Acid Acetic Boric Anhydride

Reduction of sugars into alditols is effected by treatment with sodium borohydride, and acetylation by treatment with acetic anhydride containing sulphuric acid (2%) at 80°C for 15 h [436] or for 4 h by refluxing with a mixture of acetic anhydride and pyridine (1 1) [437]. The excess of reducing agent is usually decomposed prior to the acylation by treatment with an acid. The boric acid so produced should be removed, as it forms a complex with alditols and retards the acylation. Polar stationary phases (e.g., Carbowax 20M), on which strong sorption and decomposition of the derivatives occur, are not very suitable for the GC separation of acetates. Carbowax 20M modified with terephthalic acid and XE-60 provides good results, but some derivatives do not separate. 

The two acids which are commonly used as reaction solvents are formic and acetic acids. Formic acid (bp 101°) is usually obtained as an 85 to 90 per cent solution in water, which is satisfactory for most purposes such as the formation of performic acid and A2-methylform-anilides. It may be obtained anhydrous by drying over boric anhydride or 3 parts phthalic anhydride and distilling. Acidic drying... 

These precursors are prepared by reaction of fuming nitric acid in excess acetic anhydride at low temperatures with 2-furancarboxaldehyde [98-01-1] (furfural) or its diacetate (16) followed by treatment of an intermediate 2-acetoxy-2,5-dihydrofuran [63848-92-0] with pyridine (17). This process has been improved by the use of concentrated nitric acid (18,19), as well as catalytic amounts of phosphoms pentoxide, trichloride, and oxychloride (20), and sulfuric acid (21). Orthophosphoric acid, -toluenesulfonic acid, arsenic acid, boric acid, and stibonic acid, among others are useful additives for the nitration of furfural with acetyl nitrate. Hydrolysis of 5-nitro-2-furancarboxyaldehyde diacetate [92-55-7] with aqueous mineral acids provides the aldehyde which is suitable for use without additional purification. 

Traces of water have been removed by refluxing with tetraacetyl diborate (prepared by warming 1 part of boric acid with 5 parts (w/w) of acetic anhydride at 60, cooling, and filtering off), followed by distn [Eichelberger and La Mer J Am Chem Soc 55 3633 1933],... 

Acetic anhydride See Acetic anhydride Boric acid... 

The derivative 53 (m.p. 297-300 °C) has been prepared by heating the hydrazone 52 with 1 equiv of boric acid in hot acetic anhydride (Equation 2). No other derivatives were described <2003HCA1949>. 

Boron triacetate, B(OCOCH3)3. Mol. wt. 187.95. Supplier Alfa. Boron triacetate can be prepared by heating boric acid with excess acetic anhydride. It is generally less destructive than BF3 etherate. 

Borabicyclo[3.3.1Jnonane (9-BBN), 31 Boric acid, 32 2-Bornene, 419 Boronobenzoic acid, 32 Boron oxide, 32 Boron tribromide, 33-34 Boron trichloride, 34-35 Boron triiluoride etherate, 7, 9, 35-36, 40, 124, 160, 161, 182, 229, 230, 430, 438 Boron trifluoride etherate—Acetic anhydride, 36-37... 

Bobbitt, J. M., Periodate Oxidation of Carbohydrates, 11, 1—41 Boeseken, J., The Use of Boric Acid for the Determination of the Configuration of Carbohydrates, 4, 189-210 Bonner, T. G., Applications of Tiifluoro-acetic Anhydride in Carbohydrate Chemistry, 16, 59-84 Bonner, William A., Friedel-Crafts and Grignard Processes in the Carbohydrate Series, 6, 251-289 Bourne, E. J., and Peat, Stanley, The Methyl Ethers of n-Glucose, 6, 145-190... 

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