Methyl 3,5-dimethylbenzoate

These rate constants are for the basic hydrolysis of methyl 4-substituted 2,6-dimethylbenzoates at 125°C in 60% dioxane. 

Plots of the left-hand side of these equations against X are curved, allowing easy distinction of an A2 mechanism. Excess acidity plots using equation (59) are shown for some ester hydrolyses in sulfuric acid at 25°C in Fig. 10, for 1-butyl acetate,29 and for methyl 2,6-dimethylbenzoate and methyl benzoate.41 The first ester (leftmost line in Fig. 10) clearly undergoes an A1 hydrolysis, specifically AAil 29 the parameters of the line are slope 1.552 + 0.027 intercept... 

Fig. 10 Excess acidity plots against X for the hydrolyses of some esters in aqueous H2SO4 at 25°C for methyl benzoate (open circles) and methyl 2,6-dimethylbenzoate (closed circles), data from ref. 41, and for r-butyl acetate (open triangles), data from ref. 29. PCT, protonation correction term.

Relatively stable 2,2,4,6-tetramethyl-2//-pyran (176) exhibited a high regiospecificity toward methyl propargylate to afford [47t + 27t] adduct 561, which spontaneously decomposed to methyl 2,4-dimethylbenzoate (562) in 73% yield.405 Similarly, labile 3-acetyl-2,6-dimethyl-2//-pyran (564) gave with acetylenic methyl carboxylates benzenoid derivatives 565. On the other... 

Substituent effects on the A,u I reaction have been studied by Bender and Chen55. These authors measured the rates of hydrolysis of a series of 4-substituted 2,6-dimethylbenzoates in 9.70 M sulphuric acid at 25°C, and found that the values for the first-order coefficients with 4-methoxy, 4-methyl, 4-unsubstituted and 4-bromo-compounds (5.0, 0.37, 0.033 and 0.01 x I0 4 sec-1, respectively) are satisfactorily correlated by the Hammett equation, following cr+ with a slope p = —3.22. Since the esters are not fully protonated in 9.70 M H2SOj, part of this factor is due to the effects of the 4-substituent on the protonation equilibrium, p for the protonation of substituted benzoic acids is about — l35, but is likely to be considerably smaller for di-ortho-substituted compounds, since the conjugative interaction of the p-substituents with the protonated carboxyl group requires coplanarity with the ring. 

This point is well-illustrated by the data of Table 19, which show the effect of methyl substituents on the rate coefficients for methyl ester formation from benzoic acid. The compounds fall naturally into three classes. Those with no ortho substituent react 3-4 times as fast as those which have one orthomethyl group, while 2,6-dimethylbenzoic acid, the only compound with two orf/io-substituents, did not give the ester at a measurable rate. 

Bromination of 2-methyl-,447, 481 7-methyl-,78,478 5-bromo-,76 2-fluoro-,482 or 2-phenylbenzo[6]thiophene483 in either chloroform or carbon tetrachloride gives the 3-bromo compound in each case. 2-(2-Naphthyl )benzo[6]thiophene is brominated,54 chlorinated, and iodinated484 in the 3-position. In the cases of 3-methyl-485 and 3-bromobenzo[6]thiophene,107 bromination takes place in the 2-position. Bromination of 2,3-dimethylbenzo[6]thiophene in dilute chloroform solution at 0° gives mainly nuclear substitution in the 6-position,81 but chlorination in acetic acid causes substitution in the 2-methyl group, to give 2-chloromethyl-3-methvlbenzo[6]thiophene.419... 

Bromomethylbenzo[6]thiophenes are readily obtained in high yields by treatment of the corresponding methyl compound with. V-bromosuccinimide in the presence of benzoyl peroxide.91,105,298 343,4i3,447,487,489-492,517,518 Applied to 3-methylbenzo[6]thiophene, this procedure affords 2-bromo-3-methylbenzo[6]thiophene (12%), in addition to the required product the yield of nuclear substituted product rises to 78% when peroxides are excluded.487 When 3,5-dimethylbenzo[6]thiophene is treated with W-bromosuccinimide, the 3-methyl group is preferentially brominated,489 but in the cases of other 5-alkyl-3-methylbenzo[6]thiophenes inseparable mixtures of products are formed.292 The above reaction has also been applied to... 

Nitration of 2,3-dimethylbenzo [ijthiophene unexpectedly gives 3-methyl-2-nitromethylbenzo[ ]thiophene as the major product (33%), together with 2,3-dimethyl-6-nitrobenzo[6]thiophene (10%),... 

MIPs were doped with Eu3+ for optical detection of methylated salicylates (MES), a chemical warfare agent simulant [55]. Eu3+ absorbs in the near UV region and doped MIP can, therefore, be excited with a commonly available laser diode at 375 nm. MIP doped with Eu3+ was prepared as a thin film on a quartz slide substrate. Both the MIP and NIP films were tested towards MES and a structurally similar compound, methylene-3,5-dimethylbenzoate (DMB), in hexane. For MES,... 

Another example is the reaction of benzyne with 1-methyl- (and benzyl)-3, 3-dimethylbenzo[d]-l,3-azasiloline (see their preparation in Section IV.A.2.p). Stevens rearrangement product is obtained (48%) as a single compound. If a Me on nitrogen is replaced by an Et, then Hoffmann elimination occurs.251 It should be noted that an Y-alkyl MSMA is converted into an Y-aryl RSMA in the former case and into a Y-aryl MSMA in the latter case. 

Alkylidenecarbenes 124, formed from alkynyliodonium salts 123 and 1-naphthol derivatives, undergo 1,6-C-H insertion at the />m"-position to yield bcnzo[z/ ]chromcncs 125 (Scheme 41) <2001TL6031>. The alkylidenecarbene formed from alkynyliodonium salt 123 and 2-methylnaphthalen-l-ol, can undergo 1,6-C-H insertion at both the /imposition and at the 2-methyl substituent, resulting in a 2 1 mixture of 2,9-dimethylbenzo[r/c ]chromcne and 2-methyl-4//-benzo[ ]chromene (Equation 59) <2001TL6031>. 

The limited space inside the H-Beta pores becomes apparent when 2-methyl and 2,6-dimethylbenzoic acid are applied as the reactants with resorcinol and compared to benzoic acid. With 2-methylbenzoic acid the conversion to the benzophenone is accelerated due to electronic effects, with 2,6-dimethylbenzoic acid the reaction slows down because the intermediate ester is too bulky to be formed inside in the pores. 65 66... 

The ease of oxidation in the presence of the CAB system with hydrogen peroxide is generally benzyl alcohols > aldehydes > toluenes. This series accounts for the reactivity and subsequent product distributions when 1,4-dimethybenzene is oxidized with the CAB system. Here, 4-methylbenzoic acid forms preferentially to attack at the second methyl group. Similarly, oxidation of 1,3,5-trimethylbenzene yields 3,5-dimethylbenzoic acid. This is complementary to the reactivity observed with the HBr/hydrogen peroxide/hv method (see... 

DIMETHYL-l. 3-BENZDIOXOL-4-YL-N-METHYL-CARBAMATE 2,2-DIMETHYLBENZO-l,3-DIOXOL-4-YL METHYLCARBAMATE 2,2-DIMETHYL-4-(N-METHYLAMINOCARBOXYLATO)-l,3-BENZODIOXOLE... 

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