Fluoboric add

Bor-fluorid, n. boron fluoride borofluoride. fiuorwasserstoffsaure, /., -fiuorwasserstoff, m. fluoboric acid, hydrofluoboric acid, HBFi. -flusssSure,/. fluoboric add. 

To a solution of 0.200 g. (0.515 mmole) of dry dihydrocholesterol (Note 1) in 10 ml. of methylene chloride contained in a 50-ml. Erlenmeyer flask is added 0.3 ml. of a catalyst stock solution containing 0.0016 ml. (0.018 mmole) of concentrated fluoboric add (Note 2) in 3 1 anhydrous diethyl ether-methylene chloride (Note 3). The solution is swirled, and a 0.451/ solution of diazo-methaue (Note 4) in dry methylene chloride is added from a buret (Note 5) at a rate of about 2 ml. per minute. The yellow color of diazomethane disappears rapidly on contact with the reaction mixture and nitrogen is vigorously evolved. When about 3 ml. of diazomethane solution has been added, the reaction becomes sluggish. The yellow color persists for several minutes after the total amount of 3.9 ml. of diazomethane solution (1.76 mmoles) has been added (Note 6). After 1 hour the reaction mixture is filtered to remove a small amount of amorphous polymethylene, which is washed with methylene chloride. The washings are combined with the methylene chloride solution, washed with 5 ml. of saturated aqueous sodium bicarbonate, with three... 

Fluoboric add is now a commercial product. For this size preparation, 355.5 g. of the commercial 40 per cent fluoboric acid is required. 

A corresponding amount of 48 per cent or of 52 per cent hydrofluoric acid may also be used. The quantities given represent an excess of fluoboric add. A larger excess may be taken but does not appreciably influence the yield. Fluoboric add (40 per cent) is now a commerdal product. 

Stannous and lead fluoborates are the source of metal.Their concentrations and ratio must be strictly maintained, as they will directly affect alloy composition. Fluoboric acid increases the conductivity and throwing power of the solutions. Boric acid prevents the formation of lead fluoride. Additives promote smooth, fine-grained, tree-free deposits. Excess peptone (three to four times too much) may cause pinholes (volcanoes) in deposit when reflowed. Testing by Hull cell and periodic carbon treatments is indicated.The peptone add rate is about 1 to 2 qt per week for a 400 gal tank. Only DI water and contamination-free chemicals should be used—for example, <10 ppm iron-free and <100 ppm sulfate-free fluoboric add. A clear solution is maintained by constant filtration. 

The name silicon was proposed by Thomson, since the element is non-metallic and resembles carbon and boron. Berzelius called it silicium or Kiesel. He first prepared pure boron chloride (chlorbundet boron) and analysed it (boron 9-257, chlorine 90 743). It was discovered independently by Dumas when his paper was published, Despretz produced evidence that he had discovered it in Jidy 1823, and Thomson regarded Despretz, Berzelius, and Dumas as independent discoverers. Berzelius made further investigations of fluoboric add (fluoborsyra) and its salts. ... 

Dissolve 46-5 g. (45-5 ml.) of aniUne in a mixture of 126 ml. of concentrated hydrochloric acid and 126 ml. of water contained in a 1-htre beaker. Cool to 0-5° in a bath of ice and salt, and add a solution of 36-5 g. of sodium nitrite in 75 ml. of water in small portions stir vigorously with a thermometer (1) and maintain the temperature below 10°, but preferably at about 5° by the addition of a httle crushed ice if necessary. The diazotisation is complete when a drop of the solution diluted with 3-4 drops of water gives an immediate blue colouration with potassium iodide - starch paper the test should be performed 3-4 minutes after the last addition of the nitrite solution. Prepare a solution of 76 g. of sodium fluoborate (2) in 150 ml. of water, cool, and add the chilled solution slowly to the diazonium salt solution the latter must be kept well stirred (1) and the temperature controlled so that it is below 10°. Allow to stand for 10 minutes with frequent stirring. Filter... 

