Cyclohexanone content

Similar behavior was observed in the relationship between membrane thickness and cyclohexanone content as shown in Figure... 

The membrane thickness comes to a minimum where permeation has the lowest value. Scanning electron microscope studies on membrane substrate structure revealed that a change from a finely pored sponge structure to a coarsely pored finger structure occurs at the point where the membrane thickness turns to go up with increase in cyclohexanone content as already shown in Figure 6. 

As shown in Figure 5, the very steep drop of water flux corresponding to the rise of cyclohexanone content higher than 0.6 was caused either by decrease in water or by Increase in cyclohexanone. In order to see which of these two components governs this sharp drop of water flux, numerical data on these descending lines are summarized in Table IV. 

Figure 5. Membrane performance vs. cyclohexanone content in the additive solution. Numbers attached to each curve indicate the amount of additive solutions in weight percent of dope.

Figure 6. Membrane thickness vs. cyclohexanone content in the additive solution...

Figure 7. Membrane cross-section for cyclohexanone content of 32 wt % of additive solution...

Solubility. One of PVP s more outstanding attributes is its solubility in both water and a variety of organic solvents. PVP is soluble in alcohols, acids, ethyl lactate, chlorinated hydrocarbons, amines, glycols, lactams, and nitroparaffins. SolubiUty means a minimum of 10 wt % PVP dissolves at room temperature (moisture content of PVP can influence solubiUty). PVP is insoluble in hydrocarbons, ethers, ethyl acetate, j -butyl-4-acetate, 2-butanone, acetone, cyclohexanone, and chlorobenzene. Both solvent polarity and H-bonding strongly influence solubiUty (77). 

In a 2-1. three-necked flask (Note 1), fitted with a dropping funnel, condenser (equipped with a Drierite tube), and efficient stirrer driven by a powerful motor, is placed a mixture of 600 ml. of benzene, 48 g. (0.85 mole) of potassium hydroxide (Note 2), and 76.4 g. of powdered calcium carbide (Note 3). While this mixture is being stirred vigorously, 85 g. (0.87 mole) of cyclohexanone is added over a period of 0.5-1 hour. The mixture is dark gray and will become warm, but no external cooling is necessary. Stirring is continued, and within 24 hours the contents congeal (Note 4). This semisolid is allowed to stand for an additional 4 days (Note 5). 

Nitromethane is commercially available with the following specifications (by weight) purity, 98.0% min. total nitroparaffms, 99.0% min. acidity (as acetic acid), 0.1% max. and water, 0.1% max. Nitromethane can be made less sensitive to detonation by shock by the addition of compounds such as alcohols, hydrocarbons, esters and ketones. These desensitizers, with the minimum content by weight that must be present in the mixtures, are cyclohexanone (25%), 1,4-dioxane (35%), 1,2-butylene oxide (40%), methanol (45%), 2-nitropropane (47%), 1-nitropropane (48%) or methyl chloroform (50%) (Angus Chemical Co., 1998). 

To a 500 ml, three-necked, round-bottomed flask equipped with a Dean and Stark trap, condenser, and stirrer is added a mixture of 52.5 gm (0.60 mole) of morpholine, 49 gm (0.5 mole) of cyclohexanone, 100 ml of toluene, and 0.5 gm ofp-toluenesulfonic acid. The contents are refluxed for approximately 4 hr to remove the water of reaction. The product mixture is cooled and then distilled to afford 59 gm (71 %) of the enamine, b.p. 117°-120°C (10 mm), n 5 1.5122-1.5129. Yields of enamine have been reported to vary from 71 to 80%. 

Oxidation of Cyclohexane. The synthesis of cyclohexanol and cyclohexanone is the first step in the transformation of cyclohexane to adipic acid, an important compound in the manufacture of fibers and plastics. Cyclohexane is oxidized industrially by air in the liquid phase to a mixture of cyclohexanol and cyclohexanone.866 872-877 Cobalt salts (naphthenate, oleate, stearate) produce mainly cyclohexanone at about 100°C and 10 atm. The conversion is limited to about 10% to avoid further oxidation by controlling the oxygen content of the reaction mixture. Combined yields of cyclohexanol and cyclohexanone are about 60-70%. 

Preliminary data on the reactivity of these materials in a typical Knoevenagel reaction (cyclohexanone and ethyl cyanoacetate) indicates a general trend towards higher activity with increasing water content in the material preparation system. This is complicated by some irregularities in the data from the samples prepared from solvents with roughly comparable water ethanol volume ratios. While many systems have been described where the catalytic activity correlates with changes in textural properties[9], the trends in activity found in this study correlate best with an increase in framework mesopore diameter, and do not follow the... 

