Elimination methyl

The electron impact mass spectrum of methyl isobutyrate, 27, contains a signal for a [M—CH3]+ ion. 2H- and 13C-labelling clearly establishes that the eliminated methyl radical originates exclusively from the intact PCH3 group (6)12,13,1 . 

From the reaction of imidazole 161 and aromatic acid halides (Scheme 63), imidoyl chlorides 162 are obtained, which eliminate methyl chloride to form imidazo[2,l-6]l,3,4]thiadiazoles 163 upon extended heating (88H1935). 

When trimethylorthoformate is utilized as the dehydration agent (Equation 8.), heavies due to Aldol condensation are eliminated. Methyl formate can be easily recovered from the reaction products, but synthetic routes to regenerate trimethylorthoformate are very involved and costly. An advancement to improve trimethylorthoformate synthesis would enhance the attractiveness of the homogeneous oxycarbonylation route to adipic acid. 

The checkers find that this wash eliminates methyl p-toluenesulfinate as a contaminant in the crude product. 

The reaction of sodium methoxide with isopropyl bromide will proceed mainly by elimination. Methyl bromide is prepared as shown previously sodium isopropoxide can be prepared by adding sodium to isopropyl alcohol. 

Methyl diphenyl telluronium benzoates slowly eliminated methyl benzoates9. 

Since straight chain alkanes rarely eliminate methyl groups (-CHj)... 

The rhodium(II) acetate decomposition of ketodiazoamides 296 in the presence dimethyl acetylenedicarboxylate generates intermediate bicyclic lactams 297, which eliminate methyl (or phenyl) isocyanate with the formation of furan derivatives (82-86%) 298 (89TL4077 91JOC820). Using the same route, substituted furans 299 have been obtained by the rhodium-... 

At the time of writing of the earlier article,1 compounds in this class had been prepared only from hexuronic acid derivatives by base- or enzyme-catalyzed eliminations methyl (methyl 4-deoxy-/3-L-threo-hex-4-enopyranosid)uronate (73), for example, had been pre-... 

Butadiene also eliminates methyl fluoride from methyldifluoro-... 

Hydriodic acid and phosphorus (22), like hydrochloric or hydrobromic acid replaces the hydroxyl of tropine by a halogen atom. The reductive elimination of this iodine atom from iodotropane by nascent hydrogen (Zn + HCl) provided the first preparation of the parent substance, tropane (dihydrotropidine) (I, R = CH3). (A more direct preparation of tropane is by the catalytic reduction of tropidine over platinum black (159a)). Tropane reacts readily with hydrogen chloride at an elevated temperature eliminating methyl chloride with the formation of a new saturated base, nortropane (94). The methyl group eliminated from tropane must have been attached to the nitrogen, for nortropane, in contrast to tropane, forms a well defined A-nitroso derivative. The isolation of methyl chloride and the secondary amine, nortropane, confirms the earlier assumption of the... 

Aside from the above-mentioned synthesis the best proof of the structure of stylopine is that of Spath and Posega (241), who reduced protopine to the carbinol, dehydrated this to the quaternary chloride, and then following Perkin s procedure eliminated methyl chloride by distillation in a high vacuum. The resulting product (LI) was identical with dl-tetrahydro-... 

The cyclic urea, 1,4,6-oxadiazocin-2-thione (73), can be methylated by treatment with methyl iodide either neat or in acetonitrile with potassium carbonate and 18-crown-6 <84S136>. The initially formed thiouronium salt undergoes thermolysis at 200°C to eliminate methyl iodide and yield the thiourea (74) in 60% overall yield (Scheme 7). 

US company Albemarle has been very much to the fore in the development of processes to reduce or eliminate risks associated with the production of BFRs. The middle of 1997 saw the completion of 3 years of research into a new process lliat eliminates methyl bromide, a highly regulated compound, as a by-product in the production of certain brominated compounds. Albemarle built a worldscale plant of 50,000 tormes in 1999 for the production of TBBPA at Magnolia, Arkansas that uses the new process. 

Details of the selective cleavage of o-glucuronidic linkages in saponins have been published (see Vol. 10, p. 117). A modified procedure for determining the sites of attachment of hexuronic acid residues in methylated acidic polysaccharides by base-catalysed degradation has been modelled on experiments with the methylated aldobiouronic acid derivative (430), which eliminated methyl 2,3,4-tri-O-methyl-p-D-glucopyranoside (89%) on treatment with sodium methylsulphinyl-methanide in DMSO at room temperature. When this procedure is applied to... 

Mercaptide Elimination. Kallio and Larson have described an oxidative degradation of methionine by a Pseudomonas. A pyridoxal phosphate enzyme eliminates methyl mercaptan and ammonia, leaving a-ketobutyrate. The methyl mercaptide is oxidized to dimethyl disulfide. 

A similar reaction of the heterocycle 168 with two equivalents of 4-methoxyphenyl isoselenocyanate affords the tetrazathiapentalene 170. The initially formed 1 1 cycloadduct 169 eliminates methyl isothiocyanate, followed by reaction with the second equivalent of... 

Other Reactions.— The compounds [PtX(CNMe)(PR3)2]+X can be demethylated by refluxing in benzene suspension this is the reverse of the standard alkylation of metal cyanides. The mechanism suggested, on somewhat meagre evidence, is halide attack at the platinum to give a five-co-ordinate intermediate which can eliminate methyl halide. Reaction of /ranj-[Pt(mesityl)(SnCls)(PEta)2] with nucleophiles, in 1,2-dichloroethane solution, proceeds by attack of the nucleophile at the tin rather than at the platinum. ... 

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