Formic acid, anhydrous preparation

Lead formate separates from aqueous solution without water of crystallisation. It can therefore be used for the preparation of anhydrous formic acid. For this purpose, the powdered lead formate is placed in the inner tube of an ordinary jacketed cond ser, and there held loosely in position by plugs of glass-wool. The condenser is then clamped in an oblique position and the lower end fitted into a receiver closed with a calcium chloride tube. A current of dry hydrogen sulphide is passed down the inner tube of the condenser, whilst steam is passed through the jacket. The formic acid which is liberated... 

Intermediate formation of formyl chloride is not necessary since the actual alkylating agent, HCO", can be produced by protonation of carbon monoxide or its complexes. However, it is difficult to obtain an equimolar mixture of anhydrous hydrogen chloride and carbon monoxide. Suitable laboratory preparations involve the reaction of chlorosulfonic acid with formic acid or the reaction of ben2oyl chloride with formic acid ... 

Bromo-4-methoxy-A-homo-estra-2,4,5(10)-trien-17-one (44 0. 2g), is dissolved in formic acid, 2 ml of boron trifluoride etherate is added and the mixture is stirred vigorously at 0° for 2 hr. A brown mass ca. 0.12 g) is obtained after evaporation of the solvents at reduced pressure. This material is diluted with water and extracted with chloroform. The chloroform extracts are washed successively with water and saturated salt solution, dried over anhydrous magnesium sulfate and evaporated at reduced pressure to give 95 mg of a product which is purified by filtration through a column of neutral alumina and crystallization of the residue after evaporation of the solvent from ethyl acetate-petroleum ether. The resulting A-homo-estra-l(10),2,4a-triene-4,17-dione (45), mp 143-146°, is identical to the tropone (45) prepared from monoadduct 17-ketone (43a). 

Other preparations and isolations. If damp methylenedi(nitroformamide) is allowed to stand for several days, the odor of formic acid is noticed, and MEDINA can be isolated from the residue (Ref 11, p 14). The details of scale-up to 150 lb batches, including exp details and flow sheets, and further scale-up with the aim of prodn of 1000 lbs are given. The report describes a fume-off and fire which occurred during the S3rd run. The cause was attributed to a stuck valve which allowed nitric acid to build up in the reactor (Ref 13, p 57). In Ref 16, p 73 there are cost analysis data for pilot plant and large scale prodn, flow sheet for a proposed coml plant, and material balances. The action of acet anhydr on N,Nf-bis(hydroxy-methyl)MEDlNA regenerates MEDINA (Ref 6) the diNa salt of N. N trinitrotrimethylene-diamine, on warming with me ale, ppts the Na salt of MEDINA... 

To prepare the sodium formate solution, a filtered solution of 15 g. (0.14 mole) of anhydrous sodium carbonate in 80 ml. of water is diluted to 120 ml. Approximately 4 ml. (4.9 g., 0.10 mole) of 99% formic acid (a commercial grade) is then added dropwise until the solution is weakly alkaline to phenolphthalein. 

Preparation of 17-cyclopropylmethyl-14-hydroxynorcodeinone. A solution of 17-cyclopropylmethylnorcodeinone (0.20 g, 0.59 mmol), formic acid (90%, 0.304 g), water (0.504 g), EtOAc (0.27 g), and hydrogen peroxide (30%, 0.17 g) was heated at 42°-43°C for 15 hr, added water (20 ml), basified with Na2C03 (1.02g), and extracted with EtOAc (80 ml and 2 times 20 ml). The combined extract was washed with water, dried over anhydrous sodium sulfate, and evaporated in vacuo to dryness to give 17-cyclopropylmethyl-14-hydroxynorcodeinone (0.10 g, 56% yield). The Rf value in TLC and the IR spectrum of the product were comparable to those obtained from an authentic sample. 

Cognate preparations. Ethyl formate. Reflux a mixture of 61 g (50 ml, 1.33 mol) of formic acid (98/100%) and 31 g (39.5 ml, 0.67 mol) of absolute ethanol for 24 hours. Attach a fractionating column to the flask, distil and collect the liquid passing over below 62 °C. Wash the distillate with saturated sodium hydrogen carbonate solution and saturate with salt before removing the ester layer. Dry with anhydrous sodium sulphate, filter and distil. The ethyl formate passes over at 53-54 °C. The yield is 36 g (72%). 

Pentathiazyl tetrachloroaluminate(l —) and, to a lesser extent, penta-thiazyl tetrachloroferrate(l —) are moisture-sensitive both are soluble in thionyl chloride, anhydrous formic acid, and concentrated sulfuric and nitric acids. On dissolution in acid, hydrogen chloride is evolved because of decomposition of the anion. The solution in anhydrous formic acid can be used to prepare other salts by metathesis.7 The hexachloroantimonate(l —) undergoes almost no reaction when exposed to water or moist air for 24 hr. 

Aromatic aldehydes are prepared by passing carbon monoxide and dry hydrogen chloride through an ether or nitrobenzene solution of an aromatic hydrocarbon in the presence of a catalyst, commonly aluminum chloride with cuprous chloride as a carrier. The process is illustrated by the synthesis of p-tolualdehyde (51%). A convenient procedure for obtaining an equimolar mixture of anhydrous hydrogen chloride and carbon monoxide consists in dropping chlorosulfonic acid on formic acid, viz.,... 

Carbon monoxide is very toxic by inhalation TLV 50ppm. Prepare by slow addition of anhydrous formic acid to concentrated sulphuric acid at 90-100°C (frothing tends to be a problem). One millilitre of formic acid generates 26.6 mmoles of gas. The CO is contaminated with small amounts of carbon dioxide and sulphur dioxide which may be removed by passage over potassium hydroxide or the commercial product Ascarite (sodium hydroxide on silica). Dispose of carbon monoxide by slow venting in an efficient hood. 

Iminium salt 47 is reduced with anhydrous SnCl2 to RCH=NH, which precipitates as a complex with SnCl4 and is then hydrolyzed (16-2) to the aldehyde. The Stephen reduction is most successful when R is aromatic, but it can be done for aliphatic R up to about six carbons.It is also possible to prepare 47 in a different way, by treating ArCONHPh with PCI5, which can then be converted to the aldehyde. This is known as the Sonn-Muller method. Aqueous formic acid in the presence of Pt02, followed by treatment with aqueous acid, converts aryl nitriles to aryl aldehydes. ... 

Acidolysis. One method for the preparation of anhydrous acrylic acid is by heating methyl acrylate with 98% formic acid in the presence of a catalytic amount of sulfuric acid and of hydroquinone as polymerization inhibitor. ... 

Sample preparation Microsomal incubations. Extract 10 mL microsomal incubations with 30 mL ethyl acetate acetone 2 1, centrifuge. Remove organic layer and dry it over anhydrous sodium sulfate, filter, evaporate under vacuum, reconstitute in n-propanol, inject an aliquot. Bile. Acidify to pH 3.5 with 20 mM formic acid, extract with toluene n-propanol 85 15, extract with n-butanol saturated with water, combine extracts, evaporate under vacuum, reconstitute in n-propanol, inject an aliquot. 

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