Quaternary ammonium salts, alkylations with

Secondary amines, such as pyrrolidine, must be alkylated with care too polar a solvent leads to participation of a second nearby polymer-bound alkylant in the formation of a quaternary ammonium salt, along with the desired immobilized trialkyl amine. The exception, as seen above, is diisopropylamine, which refuses to displace tosylate even in the refluxing pure amine, or in hot dimethyl-formamide or other polar solvent, while metal diisopropylamide is notorious as a powerful non-nucleophilic base. However, carboxamide is not difficult to form from (carboxymethyl)polystyrene, again using toluenesulfonyl chloride as condensing agent this can then be reduced to (diisopropyl-ethylaminoethyl)polystyrene, which is of interest as a polymer-bound non-nucleophilic base. ... 

Amines can displace a halide or a derivative of an alcohol, such as the methanesulfonate or toluene-4-sulfonate, with the eventual formation of a quaternary ammonium salt. Reaction with ammonia may lead to mixtures, since the initial alkylation increases the basicity of the nitrogen, and hence the primary amine reacts more rapidly than ammonia. Further reaction, although enhanced by the increase in basicity, may be impeded by steric hindrance arising from the additional alkyl groups. 

Fine glass beads are made free-flowing by treating the surface with a mixture of aqueous colloidal silica and a long-chain alkyl quaternary ammonium salt along with isopropyl alcohol (611). 

Amines are powerful nucleophiles which react under neutral or slightly basic conditions with several electron-accepting carbon reagents. The reaction of alkyl halides with amines is useful for the preparation of tertiary amines or quaternary ammonium salts. The conversion of primary amines into secondary amines is usually not feasible since the secondary amine tends towards further alkylation. 

Even the tertiary amine competes with ammonia for the alkylating agent The product is a quaternary ammonium salt... 

Quantum (Section 13 1) The energy associated with a photon Quaternary ammonium salt (Section 22 1) Salt of the type R4N X The positively charged ion contains a nitrogen with a total of four organic substituents (any combination of alkyl and aryl groups)... 

Quaternary ammonium alkyl ethers are prepared similarly an alkaline starch is reacted with a quaternary ammonium salt containing a 3-chloto-2-hydtoxyptopyl or 2,3-epoxyptopyl radical. Alternatively, such derivatives can be prepared by simple quaternization of tertiary aminoalkyl ethers by reaction with methyl iodide. Sulfonium (107) and phosphonium (108) starch salts have also been prepared and investigated. Further work has explained the synthesis of diethyl aminoethyl starch (109) as well as the production of cationic starches from the reaction of alkaline starch with... 

The nitrogen of aHphatic and aromatic amines is alkylated rapidly by alkyl sulfates yielding the usual mixtures. Most tertiary amines and nitrogen heterocycles are converted to quaternary ammonium salts, unless the nitrogen is of very low basicity, eg, ia tn phenylamine. The position of dimethyl sulfate-produced methylation of several heterocycles with more than one heteroatom has been examined (22). Acyl cyanamides can be methylated (23). Metal cyanates are converted to methyl isocyanate or ethyl isocyanate ia high yields by heating the mixtures (24,25). 

An alkyl halide 1 reacts with hexamethylenetetramine 2 to the quaternary ammonium salt 4, which crystallizes from the reaction mixture ... 

Generally the desired substituted carbonyl compound 3 is obtained after hydrolytic workup under acidic conditions. With simple alkyl halides an irreversible A-alkylation may take place as a side-reaction to give a quaternary ammonium salt 7 ... 

Ammonia and other amines are good nucleophiles in SN2 reactions. As a result, the simplest method of alkylamine synthesis is by Sn2 alkylation of ammonia or an alkylamine with an alky) halide. If ammonia is used, a primary amine results if a primary amine is used, a secondary amine results and so on. Even tertiary amines react rapidly with alkyl halides to yield quaternary ammonium salts, R4N+ X-... 

We ve already studied the two most general reactions of amines—alkylation and acylation. As we saw earlier in this chapter, primary, secondary, and tertiary amines can be alkylated by reaction with a primary alkyl halide. Alkylations of primary and secondary amines are difficult to control and often give mixtures of products, but tertiary amines are cleanly alkylated to give quaternary ammonium salts. Primary and secondary (but not tertiary) amines can also be acylated by nucleophilic acyl substitution reaction with an acid chloride or an acid anhydride to yield an amide (Sections 21.4 and 21.5). Note that overacylation of the nitrogen does not occur because the amide product is much less nucleophilic and less reactive than the starting amine. 

