrabromination followed by monodeprotection at the higher alkylated double bond by controlled-potential electrolysis (the reduction potential of vicinal dibromides is shifted to more anodic values with increasing alkylation Scheme 42).80 The question of which diastereotopic face in chiral allylic alcohols reacts with bromine has been probed by Midland and Halterman as part of a stereoselective synthesis of bromo epoxides (Scheme 43).82... 

Mylroie et al. studied the optimal conditions for reductive alkylation of A-(4-ni-trophenyl)acetamide with ketones using Pt-C and sulfided Pt-C.49 In general, the sulfided catalyst was superior in the yield of the alkylated amines. There was no indication of either reduction of the ketone or saturation of the ring. With a higher loading of ketone (6 equiv) at 100°C and 6.9 MPa H2 in ethanol, excellent yields (98.5-99%) of the alkylated amines were obtained from the reaction of acetone (eq. 6.24), cyclohexanone, 2-pentanone, and 3-pentanone with A-(4-ni-trophenyl)acetamide. 

For alkyl amines, a direct correlation between the steric bulk at the a-carbon and the yield of the reaction was found amines attached to a secondary carbon gave higher yields than amines connected to a tertiary carbon, while amines connected to a quaternary carbon led only to the formation of an amide-carboxylic acid intermediate, rather than the corresponding imide. In the case of amino acids whose ot-carbons are tertiary, a lower temperature was surprisingly required for high NMI selectivity in the first step (40 °C instead of 75 °C). This was explained by the presence of the COOR group, which assists in the collapse of the tetrahedral intermediate precursor to the imide formation. The amino acid derived NMIs were obtained as a mixture of open and closed forms due to the addition of triethylamine in the reaction. At high temperatures this promotes the formation of... 

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