Acetamide in water

In short, our S-MC/QM methodology uses structures generated by MC simulation to perform QM supermolecular calculations of the solute and all the solvent molecules up to a certain solvation shell. As the wave-function is properly anti-symmetrized over the entire system, CIS calculations include the dispersive interaction[35]. The solvation shells are obtained from the MC simulation using the radial distribution function. This has been used to treat solvatochromic shifts of several systems, such as benzene in CCI4, cyclohexane, water and liquid benzene[29, 37] formaldehyde in water(28, 38] pyrimidine in water and in CCl4(31] acetone in water[39] methyl-acetamide in water[40] etc. 

The solubility of noble gases in various solutions (often aqueous-nonaqueous mixtures) gives indications of both hydrophobic and hydrophilic effects (Fig. 2.68). When substances exhibiting both effects are present, there is a maximum in the solubility of argon. Thus (Fig. 2.68, curve 1) in the system water-acetone, no hydrophilic effects are caused by the added solvent component, and the solubility increases. On the other hand, for systems in which urea is added, there are no hydrophobic effects and the solubility or the gas therefore deaeases. In curve 2 of Fig. 2.68, hydrophilic and hydrophobic effects compete (due to the properties of acetamide in water) and there is a maximum on the curve. 

D) Acid and Basic Properties of Amides. (1) Determine the pH of a sample of pure acetamide in water. Which amide is most likely to show definite acidic properties Devise a test to show that acetamide forms salts with metallic ions. 

Jorgensen and coworkers used the Monte Carlo simulation program BOSS 3.1 to calculate A log P for the urea and acetamide in water and chloroform. The computed A log P was 1.98 0.11 which is close to the experimental result of 1.90. Richards and coworkers used AMBER 3.1 to calculate... 

The solubility of antibiotic chloramphenicol (2,2-dichloro-N-[l,3-dihydroxy-l-(4-nitrophenyl) propan-2-yl]acetamide) in water is relatively low ( 2.5 g/L at 25 C). Therefore, to prepare chloramphenicol/silica composites, the impregnation method was used (Krupska et al. 2006). The LT H NMR spectroscopy study of these composites showed that the free surface energy Ys of interfacial water decreases with increasing amount of chloramphenicol in the composition (Figure 1.165, curve 1). This can be interpreted as displacanent of water from the silica surface by the drug molecules. However, despite the maximal amount of chloramphenicol (1 mmol/g) greater than the content of surface silanols (Cqh 0.6-0.7 mmol/g for A-300 samples), the perturbation... 

Similar works were performed for the description of the photo-physics of formamide in an Ar matrix [855], the nonadiabatic deactivation of azomethane in gas phase, water and -hexane [856], the cis-trans isomerization of iV-methyl-acetamide in water [516] and the ultrafast nonadiabatic dynamics of Nat in a water cluster [857]. By comparing to an older work of Koch et al. [857] the latter study allows an insight into the importance of polarizable force fields for the description of charge-transfer (CT) states. Solvent effects on the vertical spectra of small carbonyl compounds were computed by Malaspina et al. [858], Nielsen et al. [859] and Lin and Gao [860]. Using CASSCF approaches in combination with the solvent model based on the polarizable NEMO force field [861], Hermida-Ramon et al. studied the influence of water as a solvent on the balance between zwitterionic and biradical valence structures of methylene peroxide [862]. 

Dissolve 36 g. of sodium hydroxide in 160 ml. of water contained in a 500 ml. conical flask, and chill the stirred solution to 0-5° in ice-water. Now add io-8 ml. (32-4 g.) of bromine slowly to the stirred solution exercise care in manipulating liquid bromine ) during this addition the temperature rises slightly, and it should again be reduced to 0-5°. Add a solution of 12 g. of acetamide in 20 ml. of water, in small portions, to the stirred hypobromite solution so that the temperature of the mixture does not exceed 20° the sodium acet-bromoamide is thus obtained in the alkaline solution. Now remove the flask from the ice-water, and set it aside at room temperature for 30 minutes. 

