Alkyls methyls

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

Tertiary alkyl > secondary alkyl > primary alkyl > methyl... 

A related but distinct rhodium-catalyzed methyl acetate carbonylation to acetic anhydride (134) was commercialized by Eastman in 1983. Anhydrous conditions necessary to the Eastman acetic anhydride process require important modifications (24) to the process, including introduction of hydrogen to maintain the active [Rhl2(CO)2] catalyst and addition of lithium cation to activate the alkyl methyl group of methyl acetate toward nucleophilic attack by iodide. 

Oxidation. The use of l,4-ben2oquinone in combination with paHadium(Il) chloride converts terminal alkenes such as 1-hexene to alkyl methyl ketones in high yield (81%) (32). The quinone appears to reoxidi2e the palladium. 

Perylene Pigments. The perylenes ate a class of red and maroon pigments. In the general formula, Rmay represent a simple alkyl, methyl, or a substituted phenyl, eg, PR 123, R = p-ethoxyphenyl. 

Alkyl Methyl Carbonate ROCO2CH3 (Chart 2) Formation ... 

AIBt3, EtSH, 0°, 0.5-1 h, 73-78% yield. Aluminum bromide cleaves aryl and alkyl methyl ethers in high yield methyl esters are stable. 

Madsen and Lavvesson (6/), however, have reported recently that the treatment of /7-alkyl methyl ketones with morpholine in the presence of p-toluenesulfonic acid for a short period of time resulted in the formation of a mixture of condensation product of the ketone (122) and the corresponding dienamine (123). 

Similar results were encountered by Bianchetti et al. (i52), who found that e ketal derivatives of //-alkyl methyl ketones with morpholine led to the enamines of the condensation products of these ketones. The authors have Suggested the following probable mechanism for the dienamine formation. 

Me2Br, CH2CI2, 70°, 30-36 h, 72-96% yield." Alkyl methyl ethers are also cleaved, but tertiary methyl ethers are converted to the bromide. 

Buu-Hoi has shown that n-alkyl methyl ketones excluding ethyl methyl ketone, yield primarily 2-monosubstituted cinchoninic acids. It has been demonstrated that the products of the condensation of isatin with aryloxyketones are the corresponding 3-aryloxy-4-quinoline carboxylic acids rather than the isomeric 2-aryloxymethylcinchoninic acids.In the case of simple a-alkoxyketones such as 1-alkoxyethyl methylketones, the preferred products are the 2-alkoxyalkylcinchoninic... 

On the other hand, an electron-donating substituent destabilizes the 1-hydroxy-indole structure, often to the extent that it cannot be isolated. Even in such a case, alkylation of the 1-hydroxy group greatly improves the stability. Among alkylations, methylation is the best choice. This fact explains why every isolated natural product has a 1-methoxyindole structure (91YGK205, 99H1157). 

Numerous research activities have focused on the improvement of the protective films and the suppression of solvent cointercalation. Beside ethylene carbonate, significant improvements have been achieved with other film-forming electrolyte components such as C02 [156, 169-177], N20 [170, 177], S02 [155, 169, 177-179], S/ [170, 177, 180, 181], ethyl propyl carbonate [182], ethyl methyl carbonate [183, 184], and other asymmetric alkyl methyl carbonates [185], vinylpropylene carbonate [186], ethylene sulfite [187], S,S-dialkyl dithiocarbonates [188], vinylene carbonate [189], and chloroethylene carbonate [190-194] (which evolves C02 during reduction [195]). In many cases the suppression of solvent co-intercalation is due to the fact that the electrolyte components form effective SEI films already at potential which are positive relative to the potentials of solvent co-intercalation. An excess of DMC or DEC in the electrolyte inhibits PC co-intercalation into graphite, too [183]. 

Most of the above reactions are used for the cleavage of aryl sulphones. Recently, a note has appeared109 in which the use of potassium metal dispersed ultrasonically in toluene to cleave saturated cyclic sulphones is described. Addition of iodomethane permits the isolation of acyclic alkyl methyl sulphones (as outlined in equation (44)). 

Alkyl methacrylates Alkyl= Methyl (MMA) n-butyl, t-butyl (BuMA) Octyl Lauryl Octadecyl Phenyl Dimethylaminoethyl... 

By reaction of 2-alkyl-4,6-dichloro-l,3,5-trimethylborazines (alkyl = methyl, ethyl, i-propyl) with bis(trimethylsilyl)amine the tetrameric borazine ring systems 4-6 are produced (Fig. 2) they can be purified by several successive vacuum sublimations (yields 4-60%). If the borazines carry n-propyl and tert-butyl groups in the 2-position or if methylbis(trimethylsilyl)amine is used to bridge the borazine molecules, the macrocyclic ring formation is inhibited [17, 18]. 

