Stable quats

A third and more recent example of where readily biodegradable surfactants have replaced surfactants that are more long-lived in the environment is the taking over of the market for textile softener surfactants by the ester quats from the stable quats. This transition is still in progress today but for several years the big soapers all base their softener formulations for the US and Western Europe markets on ester quats instead of traditional, stable quats. The change from stable quats to ester quats is probably the best example of the concept of introducing a cleavable bond in a given surfactant structure because the two types of products are very similar in structure and physical chemical charac-... 

Fig.1 A Stable quat (top) and three ester quats of the type that is used for textile softening...

The three transitions mentioned above, replacement of branched alkylben-zene sulfonates by linear alkylbenzene sulfonates, replacement of alkylphenol ethoxylates by alcohol ethoxylates and substitution of ester quats for stable quats are all driven by environmental concerns. Rate of biodegradation and aquatic toxicity are the major parameters taken into account, and, in order to pass the regulations that the European Union has adopted, a surfactant must pass the criteria of showing ... 

It is common practice to put the experimentally obtained values for biodegradation and aquatic toxicity into a kind of matrix, as is illustrated by Fig. 2. The shaded areas in the matrix are the approved areas . Out of the six product types discussed above linear alkylbenzene sulfonates, alcohol ethoxylates, and ester quats lie within the shaded areas, while branched alkylbenzene sulfonates, alkylphenol ethoxylates and stable quats do not. 

During the last decade, the dialkylester quats have to a large extent replaced the stable dialkyl quats as rinse-cycle softeners, which is the single largest application for quaternary ammonium compounds. The switch from stable dialkyl quats to dialkylester quats may represent the most dramatic change of product type in the history of surfactants, and is entirely environment-driven. Unlike stable quats, ester quats show excellent values for biodegradability and aquatic toxicity. Ester quats have also fully or partially replaced traditional quats in other applications of cationics, such as hair care products and various industrial formulations. 

Selection of appropriate quaternary ammonium catalysts is limited by their stability in the reaction medium. The cellulose pretreatment requires heating in strong caustic solutions up to 120 most tetraalkyl ammonium salts undergo Hoffman degradation under these conditions. We have found two relatively stable quat salts, tetramethylammonium chloride and N,N-dimethylmorpholinium... 

Obviously, higher temperatures can lead to faster decomposition. The use of quats above temperatures of 100 to 120 "C usually results in partial or total decomposition. Recently, quats that are stable up to about 200 C have been prepared (Sharma, 1997 Dehmiow, 1993). Figure 3.60 shows two examples. Only the iminium chloride catalyst is also very stable in the presence of hot concentrated NaOH (Dehmiow and Knufinke, 1989). 

Harmon RS, Schwarcz HP, O Neil JR (1979) D/H ratios in speleothem fluid inclusions A grride to variatiorrs in the isotopic compositions of meteoric precipitation Earth Planet Sci Lett 42 254-266 Harmon RS, Thompson P, Schwarcz HP, Ford DC (1975a) Late Pleistocene paleoclimates of North America as irrferred from stable isotope studies of speleothems. Quat Res 9 54-70 Harmon RS, Thompson P, Schwarcz HP, Ford DC (1975b) Uranium-series dating of speleothems. Nat Speleolo cal Soc Bull 37 21-33... 

Esterquats, quaternary carboxyalkyl ammonium compounds, have been developed as substitutes for the quats, especially DTDMACs which are applied as softeners in household products because they are resistant to degradation [42] and toxic [43,44]. Today, the esterquats are preferentially used (see Fig. 2.12.1(b)). As previously noted, the detection of all types of esterquats in environmental samples is difficult because of their tendency to adsorb at surfaces. Even in the inflows of wastewater treatment plants (WWTP) it is extremely difficult to find these compounds, which are reduced in toxicity [45] compared with the DTDMACs. One reason is that these carboxyalkyl ammonium compounds are not very stable in the environment. A second reason is that these compounds are not stable during the ionisation process. 

