Acetic acid melting point

The mixture of 111.0 g of l,4-benzodioxan-2-yl-acetonitrile, 63.5 ml of sulfuric acid, 160 ml of acetic acid and 160 ml of water is refluxed for 48 h. It is poured on ice, the resulting solid collected to yield the l,4-benzodioxan-2-yl-acetic acid, melting point 100°C, (recrystallized from benzene-petroleum ether) [Belgium Pat. No. 613,211-July 30, 1962],... 

By treatment with a basic ion exchanger and crystallisation from ethanol/ether, there is obtained pure 1-amino-methyl-l-cyclohexane-acetic acid melting point 162-166°C. 

To a suspension of 3-(4-bromo-2-fluorobenzyl)-7-chloro-l,2,3,4-tetrahydro-2,4-dioxoquinazoline in N,N-dimethylformamide was added sodium hydride (60% in mineral oil) with stirring at 0°C and the mixture was stirred for 15 min at the same temperature. To this mixture was added ethyl bromoacetate and the mixture was stirred for 1 h at room temperature. The reaction mixture was poured into diluted hydrochloric acid and extracted with ethyl acetate. The extract was washed with brine, dried and evaporated to give a residue. Thus obtained product was purified by recrystallization from isopropyl ether to give 2-[3-(4-bromo-2-fluorobenzyl)-7-chloro-l,2,3,4-tetrahydro-2,4-dioxoquinazolin-l-yl]acetic acid melting point 223°-224°C. 

N-N-Dimethyl-2,4,6-trinitroaniline. Obtained from picryl chloride and dimethylamine (P. van Rombttrgh ). Recrystallized from glacial acetic acid. Melting point 141°. 

Catalytic Trimerization. About 0.01 mole of the aromatic nitrile togethter with 0.5 to 5.0 mole percent of the p-toluenesulfonic acid (PTSA) catalyst was introduced into a <+5-milliliter stainless steel pressure vessel. The vessel was flushed with nitrogen gas and the initial 2 pressure in the vessel was varied from 0 to 2.76 MH/m (0 to 1400 psi). The vessel was then heated to temperatures in the range of 100 to 316°C. The selected temperature was maintained for 2i4 to 90 hours. The PTSA catalyst and unreacted nitrile were then removed from the product by washing with water followed by distillation under reduced pressure. The product was then recrystallized from xylene or glacial acetic acid. Melting point and infrared spectrum were determined for identification purposes. 

Solubility Insoluble in water soluble in ethanol, ether, benzene, acetic acid Melting Point 130-132°C... 

Solubility Insoluble in water, benzene, chloroform, ether Soluble in acetone, N,N-dimethylformamide, dimethyl sulfoxide, hot ethanol, glacial acetic acid Melting Point >350 C 314-316 °C 2h24... 

Solubility Soluble in water, lV,N-dimethylformamide, dimethyl sulfoxide slightly soluble in glacial acetic acid Melting Point >300 °C pKa 7.3, temperature 22 °C... 

The organic layer wasdried with anhydrous magnesium sulfate and then filtered. The solution was concentrated under vacuum at 30°C to 35°C until reduced to half of its original volume and then cooled to 5°C to allow the crystallization of the compound. Thus, the cake was filtered, washed with cool ethyl acetate, and dried under vacuum. Yield 74% (76.7 g) of phthalidyl ester of 2-(3 -trifluoromethylanilino)-pyridin-3-carboxylic acid, melting point 165°C to 167°C. 