Effect of platinum content. Since a beneficial role of platinum deposited on titania had been reported for the photocatalytic oxidation of some organic compounds (refs 6, 7), several catalysts, from 0.5 to 10 wt % Pt with a constant particle size, were prepared and studied. The variations of the initial rate of formation of cyclohexanone as a function of Pt contents are shown in Fig. 2. There is not only no beneficial effect of Pt as mentioned in refs.(6, 7) but a... 

A much more efficient means of promoting the reaction is variation of the KOH content of the reaction mixture. This was convincingly shown for the conversion of cyclohexanone oxime to 4,5,6,7-tetrahydroindole (1) and its N-vinyl derivative in the reaction with acetylene in KOH/DMSO (Scheme 1) (81ZOR 1977). At a moderate temperature (100°C), an increase in the KOH content (up to an equimolar ratio to the oxime) enhances the yield of l-vinyl-4,5,6,7-tetrahydroindole (Table VI). Under more severe conditions (120°C) the alkali starts to accelerate side processes as a consequence of which an inverse dependence of the yield of l-vinyl-4,5,6,7-tetrahydroindole upon the content of base is observed (cf. Table VI). 

Measuring Methods. Chlorine content was determined by the oxygen flask method (2) on a polymer purified by precipitation from the solution in cyclohexanone. Thermal stability, as HC1 evolution, was determined according to ASTM method D-793-49, determining the quantity of HC1 evolved by the polymer maintained at 180 °C in a nitrogen atmosphere. From the slope of the straight line for the amount of HC1 evolved with time, the constant K for the dehydrochlorination rate (DHC) is deduced. 

The double bond of the enol form of 1,4-cyclohexanedione is not conjugated with the carbonyl group. Its enol content is expected to be similar to that of cyclohexanone. 

The characteristics of the water pool of reverse micelles has been explored by H, 23Na, 13C, 3IP-NMR spectroscopy. Since the initial association process in RMs is not totally understood, and because of the low CMC, aggregation studies from NMR are rather scarce. Direct determination of a CMC in the diethyl hexyl phosphate /water/benzene system (at Wo = 3.5) was possible because the chemical shift of 31P in phosphate groups is very sensitive to hydration effects. The structure and state of water in RMs and particularly at low water content has received considerable attention. The proton chemical shifts have been explored in AOT/water/heptane, methanol, chloroform, isooctane and cyclohexanone. The water behavior in small reverse micelles is close to that of the corresponding bulk ionic solution. Until now, the effect of a solute on micellar structure was not well... 

The reactions were carried out in 300 ml. stainless steel Whitey reaction vessels heated for 30 minutes in a constant temperature oil bath. The come-up time to reach the oil bath temperature was shortened by preheating for 10 minutes in a 70°C water bath. After heating, the vessels and contents were cooled rapidly to about 5°C. A 100 ml aliquot of each reacted sample was adjusted to pH 10 according to Tressl et al. (6) and extracted four times with 100 ml portions of methylene chloride. The extracts were combined and concentrated to approximately 5 ml. at ambient temperature. One ml of 0.30% v/v cyclohexanone in methylene chloride internal standard was added, the samples were brought to 10.0 ml and were then filtered through 0.5 p Teflon cartridge filters. 

Fig. 12. 3. Enol content of three representative /t-diketones (B-D) ten-million-fold increase as compared to cyclohexanone (A).

Figure 12.24 depicts the oxidation of a silyl enol ether A to give an a,/3-unsaturated ketone B. Mechanistically, three reactions must be distinguished. The first justifies why this reaction is introduced here. The silyl enol ether A is electrophilically substituted by palladium(II) chloride. The a-palladated cyclohexanone E is formed via the intermediary O-silylated oxocarbenium ion C and its parent compound D. The enol content of cyclohexanone, which is the origin of the silyl enol ether A, would have been too low to allow for a reaction with palladium(II) chloride. Once more, the synthetic equivalence of a silyl enol ether and a ketonic enol is the basis for success (Figure 12.24). 

The next section will explain in more detail the content of different levels. The approach will be applied throughout the whole book, although not in a repetitive manner. Actually, each case study will emphasize only generic conceptual elements. The case study regarding the manufacturing of cyclohexanone by phenol hydrogenation is a kind of leading example. Since the book focuses on technical aspects, there is no place for cost evaluation and profitability analysis. 

Deuterated Cyclohexenes. 1,3,3-Trideuterocyclohexene (5) was synthesized from cyclohexanone according to the method of Fahey and Monahan (27) except that diazabicyclononane (DBN) was used instead of potassium t-butoxide in the final step. 3,3,6,6-Tetradeuterocyclohexene (6) was obtained from Merck, Sharp, and Dohme (>98%-d4). The degree of deuteration of the labeled cyclohexenes was determined by converting them to the corresponding 1,2-dibromocyclohexanes by treatment with bromine in carbon tetrachloride. The deuterium content of these dibromocyclohexanes was determined conveniently by observing the M-bromine region of the mass spectrometry. 

---