In attempts to impart physicochemical properties of a "quat" synthesized VPI-5 to an "amine" synthesized VPI-5, we conducted several exploratory syntheses using mixtures of amines and quats. Some of our results are illustrated in Table 1. The quaternary ammonium hydroxides were added just after the addition of the amine using the synthesis procedure outlined above. First, it is apparent that a small amount of a "quat" can influence the synthesis of VPI-5. When using DPA, 1/80 or 1/60 TMA extends the time that VPI-5 is stable in the mother liquor. Also, 1/40 TMA inhibits the formation of VPI-5. Quats other than TMA appear to perform the same tasks as TMA. Since TMAOH is inexpensive, we continued to explore the use of TMAOH with other amines. The data in Table 1 show that TMAOH can be used with amines other than DPA to crystallize VPI-5. To date TIPOA appears to give the best VPI-5 product which fortunately also is obtained in high yield. 

SDS was an exception. Among the traditional surfactant work-horses, including anionics (such as alkylbenzene sulfonates and alkyl sulfates), nonionics (such as alcohol ethoxylates and alkylphenol ethoxylates), and cationics (such as alkyl quats and dialkyl quats), only alkyl sulfates are not chemically stable under normal conditions. 

Gorbarenko S. A. (1996) Stable isotope and lithologic evidence of late-Glacial and Holocene oceanography of the northwestern Pacific and its marginal seas. Quat. Res. 46, 230-250. 

Desmarchelier, J.M., Goede, A., Ayliffe, L.K., McCulloch, M.T., and Moriarty, K., 2000, Stable isotope record and its palaeoenvironmental interpretation for a late Middle Pleistocene speleothem from Victoria Fossil Cave, Naracoorte, South Australia, Quat. Set Rev. 19 763-774. 

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Harmon, R.S., Thompson, P., Schwarcz, H.P. and Ford, D.C., 1978b, Late Pleistocene paleoclimates of North America as inferred from stable isotope studies of speleothems, Quat. Res. 9 54-70. 

Vesica, P.L., Tuccimei, P., Turi, B., Fomos,J.J., Gines,A. and Gines, J., 2000, Late Pleistocene paleoclimates and sea-level change in the Mediterranean as inferred from stable isotope and U-series studies of overgrowths on speleothems, Mallorca, Spain, Quat. Sci. Rev. 19 865-879. 

Bar-Matthews, M., Ayalon, and Kaufman, A., 1997, Late Quaternary paleoclimate in the eastern Mediterranean region from stable isotope analysis of speleothems at Soreq Cave, Israel, Quat. Res. 47 155-168. 

Holmgren, K., Karlen, W., and Shaw, P. A., 1995, Paleoclimatic significance of the stable isotopic composition and petrology of a Late Pleistocene stalagmite from Botswana, Quat. Res. 43 320-328. 

So far, much research has gone into finding new synthetic routes, new products and novel selective syntheses, and in the analysis of important factors affecting yield and in some cases selectivity. However, other practical constraints relevant to process development for industrial-scale synthesis have to be tackled. For example, new insights are needed to develop cost-effective, stable, and selective PT catalysts (especially effective immobilized triphase catalysts). Other relevant factors include the recovery and recycle of the PT catalyst, catalyst decomposition, environmental issues such as catalyst toxicity, and ease of product recovery. Catalyst costs are not very high when quats are used, as against the more expensive crown ethers or cryptands. In most cases, the overall process is more than cost-effective since PTC allows the use of cheap alternative raw materials, prevents the use of costly dipolar solvents, is less energy intensive (due to lower temperatures) than alternative methods, alleviates the need... 

In principle, any (w-functionalized alkylating agent could be used for the quat-ernization of a tertiary amine or phosphine, provided that the alkylation reaction is chemosdective and the alkylating agent stable under the alkylation conditions. Several examples, selected for their potential to give further functionalized ionic liquids and therefore serve as soluble supports, are reported below including ionic... 

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Valero-Garces, B. L., K. R. Laird, S. C. Fritz, K. Kelts, E. Ito E. C. Grimm, 1997. Holocene climate in the Northern Great Plains inferred from sediment stratigraphy, stable isotopes, carbonate geochemistry, diatoms, and pollen at Moon Lake, North Dakota. Quat. Res. 48 359-369. 

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Uses Dispersant, dewatering agent, emulsifier, flocculant, softener (as quat) for oil fields, metalworking, textiles, paper, lubricants, paints, inks, agric., maintenance chems. bitumen emulsifier Features Thermally stable acid stable substantive to metal, glass and paint... 

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