Lewis acids are also used in conjunction with acyl halides. The reagent Nal—BF3 etherate selectively cleaves ethers in the order benzylic ethers > alkyl methyl ethers > aryl methyl ethers. 

Quenching of the same lithiated species with CO2, followed by reduction of the carboxyUc acid functionality obtained with BH3-THF complex, yielded the next higher analogues 78 to these alcohols [94]. Subsequent treatment of the depro-tonated alcohols with TsCl or MsCl afforded (l )-l-boranato[alkyl(methyl)plios-phino] ethanol-2-tosylates or the mesylate phosphine-boranes in over 90% ee and excellent overall yields. 

The reaction of alkyllithium reagents with diaryl or alkyl aryl sulphoxides results in a displacement of the aromatic group by the alkyl group from the alkyllithium (equation 369) . Johnson and coworkers ° were the first to apply this reaction for the synthesis of optically active alkyl methyl sulphoxides. Later on. Durst and coworkers found that the aromatic group which can best carry a negative charge is the most readily displaced, and that the lowest yields of displacement were observed when methyllithium was used as a nucleophilic reagent. The results are summarized in Table 28. 

In 2000, Woodward et al. reported that LiGaH4, in combination with the S/ 0-chelate, 2-hydroxy-2 -mercapto-1,1 -binaphthyl (MTBH2), formed an active catalyst for the asymmetric reduction of prochiral ketones with catecholborane as the hydride source (Scheme 10.65). The enantioface differentiation was on the basis of the steric requirements of the ketone substituents. Aryl w-alkyl ketones were reduced in enantioselectivities of 90-93% ee, whereas alkyl methyl ketones e.g. i-Pr, Cy, t-Bu) gave lower enantioselectivities of 60-72% ee. 

Oxime carbamates have high polarity and solubility in water and are relatively chemically and thermally unstable. They are relatively stable in weakly acidic to neutral media (pH 4-6) but unstable in strongly acidic and basic media. Rapid hydrolysis occurs in strongly basic aqueous solutions (pH > 9) to form the parent oxime/alcohol and methylamine, which is enhanced at elevated temperature. Additionally, oxime carbamates are, generally, stable in most organic solvents and readily soluble in acetone, methanol, acetonitrile, and ethyl acetate, with the exception of aliphatic hydrocarbons. Furthermore, most oxime carbamates contain an active -alkyl (methyl) moiety that can be easily oxidized to form the corresponding sulfoxide or sulfone metabolites. 

Figure 11.8 THM GC trace of bleached beeswax. FAME, fatty acid methyl ester obtained with a resistively heated filament pyrolyser at 550°C MeO FAME, methyl ester of methoxy fatty acid ME, alkyl methyl ether DiME, dimethoxyalkane EtC, hydrocarbon X Y, carbon chain length number of double bonds. Reprinted from J. Anal. Appl. Pyrol., 52, Asperger et al., 1, 13, Copyright 1999 with permission from Elsevier...

Unlike the reaction of alkyl aryl ketoximes with tetrasulfur tetranitride <1996CHEC-II(4)355>, the treatment of alkyl methyl ketoximes 189 with tetrasulfur tetranitride antimony pentachloride complex in either benzene or toluene at 50-80°C gave low yields (3-37%) of 3-alkyl-4-methyl-l,2,5-thiadiazoles 190 (Equation 39) <1999H(50)147>. Compounds 190 were volatile and the low yields are in part attributed to their loss as the solvent was removed in vacuo. Suprisingly, only single regioisomers were obtained. 3-Heptanone oxime 191 did, however, give a mixture of two isomers 192 and 193 (Equation 40). 

Most aliphatic ketones can lose a proton from either of two carbon atoms adjacent to the carbonyl. The question of which of the possible carbanions or salts is the effective reagent in a given base-catalyzed reaction depends on the nature of the electrophilic reagent with which the ion subsequently reacts. Thus alkyl methyl ketones lose a primary proton in their reactions with alkali and iodine, alkali and an aldehyde, or alkali and carbon dioxide, but lose a secondary proton in certain other reactions. 

In the condensation of alkyl methyl ketones with esters, the primary hydrogen is the one lost as in the reactions previously discussed with carbon dioxide, aldehydes, etc. The reaction is with the more rapidly formed and less hindered ion rather than with the ion that would be present in higher concentration at equilibrium. 

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