Dissolve 34 g. of o-nitroaniline in a warm mixture of 63 ml. of concentrated hydrochloric acid and 63 ml. of water contained in a 600 ml. beaker. Place the beaker in an ice - salt bath, and cool to 0-5° whilst stirring mechanically the o-nitroaniline hydrochloride will separate in a finely-divided crystalline form. Add a cold solution of 18 g. of sodium nitrite in 40 ml. of water slowly and with stirring to an end point with potassium iodide - starch paper do not allow the temperature to rise above 5-7 . Introduce, whilst stirring vigorously, a solution of 40 g. of sodium borofluoride in 80 ml. of water. Stir for a further 10 minutes, and filter the solid diazonium fluoborate with suction on a sintered glass funnel. Wash it immediately once with 25 ml. of cold 5 per cent, sodium borofluoride solution, then twice with 15 ml. portions of rectified (or methylated) spirit and several times with ether in each washing stir... 

Dissolve 200 g. of sodium nitrite in 400 ml. of water in a 2-litre beaker provided with an efficient mechanical stirrer, and add 40 g. of copper powder (either the precipitated powder or copper bronze which has been washed with a little ether). Suspend the fluoborate in about 200 ml. of water and add it slowly to the well-stirred mixture. Add 4-5 ml. of ether from time to time to break the froth. The reaction is complete when all the diazonium compound has been added. Transfer the mixture to a large flask and steam distil until no more solid passes over (about 5 litres of distillate). Filter off" the crystalline solid in the steam distillate and dry upon filter paper in the air this o-dinitrobenzene (very pale yellow crystals) has m.p. 116° (t.c., is practically pure) and weighs 29 g. It may be recrystallised from alcohol the recrystallised solid melts at 116-5°. 

Phosphorus pentachloride, for conversion of pentaacetylgluconic add to add chloride, 41, 80 for oxidation of cycloheptatriene to tropylium fluoborate, 43, 101 with cyanoacetic acid, 41, 5 Phosphorus tribromide, reaction with 1.5-hexadien-3-ol, 41, 50 Phthalic anhydride, reaction with L-phenylalanine to yield N-phthalyl-L-phenylalanine, 40, 82 Phthalic monoperacid, 42, 77 N-Phthalyl-i.-alanine, 40, 84 N-Phthalyl-/3-alanine, 40, 84 N-Phthalylglycine, 40, 84 N-Phthalyl-l-/5-phenylalanine, 40, 82... 

For fluoboric acid preparation, to 200 ml 40% w/v hydrofluoric acid at 10°C, add, in small quantities, 75 g boric acid. Allow to dissolve and store in a polythene bottle. This reagent should be prepared freshly each day. 

Weigh 1.000 g of finely divided sample into a 250 ml beaker and cover with a watch glass. Add 40 ml of water, 6 ml of fluoboric acid and 12 ml of concentrated nitric acid. Warm the solution gently. Agitating the solution using a magnetic stirrer will aid dissolution. Cool to room temperature. Add 5 ml of 1% tartaric acid solution. Dilute to 100 ml with water. 

In a 25-mL Erlenmeyer flask place 8.75 mL of acetic anhydride, cool the tube, and add 0.44 g of fluoboric acid. Add 1 g of triphenylmethanol with thorough stirring. Warm the mixture to give a homogeneous dark solution of the triphenylmethyl fluoborate, then add 0.4 g of cycloheptatriene. The color of the trityl cation should fade during this reaction and the tropilium fluoborate begin to precipitate. Add 10 mL of anhydrous ether to the reaction tube, stir the contents well while cooling on ice, and collect the product by filtration on the Hirsch funnel. Wash the product with 10 mL of dry ether and then dry the product between sheets of filter paper. 

To the filtrate add 3 M sodium hydroxide solution and shake the flask to allow all of the acetic anhydride and fluoboric acid to react with the base. Test the aqueous layer with indicator paper to ascertain that neutralization is complete and then transfer the mixture to a reaction tube and draw off the aqueous layer. Wash the ether once with 10 mL of water, once with 10 mL of saturated sodium chloride solution, and dry the ether over anhydrous sodium sulfate, adding the drying agent until it no longer clumps together. 

The tropilium fluoborate can be converted to tropilium iodide by dissolving the borate in the minimum amount of hot, but not boiling, water (a few drops) and adding to this solution 1.25 mL of a saturated solution of sodium iodide. Cool the mixture in ice, remove the solvent with a pipette, and wash the crystals with 2.5 mL of ice-cold methanol. Scrape most of the crystals onto a piece of filter paper and allow them to dry before determining the weight. To the crystalline residue in the test tube add a few drops of water warm the tube, if necessary, to dissolve the tropilium iodide and then add a drop of 2% aqueous silver nitrate solution and note the result. 

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