A mixture of 2 ml of morpholine, 3 ml of dimethylformamide and 10 ml of water was heated to 60°C and under stirring the equal molecular quantity of 6-isopropyl-4-oxo-4H-l-benzopyran-3-carbonitrile was added for 5 minutes. The mixture was heated at that temperature for one hour and the resultant precipitate was filtered, rained with water recrystallized from acetic acid and washed with chloroform. By the above procedure was obtained 2-amino-6-isopropyl-4-oxo-4H-l-benzopyran-3-carboxaldehyde melting at 206°-208°C. A mixture of 4 ml ethyl cyanoacetate, 50 ml of ethanol, 5 ml of piperidine and the equal molecular quantity of 2-amino-6-isopropyl-4-oxo-4H-l-benzopyran-3-carboxaldehyde was refluxed for 30 minutes and, after cooling, the crystalline precipitate was filtered and washed with chloroform. By above procedure was obtained ethyl-2-amino-7-isopropyl-l-azaxanthone-3-carboxylate, melting after recrystallization from ethanol at 243°-244°C. A mixture of 10 ml of acetic acid and 10 ml of 55% sulfuric acid the equal molecular quantity and 2-ethyl-amino-7-isopropyl-l-azaxanthone-3-carboxylate was stirred at 130°C for 4 hours and, after water was added, the precipitate was collected by filtration and recrystalllized from dimethylformamide to give the 2-amino-7-(l-methylethyl)-5-oxo-5H-[l]benzopyrano[2,3-b]pyridine-3-carboxylic acid, melting point 300°C. 

After cooling of the medium, 120 ml of water containing 11.6 g of sodium carbonate and ether are introduced, the aqueous phase is decanted and washed with ether, whereupon the aqueous phase is acidified to a pH of 1 with 50% hydrochloric acid. The desired product is extracted with ethyl acetate. After elimination of the extraction solvent 31.5 g of the 4-(3,4,5-trimethoxyphenyl)-4-oxo-2-hydroxy butanoic acid, melting point 119°-120°... 

Ethyl 7-(4-ethoxycarbonyl-l-piperazinyl)-6-fluoro-l,4-dihydro-4-oxo-l,8-naphthyridine-3-carboxylate was suspended in dimethylformamide (10 ml) and to the suspension was added potassium carbonate (0.53 g). After the mixture was kept at 60°C for 10 minutes with stirring, ethyl iodide (1.2 g) was added to the solution. The mixture was stirred for 2 hours at 60°-70°C. The reaction mixture was concentrated to dryness under reduced pressure, and water was added to the residue. After extraction with chloroform, the chloroform extract was dried over anhydrous potassium carbonate. After removal of the chloroform by distillation, the resulting precipitate was recrystallized from a mixture of dichloromethane and n-hexane to give 0.89 g of ethyl l-ethyl-6-fluoro-l,4-dihydro-4-oxo-7-(4-ethoxycarbonyl-l-piperazinyl)-l,8-naphthyridine-3-carboxylate (mp 171°-173°C). A mixture of the above ethyl ester (0.8 g), 10% sodium hydroxide (6 ml) and ethanol (2 ml) was refluxed by heating for 3 hours. After cooling, the solution was adjusted to pH 7.0-7.5 with 10% acetic acid. The precipitate was collected by filtration, washed with ethanol and recrystallized from a mixture of dimethylformamide and ethanol to give 0.57 g of l-ethyl-6-fluoro-l,4-dihydro-4-oxo-7-(l-piperazinyl)-l,8-naphthyridine-3-carboxylic acid. Melting point 220°-224°C. 

The aqueous phase was extracted with ethyl acetate, the organic layers collected, dried (MgS04) and the solvent removed in vacuo to yield 8.71 g of a 4 -methylbiphenyl-2-carboxylic acid, melting point 140.0-145.0°C. 

