Of ethoxy group

The number of ethoxy groups (CH3CH2O-) in an organic compound can be determined by the following sequence of reactions... 

The analysis of alcohol sulfates has been known for many years. Alcohol ether sulfates are analyzed in a similar way but the presence of ethoxy groups makes the complete procedure longer and more complex. 

An analysis of alcohol and alcohol ether sulfates should determine the anionic active matter, the unsulfated matter, the inorganic sulfate content, the chloride content, and water. Other more precise analysis must determine the alkyl chain distribution of the alcohol and in the case of alcohol ether sulfates the number of ethoxy groups and its distribution, as well as other more specialized determinations, such as the content of 1,4-dioxane and other impurities. 

Fig. 2.6.3. Mixed-mode HPLC-ESI-MS summed ion chromatogram of a sediment extract (32-36 cm depth core slice) showing resolution of NPEOs and NPs. Numbered peaks correspond to NPEOs and [13CeJNPEOs with the indicated number of ethoxy groups (0 = NP, [13C6]NP 1 = NPEOi, [13C6]NPEOi, etc.). Peaks A and B are the internal standards, re-NP and re-NPE03, respectively. (Note the discontinuity at retention time 25.8 min, corresponding to the shift in MS polarity from positive to negative ion mode.)...

Scrambling of ethoxy groups between sulfur atoms in close proximity has been observed for l-(J3-mcthylcthoxysulfonio)-9-(mcthyltliio)dibeiizothiophene (55) and some analogous compounds.55... 

The 13C spectrum (fig. 9.6 b) indicates a total loss of ethoxy groups as no peaks are observed at 57.6 ppm (-OCH2-) and 15.9 ppm (-OCHjCHj). The three observed peaks have been assigned19 to the propyl carbons (aCH=9.5 ppm, /3CH=26.3 ppm, 7CH=43.3 ppm). The 13C shift value of the CH is an indication of the stability of the aminosilane coating on the silica surface. Caravajal22 has shown that an increase in the APTS coating stability shifts the aCH peak to higher shift value (APTS solution aCH=7.9 ppm). The observed peak position of the aCH (9.5 ppm) indicates the covalent attachment of the silane molecules to the silica surface. 

The effect of surface water and air humidity on the hydrolysis of APTS molecules adsorbed on the silica surface may be characterized as follows. Short time exposures to humid air cause partial hydrolysis of the modified layer. Extensive hydrolysis is only caused by surface adsorbed water. Hydrolyzed aminosilane molecules at the surface condense to form an aminopropylpolysiloxane layer. Only when all three modification stages (pretreating, loading, curing) are performed in completely dry conditions, hydrolysis of ethoxy groups can be prevented. The structures formed under the various modification conditions are summarized in figure 9.5. 

However, using a hydrated silica as a substrate results in the complete disappearance of the 13C resonance of ethoxy groups, indicating that all alkoxygroups have participated in the reaction. 

Non-ionic surfactants are neither positively nor negatively charged but instead they have several oxygen atoms at the head end of the molecule, generally in the form of a series of ->ethoxy groups.711 They produce less foam than anionic surfactants and are used in low temperature laundry detergents because they work well even at 30 °C. 

In the desorption experiments changes in film characteristics are assumed to include the displacement of physically adsorbed or entangled molecules, the hydrolysis of ethoxy groups and possibly the hydrolysis of some =Si—O—Si= linkages. 

Apart from the addition reaction to electrophilic olefins, the / -carbon atom of 1,1-enediamines can also substitute a,/ -unsaturated compounds carrying a leaving group. Schafer and Gewald129 have shown that 141 and 142 react with 143 to give product 144 in moderate to good yields (equation 54). Ketene dithioacetals derived from an alkyl cyanoacetate and malononitrile behave similarly to 143130. When imine 145 is employed, the reaction results in the formation of 146 (equation 55)129. Apparently displacement of ethoxy group and cyclocondensation by attack on the nitrile moiety are the key steps in the reaction. 

Starting with three pounds each of the zinc diethyl and ethyl silicate, Ladenburg prepared all of the ethylethoxysilanes and described their properties. He also was able to show that the reaction was not a simple reduction of ethoxy groups to ethyl groups by the action of sodium, for methyl silicate and zinc ethyl gave e %imethoxysilanes. It is probable that the sodium reacted first with the zinc alkyl, as proposed by Ladenburg,... 

Figure 2. Effect of number of ethoxy groups on foam volume produced by AE 1215-n surfactants.

Summary Hydrolytic polycondensation of octyltriethoxysilane (OTES) was studied by H and Si NMR spectroscopy, GLC, and Fischer titration. Hydrolysis rate in terms of ethoxy groups was found to exceed polycondensation rate during the reaction in ethyl alcohol with hydrochloric acid as a catalyst. The molecular mass of hydrolytic polycondensation oligomers reaches a maximum value at molar ratio water/OTES = 1.5. 

Thus, for example, for molar ratio of water/OTES = 0.8, water coiwersion amounts to 94% during the first 15 min and 97.9% in 24 h. At the same time, according to H NMR data, water consumption on cleavage of ethoxy groups amounts to 70% during the first 15 min and 97.9% in 24 h. This testifies to the fact that the hydrolytic reaction according to Eq.l proceeds faster than polycondensation reactions according to Eqs. 2 and 3. 

A combination of SLS and DLS methods was used to investigate the behavior of nonionic micellar solutions in the vicinity of their cloud point. It had been known for many years that at a high temperature the micellar solutions of polyoxyethylene-alkyl ether surfactants (QEOm) separate into two isotropic phases. The solutions become opalescent with the approach of the cloud point, and several different explanations of this phenomenon were proposed. Corti and Degiorgio measured the temperature dependence of D pp and (Ig), and found that they can be described as a result of critical phase separation, connected with intermicellar attraction and long-range fluctuations in the local micellar concentration. Far from the cloud point, the micelles of nonionic surfactants with a large number of ethoxy-groups (m 30) may behave as hard spheres. ... 

As was mentioned this scheme seems to be valid for HZSM-5 zeolites. In our opinion for SAPO-5 which exhibit weaker acidity than HZSM-5 this mechanism is stopped at the stage of ethoxy groups formation and further oligomerization does not take place. It is in good agreonent with the observed... 

As indicated earlier, those materials that are skin irritants are oftentimes eye irritants too, although there is not a perfect correlation between the two tests. The data of Table 5-23 show that adding up to 12 ethylene oxide units to an alcohol sulfate detergent creates sodium laureth-12 sulfate, which produces virtually no skin irritation. However, adding only 1 to 3 ethylene oxide units creates sodium laureth-(l-3) sulfate, a surfactant that is more irritating to eyes. Further increasing the number of ethoxy groups beyond 3 to 12 decreases both eye and skin irritation. 

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