Monoalkyl quaternaries

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. 

Most work has been done with monoalkyl quaternaries, and the conclusions extended to the dialkyl cationic surfactants. This process is incorrect since the monoalkyl derivatives are much more water soluble than the corresponding dialkyl derivatives and they behave differently. Only a few studies have been carried out on DHTDMAC. They are discussed by Crutzen [102], A very different approach was that of Kunieda and Shinoda [88] and Laughlin and co-workers [89,103,104] who studied the phase diagram of dioctadecyldimethylammonium chloride as a model for DHTDMAC deposition. 

Furthermore, for some cationic surfactants, quantitative structure-activity relationships have been established for daphnids and fish. Increments used in the ECOSAR toxicity estimation software (Syracuse Research Center, freely available from the US Environmental Protection Agency as part of the software EPI Suite) are -0.13 and -0.37 for each carbon atom in monoalkyl quaternary ammonium surfactants in daphnids and fish, respectively. These increments are much smaller than the ones found here. Our increments for the n-alkyl chain in Rj position are more in accordance with increments for CH2 groups in n-octanol/water partitioning constant estimation procedures, which are, e.g., 0.66 and 0.49 in Hansch and Leo s method and Meylan and Howard s method, respectively [20]. This suggests that uptake into the cells is governed by lipophilicity, or maybe more exactly by membrane/water partitioning [21, 22]. 

Cocopropylenediamine Bis(3-aminopropyl) laurylamine Monoalkyl quaternary ammonium compounds Tetradecyltrimethylammonium bromide Hexadecyltrimethylammonium chloride Cocotrimethylammonium chloride Coco(fractionated)trimethylammonium chloride... 

Monoalkyl quaternaries, such as cetrimonium chloride, are cost-effective light conditioning additives, the dialkyl quaternaries, such as dicetyldimethylmonium... 

Simple monoalkyl quaternary ammonium salts have been shown to inhibit formation of gas hydrates of the type that block gas and oil pipelines and equipment. For the most part, in order to be effective the salts must have at least two C4-C6 alkyl groups on the quaternary head-group. Such head-groups appear to fit well within the nascent gas hydrate crystal and, by a mechanism that is not yet totally understood, inhibit further growth of such crystals. 

Even with a limited amount of the alkylating agent, the equilibria between protonated product and the neutral starting amine are sufficiently fast that a mixture of products may be obtained. For this reason, when monoalkylation of an amine is desired, the reaction is usually best carried out by reductive amination, a reaction that is discussed in Chapter 5. If complete alkylation to the quaternary salt is desired, use of excess alkylating agent and a base to neutralize the liberated acid normally results in complete reaction. 

The reaction of methylenesulphones with allyl halides in the presence of quaternary ammonium salts produces the 1-allyl derivatives [52], unlike the corresponding reaction in the absence of the catalyst in which the SN- product is formed (Scheme 6.5). In contrast, alkylation of resonance stabilized anions derived from allyl sulphones produces complex mixtures [51] (Scheme 6.6). Encumbered allyl sulphones (e.g. 2-methylprop-2-enyl sulphones) tend to give the normal monoalkyl-ated products. Methylene groups, which are activated by two benzenesulphonyl substituents, are readily monoalkylated hydride reduction leads to the dithioacetal and subsequent hydrolysis affords the aldehyde [61]. 

The quaternary ammonixim salt 73, thenium closylate, is an anthelmintic agent. Many substances of this general type are effective by interfering with nervous conduction, and thereby muscle tone, of intestinal worms. This allows their expulsion, not always in the dead state. The synthesis proceeds from 2-thienylamine (70) by monoalkylation with 2-phenoxyethyl bromide (71) to give secondary amine 72. 

The monoalkylated lactones 8 were isolated in > 90% yield. A second alkylation step with 8 (R = Et), under the same conditions and with the same alkylating agents, furnished the lactones 9 with a quaternary center in 95% yield. 

Table 5.4 Asymmetric monoalkylation of 21 under phase-transfer conditions catalyzed by chiral quaternary ammonium bromide (R,R)-le or (R)-16Aa.

This powerful quaternization method enabled the catalytic asymmetric synthesis of quaternary isoquinoline derivatives with 42 (R1 = Me) as a substrate. When 42 (R1 = Me) was treated with a,a -dibromo-o-xylene, CsOHH20 and (S,S)-le (1 mol%) in toluene at 0 °C, the transient monoalkylation product was rapidly produced, and subsequently transformed into the desired 44 (64%, 88% ee) during the work-up procedure. Catalytic asymmetric alkylation of 42 (R1 = Me) with functionalized benzyl bromide 45, followed by the sequential treatment with 1 M HC1 and then excess NaHC03, furnished the corresponding dihydroisoquinoline derivative 46 in 87% with 94% ee (Scheme 5.23) [25]. 

Both 1- and 2-tetralones have been exploited as intermediates to mor-phinans. An early report(25) described the isolation of the morphinan quaternary salt 29 in low yield from 2-tetralone. The monoalkylation product 28 has since proved elusive, with diakylation invariably occurring. Thus, the nature of the product claimed must be in doubt. 

This reaction is valuable in the preparation of certain monoalkyl aromatic hydrocarbons and aliphatic hydrocarbons having quaternary carbon atoms. The organometallic reagents most frequently used are Grignard reagents, zinc alkyls, and alkali-metal alkyls. 

The position of initial alkylation was established by protonation of the intermediate at the appropriate temperature. For the reaction of 2 with 1,3-dibromopropane, acidic hydrolysis at — 30 C resulted in monoalkylation, yielding the corresponding bromoolefin containing a quaternary center. On the other hand, the monoalkylated intermediates, derived from the treatment of 1,4-dibromobutane and 1,5-dibromopentane with 2, were protonated at room temperature, affording the corresponding noncyclized products. 

The dependence of deposition on degree of hydrophobicity indicates that van der Waals forces play an important role in deposition of quaternary ammonium conditioners [35], This conclusion is consistent with the entropy-driven deposition demonstrated by Ohbu et al. [37] for a monoalkyl quat and by Stapleton [38] for a protonated long-chain amine. 

Regiospecific alkylation of ketones. This salt converts trimethylsHyl enol ethers into quaternary ammonium enolates that undergo regiospecific monoalkylation. This method is especially useful for alkylation at the less substituted position of a cyclohexanone lithium enolates are more useful for alkylation at... 

Alkylation of tosylmethylisocyanide. Tosylmethylisocyanide (4, 514-516 5, 684-685) can be monoalkylated in high yield (75-95%) by primary alkyl halides (including alkyl chlorides and benzyl bromide) under phase-transfer conditions with either this quaternary salt or the less reactive benzyltriethyl-ammonium chloride. Yields are lower with secondary alkyl halides. With more reactive alkyl hahdes, the reaction is conducted at 0° to avoid dialkylation. 

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