By the action of concentrate aqueous ammonia solution upon esters. This process is spoken of as ammonolysls of the ester, by analogy with hydrolysis applied to a similar reaction with water. If the amide is soluble in water, e.g., acetamide, it may be isolated by distillation, for example ... 

The acetamide often contains a minute amount of impurity having an odour resembling mice excrement this can be removed by washing with a small volume of a 10 per cent, solution of ethyl alcohol in ether or by recrystallLsation. Dissolve 5 g. of impure acetamide in a mixture of 5 ml. of benzene and 1 5 ml. of dry ethyl acetate warm on a water bath until all is dissolved and cool rapidly in ice or cold water. Filter oflF the crystals, press between Alter paper and dry in a desiccator. The unpleasant odour is absent and the pure acetamide melts at 81°. Beautiful large crystals may be obtained by dissolving the acetamide (5 g.) in warm methyl alcohol (4 ml.), adding ether (40 ml.) and allowing to stand. 

Place 25 g. of dry acetamide in a 350 ml. conical or flat-bottomed flask, and add 69 g. (23 ml.) of bromine (CAUTION ) a deep red liquid is produced. Cool the flask in ice water and add 10 per cent, sodium hydroxide solution (about 210 ml.) in small portions and with vigorous shaking until the solution acquires a pale yellow colour. At this stage the bromoacetamlde is present in the alkaline solution. If any solid should crystallise out, add a little water. 

Nitrosomethylurea. Acetamide method. To a solution of 59 g. of acetamide in 88 g. (28 ml.) of bromine (1) in a 4-litre beaker add dropwise, with hand stining, a solution of 40 g. of sodium hydroxide in 160 ml. of water. Heat the resulting yellow reaction mixture on a steam bath until eflfervescence sets in (2), after which continue the heating for 2-3 minutes. CrystaUisation of the product from the yellow or red coloured solution usually commences immediately. Cool in an ice bath for 1-2 hours, collect the product by suction filtration, wash with a little ice-cold water, and dry in the air. The yield of colourless acetylmethylurea, m.p. 178-180°, is 50 g. 

Solubility. Poly(vinyl alcohol) is only soluble in highly polar solvents, such as water, dimethyl sulfoxide, acetamide, glycols, and dimethylformamide. The solubiUty in water is a function of degree of polymerization (DP) and hydrolysis (Fig. 4). Fully hydrolyzed poly(vinyl alcohol) is only completely soluble in hot to boiling water. However, once in solution, it remains soluble even at room temperature. Partially hydrolyzed grades are soluble at room temperature, although grades with a hydrolysis of 70—80% are only soluble at water temperatures of 10—40°C. Above 40°C, the solution first becomes cloudy (cloud point), followed by precipitation of poly(vinyl alcohol). 

Amides are stable compounds. The lower-melting members (such as acetamide) can be readily purified by fractional distillation. Most amides are solids which have low solubilities in water. They can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent. Amides can be freed from solvent or water by drying below their melting points. These purifications can also be used for sulfonamides and acid hydrazides. 

A. N-(Hydroxymethyl)acetamide. A solution of 10 g. (0.07 mole) of anhydrous potassium carbonate in 137 g. of a 36-38% solution of formaldehyde (1.7 moles) in water (Note 1) is prepared in a 2-1., round-bottomed flask, and lOOg. (1.7 moles) of... 

A plefhora of methods developed for the determination of triazine compounds in water, soil, crops, biological fluids, etc., have been reported in the literature, and several excellent reviews are available for the interested reader. " More method papers are published on the determination of triazines in water than for all other sample matrices combined (water > soil > crop). The majority of the water method reports relate to the determination of parent triazine compounds plus compounds from one or more other chemical classes of pesticides (e.g., phenoxy acids, carbamates, pheny-lureas, acetanilides, acetamides, organophosphorus compounds, etc.) for generalized multi-residue screening or monitoring purposes. Addressed in other more selective... 