Hydroxy-6-methoxybenzaldehyde (16.875 g, 0.111 M), ethyl 5-bromopentanoate (23.25 g, 17.6 ml, 0.111 M), anhydrous potassium carbonate (16.5 g), sodium iodide (0.675 g) and 95% ethanol (150 ml) were refluxed with stirring (16 hours). The cooled reaction mixture was filtered and the solid washed well with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether and water. The ethereal layer was separated and washed with 2 N sodium hydroxide solution, water, dried (sodium sulfate) and evaporated. The residue was dissolved in 95% ethanol (300 ml) and 0.66 N sodium hydroxide solution (450 ml) and stirred at ambient temperature (4 hours). The reaction mixture was evaporated to half volume and diluted with water. The mixture was extracted once with ether and the aqueous layer acidified with concentrated hydrochloric acid with cooling. The crystalline solid formed was filtered off and washed well with water. Recrystallisation from ethyl acetate-petrol gave 5-(2-formyl-3-methoxyphenoxy)pentanoic acid, melting point 99-101°C. 

A mixture of 40.6 g of the ethyl 1,3-dihydro-2-oxo-3-benzyl-lH-benzimidazol-1-butanoate and 400 ml of 1 N methanolic sodium hydroxide was refluxed for 3 h under an inert atmosphere and was then concentrated to 0.5 its value and was poured into 1 L of iced water. The pH was adjusted to 2 by addition of concentrated hydrochloric acid and the mixture was vacuum filtered. The product was washed and dried to obtain 35.2 g of 1,3-dihydro-2-oxo-3-benzyl-lH-benzimidazol-l-butanoic acid, melting point 168°C (crystallization from ethyl acetate). 

Properties of Acetic Acid (Section 112).—(a) Solubility of acetic acid.—Test the solubility of acetic acid in water, alcohol, ether, and benzene. Place about 10 cc. of the acid obtained in a test-tube surrounded by chipped ice and water. Insert a thermometer into the acid. If crystals do not form, scrape the side of the tube with a glass rod. If the acid freezes, remove the tube, stir with the thermometer, and note the temperature when the acid is about one-fourth melted.2 Pure acetic acid melts at 16.7° and boils at 119°. One per cent of water lowers the melting-point about 2.1°. 

Cresol purple always has a dark color which indicates the presence of the quinoid structure. W. R. Orndorff and A. C. Purdy find that the crystalline material contains about 1% of water. The crystals appear to reflect a dark green light, and yield a dark red powder when pulverized. It is slightly soluble in water (yellow), dissolves readily in methyl alcohol, ethyl alcohol, and glacial acetic acid, but is insoluble in benzene, ether, carbon tetrachloride, petroleum ether, and ethyl acetate. Its melting point is not clearly defined. 

Crystalline acetic acid melts below its given melting point when kept in air. Why ... 

It is a well-known fact that substances like water and acetic acid can be cooled below the freezing point in this condition they are said to be supercooled (compare supersaturated solution). Such supercooled substances have vapour pressures which change in a normal manner with temperature the vapour pressure curve is represented by the dotted line ML —a continuation of ML. The curve ML lies above the vapour pressure curve of the solid and it is apparent that the vapour pressure of the supersaturated liquid is greater than that of the solid. The supercooled liquid is in a condition of metastabUity. As soon as crystallisation sets in, the temperature rises to the true freezing or melting point. It will be observed that no dotted continuation of the vapour pressure curve of the solid is shown this would mean a suspended transformation in the change from the solid to the liquid state. Such a change has not been observed nor is it theoretically possible. 

The sulphides (I) can be readily oxidised in glacial acetic acid solution by potassium permanganate to the corresponding sulphones (II) the latter exhibit a wide range of melting points and are therefore particularly valuable for the characterisation of mercaptans ... 

Crystallise the two lots of crude active aec. -octyl hydrogen phthalates separately twice from 90 per cent, acetic acid use 2 g. of acetic acid to each gram of soUd. The recrystaUised esters, if optically pure (8), will melt sharply at 75° if the melting points are below 75°, further recrystallisation is necessary. The yields of optically pure products, m.p. 75°, are 48 g. and 49 g. respectively. 

Compounds that readily undergo thermal decarboxylation include those related to malonic acid On being heated above its melting point malonic acid is converted to acetic acid and carbon dioxide... 

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

---