Methyl perchlorate, production

It was first prepd by treating xanthydrol with perchloric add in eth (Ref 3) or nitrobenzene (Ref 2). It has also been prepd by the oxidation of xanthene with triphenyl methyl perchlorate, and the product recrystd from acet to giver bronze plates (Ref 6) The refs consider the compd to be an expl... 

Treatment of 2-isoxazolines with acid usually leads to ring rupture and formation of chalcone products 62HC(l7)l), although 5-methyl-3-phenyl-2-isoxazoline forms a quaternary salt with dimethyl sulfate in the presence of perchloric acid (Scheme 51) (73BSF1390). 

Expulsion of nitrogen with formation of the A -l-methyl compound (9) occurs by heating (8) at ca. 220° or at room temperature by contact with acidic adsorbents. ° However, in this case perchloric acid or boron trifluoride etherate catalyzed fragmentation is not possible, although high yields (80 %) of (9) are obtained by heating (8) with quinoline or aniline. The la,2a-methylene compound (10) is always obtained as a by-product in 5% yield. 

Lukes studied the reaction of N-methyl lactams with Grignard reagents. With the five- (39-42) and six-membered (43-47) rings, 2,2-dialkylated bases (16, = 1,2) are formed as by-products in addition to the l-methyl-2-alkyl pyrrolines (15, = 1) or l-methyl-2-alkyl piperideines (15, =2). Aromatic Grignard reagents afford only the unsaturated bases, probably because of steric factors (48,49). Separation of enamines and 2,2-dialkylated amines from each other can be easily achieved since the perchlorates of the enamines and the picrates of 2,2-dialkylated bases crystallize readily. Therefore enamines can be isolated as crystalline perchlorates and the 2,2-dialkylated bases as crystalline picrates. Some authors who repeated the reactions isolated only pyrrolines (50,57) or, by contrast, 2,2-dialkylated bases (52). This can be explained by use of unsuitable isolation techniques by the authors. 

The excess of N-chlorosuccinimide is destroyed by the addition of about 15 drops of allyl alcohol and 180 ml of water is then added with stirring. This mixture is held at 0°C for about one hour. The precipitated 16/3-methyl-1,4-pregnadiene-9o-chloro-11/3,17o,21-triol-3,20-dione-21-acetate is recovered by filtration. A solution of 250 mg of the chlorohydrin in 5 ml of 0.25N perchloric acid in methanol is stirred for about 18 hours at room temperature to produce 16/3-methyl-9o-chloro-11/3,17o,21-trihydroxy-1,4-pregnadiene-3,20-dione which is recovered by adding water to the reaction mixture and allowing the product to crystallize. Propionic anhydride is then used to convert this material to the dipropionate. 

The purity of the product can be determined 3 6 by titration in glacial acetic acid, using perchloric acid (in glacial acetic acid) as titrant and methyl violet (0.2 g. of methyl violet in 100 ml. of chlorobenzene) as visual indicator (the first appearance of blue color is taken as the end point). 

Treatment of dibenzothiophene with alkyl halides in the presence of silver tetrafluoroborate or triaryloxonium tetrafiuoroborate has recently been shown to yield the corresponding 5-alkyl salts of type g0 96,359 Compounds thus prepared include 5-methyl- (93%), 5-ethyl-(98%), and 5-isopropyldibenzothiophenium tetrafiuoroborate (14%). The products were thermally unstable, reverting to dibenzothiophene, although the corresponding perchlorates were more stable. 5-Methoxy-... 

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