Polymer-supported amino alcohols and quaternary ammonium salts catalyze the enan-tioselective addition of dialkylzinc reagents to aldehydes (Table 31). When the quaternary ammonium salt F is used in hexane, it is in the solid state, and it catalyzes the alkylation of benzaldehyde with diethylzinc in good chemical yield and moderate enantioselectivity. On the other hand, when a mixture of dimethylformamide and hexane is used as solvent, the ammonium salt is soluble and no enantioselectivity is observed21. 

The dialkylamino, especially the dimethylamino, group in a cyclopentenone of type 67 can be alkylated with methyl iodide to yield a quaternary ammonium salt. Upon treatment with a base, these quaternary ammonium salts undergo... 

Oxonium ions are excellent alkylating agents, and ethers can be conveniently prepared by treating them with alcohols or phenols. Quaternary ammonium salts can sometimes also be used. ... 

Tertiary aliphatic amines are also cleaved by HI, but useful products are seldom obtained. Tertiary amines can be cleaved by reaction with phenyl chloroformate R3N -h ClCOOPh —> RCl 4- R2NCOOPh. a-Chloroethyl chloroformate behaves similarly.Alkyl halides may be formed when quaternary ammonium salts are heated R4N+X" R3N -)- RX. ... 

Benzylic quaternary ammonium salts, when treated with alkali metal amides, undergo a rearrangement called the Sommelet-Hauser rearrangementSince the product is a benzylic tertiary amine, it can be further alkylated and the product again subjected to the rearrangement. This process can be continued around the ring until an ortho position is blocked. ... 

The higher solubility of several quaternary ammonium salts of glyphosate in polar aprotic organic solvents such as acetonitrile was discovered (2), which permitted their reaction in solution with various alkyl halides. For example, GLY(n-Bu4N)2H reacted with either o-xylylene dichloride or 1,5-dibromopentane to produce the interesting quaternary glyphosate derivatives 81 and 82, whose structures have been confirmed by x-ray analysis (2). 

Tertiary amines react with alkyl halides to form quaternary ammonium salts... 

The alkyl halide (ethyl bromide in the above equation) can react further with the primary amine produced to give a secondary amine and with that to form a tertiary amine and finally a quaternary ammonium salt. Quaternary ammonium hydroxides are very strong bases like sodium hydroxide. Tetramethylammonium hydroxide is a very important chemical used in the manufacture of semiconductors and other electronic industry products. 

Certain quaternary ammonium salts will alkylate [Co (DMG)2py] . The addition of PhCH2NMc3 I to a solution of the complex in methanol gives the PhCH2Co complex in 45% yield. The reaction works more slowly with dimethylpiperidinium iodide to give the CH3—Co complex 15). There is no alkylation with tertiary amines alone 164), but in the presence of equimolar amounts of dimethylacetylenedicarboxylate certain aliphatic tertiary amines can alkylate [Co (DMG)2py] in methanol solution. The reaction also produces the enamine derivative of a maleic ester, and the mechanism appears to involve addition of the amine to the triple bond to form an ammonium salt, which can then attack the Co(I) derivative (75). 

Quaternary ammonium salt catalysts based on diff mt alkyl cations such as tetrapropylammonium (TPA, tetrabutylammonium (TBA, tetrahex5dammonium (THA ), tetraoctylammonium (TOA, tetradodecylammonium (TDodA, and those with different anions such as Q, Bf, and f were used. 

In the synthesis of DMC fiom the transesterification of EC and methanol, quaternary ammonium salt catalysts showed good catalytic activity. The main byproduct was ethylene glycol. The quaternary salt with the cation of bulkier alkyl chain laigth and witii more nucleophilic anion showed better reactivity. Hi temperature and large amount of catalyst increased the conversion of EC. The EC conversion and DMC selectivity increased as the pressure of CO2 increased from 250 to 350 psig. 

A thio-substituted, quaternary ammonium salt can be synthesized by the Michael addition of an alkyl thiol to acrylamide in the presence of benzyl trimethyl ammonium hydroxide as a catalyst [793-795]. The reaction leads to the crystallization of the adducts in essentially quantitative yield. Reduction of the amides by lithium aluminum hydride in tetrahydrofuran solution produces the desired amines, which are converted to desired halide by reaction of the methyl iodide with the amines. The inhibitor is useful in controlling corrosion such as that caused by CO2 and H2S. 

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