1.4- Dimethyl-2-nitrobenzene

Carboxy-, 5-dimethyl nitrobenzene, AP11 Carboxyferrocene, ATl6 2-Carboxy-3-hydroxy- -pyrone,... 

Table 10.12 lists the Ea of aromatic nitrocompounds determined by both the TCT and ECD methods. The values are the weighted averages. The ECD and TCT values agree within the uncertainty. They are confirmed by reduction potential data and CURES-EC calculations (not fisted). This is the largest number of Ea for related compounds that have been measured by any two techniques [15, 16, 63-68]. The ECD Ea for the dimethyl-nitrobenzenes, m-Cl-nitrobenzene, p-Cl-nitrobenzene, and 2-Cl-6-Me-nitrobenzene are not published elsewhere. The Ea for the dimethyl-nitrobenzenes are obtained from data in the linear region. Those for the chlorinated compounds are obtained from the fit to the data in both regions. The Ea for m-Cl-nitrobenzene is a lower limit because there are no data in the a region. These confirm the TCT values. 

Figure 10.12 Plots of ECD data as In KT3/2 versus 1,000/T for dimethyl-nitrobenzene. The data were determined with a concentric electrode Ni-63 detector using dibromobenzene as an internal standard. They were also collected along with the data in [15], but electron affinities were not obtained because of the structure.

Nitroalkanes are monoarylated effectively by using a biphenylphosphine and CS2CO3 as ligand and base, respectively (Eq. 27) [20, 72]. The intramolecular version has been reported [57]. Interestingly,4-nitrotoluene undergoes formal vinylogous arylation, while 3-nitrotoluene is inactive [73]. Thus, 3,4-dimethyl-nitrobenzene is selectively arylated at the 4-methyl group (Eq. 28). 

Strong acids and strong alkaUes can severely bum the skin, chromium compounds can produce skin rashes, and repeated exposure to solvents causes removal of natural oils from the skin. Infection is always a concern for damaged skin. Absorption through the skin is possible for materials that are appreciably soluble iu both water and oil, eg, nitrobenzene, aniline, and tetraethyllead. Other materials can be absorbed if first dissolved iu extremely good solvents, eg, dimethyl sulfoxide. Subcutaneous iujection can occur accidentally by direct exposure of the circulatory system to a chemical by means of a cut or scratch or iuadvertent penetration of the skin with a hypodermic needle. 

NOTE - Petrochemical plants also generate significant amounts of solid wastes and sludges, some of which may be considered hazardous because of the presence of toxic organics and heavy metals. Spent caustic and other hazardous wastes may be generated in significant quantities examples are distillation residues associated with units handling acetaldehyde, acetonitrile, benzyl chloride, carbon tetrachloride, cumene, phthallic anhydride, nitrobenzene, methyl ethyl pyridine, toluene diisocyanate, trichloroethane, trichloroethylene, perchloro-ethylene, aniline, chlorobenzenes, dimethyl hydrazine, ethylene dibromide, toluenediamine, epichlorohydrin, ethyl chloride, ethylene dichloride, and vinyl chloride. 

Although the uses of dimethyl sulfate and methyl toluene-p-sulfonate are well known, in many cases these reagents have been used in solution, e.g. in nitrobenzene, in addition to the older... 

The importance of the solvent, in many cases an excess of the quatemizing reagent, in the formation of heterocyclic salts was recognized early. The function of dielectric constants and other more detailed influences on quatemization are dealt with in Section VI, but a consideration of the subject from a preparative standpoint is presented here. Methanol and ethanol are used frequently as solvents, and acetone,chloroform, acetonitrile, nitrobenzene, and dimethyl-formamide have been used successfully. The last two solvents were among those considered by Coleman and Fuoss in their search for a suitable solvent for kinetic experiments both solvents gave rise to side reactions when used for the reaction of pyridine with i-butyl bromide. Their observation with nitrobenzene is unexpected, and no other workers have reported difficulties. However, tetramethylene sulfone, 2,4-dimethylsulfolane, ethylene and propylene carbonates, and salicylaldehyde were satisfactory, giving relatively rapid reactions and clean products. Ethylene dichloride, used quite frequently for Friedel-Crafts reactions, would be expected to be a useful solvent but has only recently been used for quatemization reactions. ... 

It is also interesting to note that quatemization of a chloropyrimi-dine at the nitrogen atom adjacent to the chloro group with methyl iodide results in the easy replacement of the chlorine by iodine, whereas similar salt formation on the remote nitrogen either leaves the chlorine unaffected or replacement occurs only at higher temperatures. A similar reaction occurs between 2-amino-6-chloro-4-methylpyrimidine and dimethyl sulfate in nitrobenzene to give the salt 45 and betaine 46. ... 

Caffeine (128) and dimethyl sulfate in nitrobenzene give the fully methylated dioxo compound 129. In the same way that 2,4-dialk-oxypyrimidines give unstable quaternary salts which decompose to the N-alkyl oxo compounds even at room temperature, the action of... 

