N- acetic acid

Riboflavin forms fine yellow to orange-yeUow needles with a bitter taste from 2 N acetic acid, alcohol, water, or pyridine. It melts with decomposition at 278—279°C (darkens at ca 240°C). The solubihty of riboflavin in water is 10—13 mg/100 mL at 25—27.5°C, and in absolute ethanol 4.5 mg/100 mL at 27.5°C it is slightly soluble in amyl alcohol, cyclohexanol, benzyl alcohol, amyl acetate, and phenol, but insoluble in ether, chloroform, acetone, and benzene. It is very soluble in dilute alkah, but these solutions are unstable. Various polymorphic crystalline forms of riboflavin exhibit variations in physical properties. In aqueous nicotinamide solution at pH 5, solubihty increases from 0.1 to 2.5% as the nicotinamide concentration increases from 5 to 50% (9). 

The mixture is refluxed with stirring for ten hours, cooled and filtered. The filtrate is extracted three timas with 200 cc portions of 6 N acetic acid. The aqueous acetic acid solution is then made strongly basic with 10% sodium hydroxide solution, and extracted three times with 200 cc portions of ether. The ether extract is dried with anhydrous sodium sulfate, stirred with 5 g of activated carbon and filtered to provide 2-[p-chloro-a(2-di-methylaminoethoxylbenzyll pyridine in solution. Addition of a solution of 116 g (1 mol) of maleic acid in 1,500 cc of ether gives 323 g (79%) of solid which, on recrystallization from ethyl acetate, gives white solid 2-[p-chloro-a(2-dimethvlaminoethoxv)benzyl] pyridine maleate melting at 117° to 119°C. 

A mixture of 4.9 grams of 5,6-dihydro-6-oxo-morphanthridine, 37 ml of phosphorus oxychloride and 1.5 ml of dimethylaniline Is heated for 3 hours at reflux. The viscous oil, obtained by evaporation of the reaction mixture in vacuo at 60°C, Is diluted with 20 ml of absolute dioxane and, after adding 30 ml of N-methylpiperazine, heated for 4 hours at reflux. The resulting clear solution Is evaporated in vacuo at 60°C to dryness. The residue is distributed between ether and ammonia water. The ethereal solution is separated, washed with water and then extracted with 1 N acetic acid. The acetic acid extract is mixed with ammonia water and then extracted with ether. The ethereal solution is washed with water, dried over sodium sulfate, filtered through alumina and evaporated. 

Benzyl cyanide is first reacted with 2-butylbromide in the presence of sodium amide to give 2-phenyl-3-methylvaleronitrile which is hydrolyzed by sulfuric acid to give 3-methyl-2-phenyl-pentanoic acid. 24 g of 2-phenyl-3-methyl-pentanoic acid are heated for one hour at 175° to 185°C with 30 g of 2-diethylaminoethanol and 0.5 g of sodium methylate. The excess diethyl-aminoethanol is removed in vacuo, the residue is dissolved in 300 cc of 2 N-acetic acid, the acid solution is shaken with ether and made alkaline with concentrated potassium carbonate solution and ice. The ether solution Is washed with water, dried with sodium sulfate and evaporated. The residue is distilled under high vacuum, yielding 20 to 21 g of the basic ester (60% of the theoretical) is obtained, the ester boiling at 98° to 100°C at a pressure of 0.03 mm. The hydrochloride of the ester melts at 112° to 113°C and the methobromide at 100° to 101°C. 

Hydantoin, the cyclic form of hydantoic acid, was detected in the Murchison meteorite and also as a product of polymerisation of HCN (Ferris et al 1974). The yields obtained (based on cyanoacetaldehyde) were 18% for cytosine-N -acetic acid, but only 1.8% for the corresponding uracil derivative (1 mM cyanoacetaldehyde and 2 M hydantoic acid were allowed to react at around 373 K). 

A similar ion-exchange resin method was used by Ling in 1955 (LI) for the examination of combined amino acids in urine. According to this procedure urine was desalted and simultaneously freed from amino acids by using Amberlite IR-112, H+-form resin. The effluent collected from the column was then fractionated on Amberlite IRA, OH--form resin, by successive elution with 0.16 N acetic acid, 0.08 N formic acid, 0.25 N formic acid, 0.08 N hydrochloric acid, and finally with 0.16 N formic acid. The solutions of all acids contained 10% of acetone. The collected fractions were hydrolyzed with hydrochloric acid and the liberated amino acids identified by means of paper chromatography. 

Experiments.—In order to learn, at least qualitatively, the influence of the hydrogen ion concentration on the velocity of decomposition, about 0-5 c.c. of ethyl diazoacetate is dissolved in a little 50 per cent alcohol and the solution is divided into two portions in small beakers to which respectively 1 c.c. of 0-1 AT-hydrochloric acid and 1 c.c. of 0-1 N-acetic acid (prepared in a measuring cylinder from glacial acetic acid) are added. 

Methyldihydrocodeinone. A solution of bromomethyldihydrocodeinone (18.2 g) in 200 cc of 2 N acetic acid with 5 g of potassium acetate, a small amount of gum aribic, and 10 cc of 1% palladius chloride solution, was hydrogenated (see reductions chapter for instructions to hydrogenate). Remove the catalyst by filtration, make alkaline with NaOH, and extract with small portions of ether until a total of 2 liters is used. Combine the ether extracts, wash thoroughly with dilute alkali, and filter off the 12 g of white crystalline product. Recrystallize with ether or ethyl acetate to get mp of 144-144.5°. 

Dilute collagen stock solution to 50 pg/mL in 0.02 N acetic acid. 

Mix, adjust pH 7.0 with 4 N NaOH and 4 N acetic acid, respectively ... 

Polymer Monomer Product fraction Type % Content of respectively N, acetic acid, orCl,% Graft polymer %... 

Soluble glutenins Insoluble glutenins 15-35 Extractable in dilute acid or alkali (e.g., 0.05 N acetic acid) High-MW (100,000-3,000,000) complexes containing low-MW (40,000-10,000) subunits linked by disulfide bonds extra stabilization by hydrogen and hydrophobic interactions Rich in Glu, Pro, and hydrophobic amino acids, and low content of basic amino acids Glu and Asp in primarily amide form low net charge... 

Persulfates Benzidine (0.05% in 1 N acetic acid) Blue spots 77... 

After the compounds of interest are eluted from the column, the concentration is linearly increased to 0.1 N acetic acid in 95% (v/v) ethanol/water to remove the more nonpolar components retained on the column. Following an adequate equilibration (greater than 10 column volumes) at maximum solvent strength (95% ethanol), the solvent is linearly programmed to return to the initial conditions of 0.1 N aqueous acetic acid. 

Collidine acetate 7.0 9.1 ml Collidine 46 ml N acetic acid 500 volts 3 (Nl)... 

Calculate the pH value of 0.01 N acetic acid. What color would this solution impart to methyl orange ... 

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