Ethanolic solution

Water at 20°C rests on solid naphthalene with a contact angle of 90°, while a water-ethanol solution of surface tension 3S dyn/cm shows an angle of 30°. Calculate (a) the work of adhesion of water to naphthalene, (b) the criticd surface tension of naphthalene, and (c) y for naphthalene. 

Figrue BE 16.20 shows spectra of DQ m a solution of TXlOO, a neutral surfactant, as a function of delay time. The spectra are qualitatively similar to those obtained in ethanol solution. At early delay times, the polarization is largely TM while RPM increases at later delay times. The early TM indicates that the reaction involves ZnTPPS triplets while the A/E RPM at later delay times is produced by triplet excited-state electron transfer. Calculation of relaxation times from spectral data indicates that in this case the ZnTPPS porphyrin molecules are in the micelle, although some may also be in the hydrophobic mantle of the micelle. Furtlier,... 

When the solution has been boiling for hours, remove A, cool the contents, and then pour the ethanolic solution of the ester into a separating-funnel containing about 200 ml. of water, finally rinsing out the flask with a few ml. of water which are also doured into the funnel. Since the pensity of ethyl benzoate is only... 

If an ethanolic solution of picric acid is similarly added to one of aniline, no precipitation occurs, owing to the high solubility of aniline picrate in ethanol. If, however, a cold aqueous solution of aniline hydrochloride is added to a similar solution of sodium picrate and the mixture shaken, yellow crystals of aniline picrate, m.p. 165 , soon separate. 

In absolute ethanol solution, the ethyl ether and the corresponding hydrocarbon are formed, the latter by reduction of the diazonium compound by the ethanol, which is itself oxidised to acetaldehyde ... 

When an ethanolic solution containing both acetone and two equivalents of benzaldehyde is made alkaline with sodium hydroxide, rapid condensation occurs with the formation of dibenzal-acetone, or dibenzylidene-acetone. This... 

The Mannich Reaction involves the condensation of formaldehyde with ammonia or a primary or secondary amine and with a third compound containing a reactive methylene group these compounds are most frequently those in which the methylene group is activated by a neighbouring keto group. Thus when acetophenone is boiled in ethanolic solution with paraformaldehyde and dimethylamine hydrochloride, condensation occurs readily with the formation of... 

Mono and Di-iubstitution Derivatives. The enolic sodium derivative of ethyl acetoacetate (E) is prepared by mixing ethanolic solutions of the ester and of sodium ethoxide. It should not be prepared by the direct action of metallic sodium on the ester, as the reaction is slow and the nascent hydrogen evolved reduces some of the ester to ethyl p4iydroxy- butyrate, CH3CH(OH)CHjCOOEt. 

Substitution Derivatives of Ethyl Malonate, Ethyl malonate resembles ethyl acetoacetate in that it gives rise to mono- and di-substituted derivatives in precisely similar circumstances. Thus when ethanolic solutions of ethyl malonate and of sodium ethoxide are mixed, the sodium derivative (A) of the enol form is produced in solution. On boiling this solution with an alkyl halide, e.g, methyl iodide, the methyl derivative (B) of the keto form is obtained. When this is treated again in ethanolic solution with sodium ethoxide, the... 

When an ethanolic solution of the sodium derivative of ethyl malonate is. shaken with a solution of iodine, the latter withdraws the sodium, and the ethyl malonate residues link together in pairs to give the tetra-ethyl ester of... 

The Dimedone (V) in ethanolic solution reacts rapidly with formaldehyde to give methylene-dimedone (VI) which. 

If cold saturated ethanolic solutions of the recrystallised tetrahydrocarbazole and of picric acid are mixed and stirred, the chocolate-brown picrate of the carbazole slowly crystallises. After it has been filtered off at the pump, washed with a small quantity of ethanol, and dried, it has m.p. 145-146°. 

Amino-4 -methylthiazole slowly decomposes on storage to a red viscous mass. It can be stored as the nitrate, which is readily deposited as pink crystals when dilute nitric acid is added to a cold ethanolic solution of the thiazole. The nitrate can be recrystallised from ethanol, although a faint pink colour persists. Alternatively, water can be added dropwise to a boiling suspension of the nitrate in acetone until the solution is just clear charcoal is now added and the solution, when boiled for a short time, filtered and cooled, deposits the colourless crystalline nitrate, m.p. 192-194° (immersed at 185°). The thiazole can be regenerated by decomposing the nitrate with aqueous sodium hydroxide, and extracting the free base with ether as before. 

The success of the Bart reaction when applied to nuclear- substituted anilines is often much affected by the pH of the reaction-mixture. Furthermore, the yields obtained from some m-substituted anilines, which under the normal conditions are usually low, arc considerably increased by the modifications introduced by Scheller, and by Doak, in which the diazotisation is carried out in ethanolic solution followed by reaction with arsenic trichloride in the presence of a cuprous chloride or bromide catalyst. 