Thus amides are found to be only very weakly basic in water [pKa for ethanamide(acetamide) is =0-5], and if two C=0 groups are present the resultant imides, far from being basic, are often sufficiently acidic to form alkali metal salts, e.g. benzene-1,2-dicarboximide (phthalimide, 8) ... 

Alternatively, dissolve 220 g 4-benzyloxy-3-indoleacetic acid (or equimolar amount other indoleacetic acid) in 2 L absolute methanol and reflux six hours in the presence of 20 g Dowex 50X8 sulfonic acid resin. Filter (decolor with carbon if desired) and concentrate below 35° until precipitation starts then cool to precipitate and filter to get 200 g of the methyl ester. Add 200 g of the ester to 600 ml 40% aqueous methylamine over twelve hours with vigorous stirring. Filter, wash precipitate with water and dry to get 187 g of the N-methyl-acetamide (reflux two hours in 500 ml benzene to remove unreacted ester). 24 g of the acetamide in 300 ml tetrahydrofuran is added dropwise to 10 g lithium aluminum hydride in 300 ml tetrahydrofuran reflux ten hours, cool to 15° and add dropwise with stirring 50 ml ethyl acetate. Reflux two hours and proceed as above to get 15 g (II) or analog. 

Two of the worst outliers were N,N-dimethylformamide and N,N-dimethyl-acetamide. For both of these, solubility in water was greatly underestimated. This may illustrate a situation in which conformation does assume importance. In the gas phase structures used to compute the surface properties, the nitrogens are planar. There is reason to believe, however, that interaction with water molecules will cause the nitrogens to become pyramidal,48 since that produces more localized lone pairs that better attract water hydrogens. Thus, analysis involving planar nitrogens would not indicate the true strength of the interaction. 

Experiment.—A small quantity of acetamide is dissolved in water, mixed with a little yellow oxide of mercury, and warmed. The oxide goes into solution and the compound formulated above is formed. 

Photolytic. Mathew and Khan (1996) studied the photolysis of metolachlor in water in the presence of kaolinite, montmorillonite, and goethite and fulvic acid under neutral and acidic conditions at 22 °C. Metolachlor degraded in all the treatments at both pH conditions. The rate of photolysis and degradation products formed was dependent on the duration of UV exposure, the initial pH of the solution, and the composition of the suspended/dissolved material. The following photoproducts identified included 2-hydroxy-A-(2-ethyl-6-methylphenyl)-A-(2-methoxy-l-meth-ylethyl)acetamide, 4-(2-ethyl-6-methylphenyl)-5-methyl-3-morpholine (major product forming at 74-84% yield), 8-ethyl-3-hydroxy-A-(2-methoxy-l-methylethyl)-2-oxo-l,2,3,4-tetrahydroquino-line, 2-chloro-A -(2-(l-hydroxyethyl)-6-methylphenyl)-7V-(2-hydroxy-l-methylethyl)acetamide, and 2-chloro-A -(2-ethyl-6-hydroxymethylphenyl)-A-(2-methoxy-l-methylethyl)acetamide. 

Hydration of nitriles providing carboxamides is usually carried out m strongly basic or acidic aqueous media - these reactions require rather bars conditions and suffer from incomplete selectivity to the desired amide product. A few papers in the literature deal with the possibihty of transition metal catalysis of this reaction [28-30]. According to a recent report [30], acetonitrile can be hydrated into acetamide with water-soluble rhodium(I) complexes (such as the one obtained from [ RhCl(COD) 2] and TPPTS) under reasonably mild conditions with unprecedently high rate... 

The synthesis of a water-soluble diphenylmethano-bridged fullerene 122 was achieved by hydrolyzing the bis (acetamide) 121 with acetic acid-aqueous hydrochloric acid and then converting it into the bis(succinamide) 122 by treatment with succinic anhydride (Scheme 4.25) [158]. Compound 122 is soluble in water at pH > 7. This is an important requirement for the investigation of the biological activity of fullerenes. Remarkably, 122 is an inhibitor for the HIV enzymes protease (HIV-P) and reverse transcriptase (HIV-RT) [159]. As suggested by molecular modeling. 

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