Sensing acetone

Crown-6 phase-transferred potassium cyanide adds, in either benzene or acetonitrile to several o ,i5-unsaturated ketones in the Michael sense. Acetone cyanohydrin serves as a proton source and cyanide carrier. This reaction is described in section 7.8 and equation 7.12. 

Acetone can be handled safely if common sense precautions are taken. It should be used in a weU-ventilated area, and because of its low flash point, ignition sources should be absent. Flame will travel from an ignition source along vapor flows on floors or bench tops to the point of use. Sinks should be rinsed with water while acetone is being used to clean glassware, to prevent the accumulation of vapors. If prolonged or repeated skin contact with acetone could occur, impermeable protective equipment such as gloves and aprons should be worn. 

These effects can be attributed mainly to the inductive nature of the chlorine atoms, which reduces the electron density at position 4 and increases polarization of the 3,4-double bond. The dual reactivity of the chloropteridines has been further confirmed by the preparation of new adducts and substitution products. The addition reaction competes successfully, in a preparative sense, with the substitution reaction, if the latter is slowed down by a low temperature and a non-polar solvent. Compounds (12) and (13) react with dry ammonia in benzene at 5 °C to yield the 3,4-adducts (IS), which were shown by IR spectroscopy to contain little or none of the corresponding substitution product. The adducts decompose slowly in air and almost instantaneously in water or ethanol to give the original chloropteridine and ammonia. Certain other amines behave similarly, forming adducts which can be stored for a few days at -20 °C. Treatment of (12) and (13) in acetone with hydrogen sulfide or toluene-a-thiol gives adducts of the same type. 

There has been a conventional sense that the PVAc latexes prepared in the presence of PVA as a protective colloid contain the graft copolymer of PVA and PVAc, so that PVAc particles in the dried latex film are not extracted at a high ratio with solvents. In this Chapter, it has been defined without an influence by the usual sense that the porous PVA-PVAc composite can be prepared from the PVAc latex film with acetone extraction. The porous film consists of the spherical cells of PVA... 

Smooth and uniform polymer surface after vacuum plays a key role to ensure good OFRR sensing performance. We have observed in experiments that toluene after vacuum is prone to leave a number of cavities of a few micrometers in diameter on the surface. These cavities will induce additional scattering loss for the WGMs in the OFRR, which greatly degrade the g-factor, and hence the detection limit of the OFRR vapor sensor. Moreover, these small cavities have different adsorption characteristics compared to smooth polymer surface. Vapor molecules may be retained for a longer time at the cavity, which increases the response time and recovery time. Acetone and methanol are found to be better candidates for solvents because they usually leave uniform and smooth surface after vacuum. 

The substance does not form saturated solutions in a single solvent, hence it has no limits of solubility in the usual sense of this term as applied to crystalline bodies. A solution resembling in its properties a saturated one can be prepared by means of a binary solvent, where a liquid immiscible with nitrocellulose is one of the two components (e.g. acetone and water). 

Figure II. C Is ESCA spectra for three reworked wafers. Note that the best results are observed for the acetone stripped wafer in the sense that it is ready to be recoated without silane reprinting.

Interestingly, the analytes of smaller sizes than that of the functional monomer used for MIP preparation were determined based on the MIP-PZ sensing. For instance, acetaldehyde was determined by using the methacrylate functional monomer for MIP preparation [154]. The fabricated MIP-PZ chemosensor was 11-fold more selective for acetaldehyde than for acetone. 

A typical example of similis similibus solvuntur is the mixture of acetone and dimethyl ether (see Fig. 6.6). The cr-profiles of both solvents are very similar. Both are asymmetric in the same sense, and hence they do not feel very well in themselves, nor in the mixture. However, due to the entropy gain of the mixing process... 

In a consumer sense, propanone is the most familiar ketone its common name is acetone. The flammability and odor associated with acetone are properties that are common among ketones. They are also generally good solvents—that is often their industrial purpose. 

The viscosities of many binary liquid systems display minima as functions of composition at constant temperature, so that negative values of D are also possible. Yajnik and his coworkers (265 ) long ago observed that very frequently an extremum in the isothermal vapor pressure-composition curve is accompanied by an extremum of the opposite sense in the viscosity-concentration curve. Data are apparently not available for solutions of very low-molecular-weight paraffins in carbon tetrachloride, but minima are found for the viscosities of solutions of CC14 with ethyl iodide, ethyl acetate and acetone, so that a minimum appears quite probable for mixtures of small aliphatic hydrocarbons with carbon tetrachloride. If this were true, the downward trend of the Meyer-Van der Wyk data on C17—C31 paraffins, earlier discussed in connection with the polyethylene plots of Fig. 14, would be understood. It will be recognized that such a trend is also precisely what is to be expected from the draining effect of the hydrodynamic theories of Debye and Bueche (79), Brinkman (45 ) and Kirkwood and Riseman (139). However, the absence of such a trend in the case of polyethylene... 

Figure 12.18 is drawn for a species that shows positive deviations from ideality in the sense of the Lewis/ Randall rule. Negative deviations from ideality are also common, and in this case the /j-vs.-x, curve lies below the Lewis/Randall line. In Fig. 12.19 we show the composition dependence of the fugacity of acetone in two different binary solutions at 50°C. When the second component is methanol, acetone shows positive deviations from ideality. On the other hand, when the second component is chloroform, acetone shows negative deviations from ideality. The fugacity of pure acetone f—<— is of course the same regardless of the second component. However, Henry s constants, represented by the slopes of the two dotted lines, are very different for the two cases. 

Luo et al. have fabricated a conductive polyurethane/MWNT composite thin film with a selective vapor-induced sensing performance through in-situ dispersion polymerization (120). This kind of thin films yielded higher responsivity to some solvent vapors like benzene, toluene, acetone and chloroform than others such as carbon tetrachloride, cyclohexane, methanol and formaldehyde. 

Perhaps plans have not heen formulated in several cases, or results disseminated. The avenues of research that the identification of a natural product may open are many, so that in the true sense these compounds may be considered allelochemic (J )as opposed to strictly allelopathic. For example, the discovery of a novel biologically active natural product logically presupposes that the metabolic pathway will eventually he elucidated, that possible synthesis, or partial synthesis may be attempted, that homologs and analogs will be described and that other areas may be considered for eventual employment of these materials, not only in more obvious uses such as pesticides, hut also medicinal and non-biological areas. An example of a non-biological use is that of orlandin ( ) which is denatured in acetone to produce an acid and base resistant product which is ceramic-like and is not soluble in organic solvents. 

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