B) Phenacyl and p-Bromophenacyl esters. The sodium salt of an acid in aqueous-ethanolic solution will react with phenacyl bromide, CjHjCOCHgBr, and with p-bromophenacyl bromide, BrC,H4COCH2Br... 

C) Phenacyl and p-Bromophenacyl esters. Ammonium salts in aqueous-ethanolic solution do not however usually condense satisfactorily with phenacyl and />-bromophenacyl bromide. The aqueous solution of the ammonium salt should therefore be boiled with a slight excess of sodium hydroxide to remove ammonia, and the solution then cooled, treated with hydrochloric acid until just alkaline to phenol-phthalein, and then evaporated to dryness. The sodium salt is then treated as described (p. 349) to give the ester. Filter the ester, and wash with water to remove senium halide before recrystallisation. 

Thiourea. Boil in ethanolic solution with benzyl chloride to prepare the crystalline benzylthiouronium chloride, m.p. lyo i 74" (P- 126). 

Anthraquinone and alizarin are unaffected by sulphurous acid. Phenanthraquinone is reduced in warm ethanolic solution by SO2 water to hydrophenanthraquinone, m.p. 147°. 1,2-Naphthoquinone gives the corresponding hydronaphthoquinone, m.p. 60°. Toluquinone gives toluhydroquinone, m.p. 124 . 

A) Picrates. Attempt precipitation of picrates by (a) mixing cold ethanolic solutions of the amine and of picric acid (saturated) or... 

A) Picrates. These are usually precipitated when ethanolic solutions... 

Some methiodides may separate inftially as sticky syrups in this case, redissolve a portion in ethanol and add to an ethanolic solution of prcric acid, when the yellow methopicrate is usually precipitated, and when filtered off and recrystallised, has often a sharp m.p. (M.ps., pp. 553-554.)... 

We chose benzyli dene acetone (4.39, Scheme 4.11) as a model dienophile for our studies. The uncatalysed Diels-Alder reaction of this compound with cyclopentadiene is slow, justifying a catalytic approach. Reaction of 4.39 with paraformaldehyde and dimethyl amine under acidic conditions in an aqueous ethanol solution, following a literature procedure, produced the HCl salt of 4.42 (Scheme 4.11). The dienophile was liberated in situ by adding one equivalent of base. 

The toluene solution from the previous step was treated with an ethanol solution of NaOEt (0.1 mol in 100 ml) at O C. When about a quarter of the solution had been added a thick precipitate formed and ether (100 ml) was added to maintain a fluid slurry. The remainder of the NaOEt was added and the slurry was stirred overnight. The solid was collected and w ashed with ether. It was then mixed with ether (200 ml) and 2NHC1 (75 ml) and shaken in a separatory funnel until the solid dissolved. The ether layer was washed with 2NHHC1 (2 X 50ml) and water and dried over MgS04. The solution was decolorized with Magnesol and evaporated to give the a-nitro ester as a red oil. 

The high reactivity of the 5-position in 1.3-selenazoles toward electrophilic substitution was also observed on azocoupling. By reacting molar quantities of an aqueous solution of a diazonium salt with an ethanolic solution of a 2-arylamino selenazole. for example, the corresponding 2-arylamino-5 azoselenazoles are formed in a smooth reaction (100). They deposit from the deeply colored solution and form intenselv red-colored compounds after their recrystallization from a suitable solvent (Scheme 36l. 

The ultraviolet absorption spectrum of thiazole was first determined in 1955 in ethanolic solution by Leandri et al. (172), then in 1957 by Sheinker et al. (173), and in 1967 by Coltbourne et al. (174). Albert in 1957 gave the spectrum in aqueous solution at pH 5 and in acidic solution (NHCl) (175). Nonhydroxylic solvents were employed (176, 177), and the vapor-phase spectrum was also determined (123). The results summarized in Table 1-15 are homogeneous except for the first data of Leandri (172). Both bands A and B have a red shift of about 3 nm when thiazole is dissolved in hydrocarbon solvents. This red shift of band A increases when the solvent is hydroxylic and, in the case of water, especially when the solution becomes acidic and the extinction coefficient increases simultaneously. 

As actually carried out the mixed aldol condensation product 1 3 diphenyl 2 propen 1 one has been isolated in 85% yield on treating benzaldehyde with ace tophenone in an aqueous ethanol solution of sodium hydroxide at 15-30°C... 

Poly(acrylic acid) and Poly(methacrylic acid). Poly(acryHc acid) (8) (PAA) may be prepared by polymerization of the monomer with conventional free-radical initiators using the monomer either undiluted (36) (with cross-linker for superadsorber appHcations) or in aqueous solution. Photochemical polymerization (sensitized by benzoin) of methyl acrylate in ethanol solution at —78° C provides a syndiotactic form (37) that can be hydrolyzed to syndiotactic PAA. From academic studies, alkaline hydrolysis of the methyl ester requires a lower time than acid hydrolysis of the polymeric ester, and can lead to oxidative degradation of the polymer (38). Po1y(meth acrylic acid) (PMAA) (9) is prepared only by the direct polymerization of the acid monomer it is not readily obtained by the hydrolysis of methyl methacrylate. 

Difluoroethanol [359-13-7], F2CHCH2OH, is a colorless Hquid with an alcohol-like odor mp, 28.2°C, bp, 96°C d[, 1.3084 n], 1.3320 heat of combustion, —1026 kJ/mol(—245.3 kcal/mol). It is stable to distillation and miscible with water and many organic solvents. As expected, its acidity Hes between that of 2-fluoroethanol and 2,2,2-trifluoroethanol both ia the gas phase (25) and ia 50% aqueous ethanol solution (26), where its of 1.0 x 10 is about 4.8 times smaller than that of trifluoroethanol. 

Pervaporation is a relatively new process with elements in common with reverse osmosis and gas separation. In pervaporation, a liquid mixture contacts one side of a membrane, and the permeate is removed as a vapor from the other. Currendy, the only industrial application of pervaporation is the dehydration of organic solvents, in particular, the dehydration of 90—95% ethanol solutions, a difficult separation problem because an ethanol—water azeotrope forms at 95% ethanol. However, pervaporation processes are also being developed for the removal of dissolved organics from water and the separation of organic solvent mixtures. These applications are likely to become commercial after the year 2000. 

Fig. 1. Solubility of vanillin in (a) ethanol solutions, (b) propylene glycol solutions, and (c) glycerol solutions, where A is 40°C B, 30°C C, 20°C D, 10°C ...

Confections. Main appHcations are sugared almonds, caramel, nougat, and sweets. For sugared almonds and caramel, vanillin is mixed into the sugar in the dry phase of the recipe. For nougat. Vanillin is added during the Hquid phase of manufacturing. In sweets, vanillin is added in the form of a 10% ethanol solution. 

Vanillin is used in flavored milk, desserts, yogurts, sorbets, and ice cream. Generally, vanillin is used in Hquid form either in ethanol solution with a vanillin concentration up to 400 g/L or in monopropylene glycol with a vanillin concentration to 300 g/L. Both concentrations are given for a temperature of 20°C to avoid recrystaUization problems. 

Dicarbocyanine and trie arbo cyanine laser dyes such as stmcture (1) (n = 2 and n = 3, X = oxygen) and stmcture (34) (n = 3) are photoexcited in ethanol solution to produce relatively long-Hved photoisomers (lO " -10 s), and the absorption spectra are shifted to longer wavelength by several tens of nanometers (41,42). In polar media like ethanol, the excited state relaxation times for trie arbo cyanine (34) (n = 3) are independent of the anion, but in less polar solvent (dichloroethane) significant dependence on the anion occurs (43). The carbocyanine from stmcture (34) (n = 1) exists as a tight ion pair with borate anions, represented RB(CgH5 )g, in benzene solution photoexcitation of this dye—anion pair yields a new, transient species, presumably due to intra-ion pair electron transfer from the borate to yield the neutral dye radical (ie, the reduced state of the dye) (44). 

In some instances, ring contraction is accompanied by cyclization to indole derivatives. For example, l-aryl-6-oxo-l,4,5,6-tetrahydropyridazines with a carboxyl or methyl group at position 3 give indoles when treated with an ethanolic solution saturated with hydrogen chloride or in the presence of BF3 etherate. 

The reaction was conveniently carried out in DME in the presence of benzophenone, and the yields were in the range 20-30%. In ethanol solution, 1,3,5-trimethylpyrazole (177 R = R = R = Me, R = H) yielded (183) and (184) (69T3287). In contrast with the previously observed sensitized photorearrangements (67HCA2244, 67CC488), this last reaction was not sensitized by acetophenone or benzophenone. 

When an ethanol solution of the oxime mixture of (360) and (361) was heated with a catalytic amount of hydrochloric acid, only one isoxazole (362) was formed. This regiospecific... 

Isothiazole has an absorption maximum in ethanol solution at 244 nm, with a molar absorptivity of 5200. This absorption occurs at a longer wavelength than with pyrazole or isoxazole, the displacement being due to the presence of the sulfur atom. A series of approximate additive wavelength shifts has been drawn up in Table 11 and this should enable prediction of UV maxima of isothiazoles with reasonable accuracy, even for multiply substituted compounds. The longest wavelength band results from a electronic... 

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