Mixtures of 3//-azepines are also formed from l,2-dimethyl-4-nitrobenzene, which in diethyl-amine yields A,./V-diethyl-5,6-dimethyl-3//-a7cpin-2-amine (9%) and AfN-diethyl-4,5-dimeth-yl-3f/-azcpin-2-aminc (22% oxalate mp 119-120°C).66 Likewise, 2,4-dimethyl-l-nitrobenzene furnishes a mixture of /V.A-diethyl-5,7-dimethyl-3//-azepin-2-amine (7% oxalate mp 140-141UC) and /V,A-diethyl-3,5-dimethyl-3//-azepin-2-amine (2% oxalate mp 85-86 C). The symmetrically substituted l,3-dimethyl-5-nitrobenzene, as expected, yields only (V.tV-diethyl-4,6-dimethyl-3//-azepin-2-amine (46% bp 96 99 (2/1.3 Torr). 

Heteroaromatic diazonium salts can also be used for Gomberg-Bachmann aryla-tions. Fukata et al. (1973) refluxed 3,5-dimethyl-4-diazopyrazole (10.27) in benzene and obtained 3,5-dimethyl-4-phenylpyrazole (10.28, 36%), biphenyl (10.29, 17%), 3,5-dimethylpyrazole (10.30, 12%), and pyrazolo[4,3-c]pyrazole (10.31, 15%). In nitrobenzene the three isomeric 3,5-dimethyl-4-(nitrophenyl)-pyrazoles were formed in the ratio o m p = 10 3 3. In the opinion of Fukata et al. this ratio and the course of the reaction indicate a homolytic process. The present author thinks that the data do not exclude a competitive heterolytic reaction with the pyrazolyl cation, because equal amounts of substitution of nitrobenzene in the 3- and 4-positions are not typical for a homolytic aromatic substitution. 

Generally, higher catalyst concentration leads to side reactions. An efficient approach to minimize the side reactions is to use the minimum amounts of Friedel-Crafts catalyst (e.g., FeCl3, 0.1-4 wt%). The reaction can be performed either in bulk or in solution using, for example, nitrobenzene, dimethyl sulfone, or chlorinated biphenyls as the reaction media. 

Brown and McDonald (1966) provided another type of kinetic evidence for these size relationships by determining secondary kinetic isotope effects in reactions of pyridine-4-pyridines with alkyl iodides. For example, the isotopic rate ratio in the reaction between 4-(methyl-d3)-pyridine and methyl iodide at 25-0 C in nitrobenzene solution was determined to be kjyfk = l-OOl, while that in the corresponding reaction with 2,6-(dimethyl-d6)-pyridine was 1-095. (Brown and McDonald (1966) estimate an uncertainty of 1% in the k jk values.) Furthermore, the isotopic rate ratio in the case of the 2-(methyl-d3)-compound increased from 1 030 to 1-073 as the alkyl group in the alkyl iodide was changed from methyl to isopropyl, i.e. the isotope effect increased with increasing steric requirements of the alkyl iodide. 

Carbon monoxide cyanogen, hydrogen cyanide nitrites arsine aniline, dimethyl aniline, toluidine nitrobenzene hydrogen sulphide (causes respiratory paralysis by impairment of oxygen utilization in the central nervous system). 

Chloro-3- [(1 -ethoxycarbonyl-1 -methylethyl)amino] -4-nitrobenzene (61) gave 6-chloro-3,3-dimethyl-3,4-dihydro-2(l //)-quinoxalinone (62) (TiCl3, AcONa, HeO-MeOH, 20°C, 2.5 h >95%).1042... 

Parker37 defined class 4 as solvents "which cannot donate suitable labile hydrogen atoms to form strong hydrogen bonds with an appropriate species and proposed the designation dipolar aprotic solvents he extended their range down to s > 15 and quoted as examples acetone, acetonitrile, benzonitrile, dimethylformamide, dimethyl sulphoxide, nitrobenzene, nitromethane (41.8) and sulfolane (tetramethylene sulphone) (44), where e varies from 21 to 46.5, and the dipole moment p from 2.7 to 4.7 debye. 

The solvent dependence of the reaction rate is also consistent with this mechanistic scheme. Comparison of the rate constants for isomerizations of PCMT in chloroform and in nitrobenzene shows a small (ca. 40%) rate enhancement in the latter solvent. Simple electrostatic theory predicts that nucleophilic substitutions in which neutral reactants are converted to ionic products should be accelerated in polar solvents (23), so that a rate increase in nitrobenzene is to be expected. In fact, this effect is often very small (24). For example, Parker and co-workers (25) report that the S 2 reaction of methyl bromide and dimethyl sulfide is accelerated by only 50% on changing the solvent from 88% (w/w) methanol-water to N,N-dimethylacetamide (DMAc) at low ionic strength this is a far greater change in solvent properties than that investigated in the present work. Thus a small, positive dependence of reaction rate on solvent polarity is implicit in the sulfonium ion mechanism. 

The parent hexathiaadamantane (185) is obtained preparatively when a solution of formic acid and hydrochloric acid in nitrobenzene is allowed to stand for several weeks in a hydrogen sulfide atmosphere the product which separated is almost insoluble in all common solvents and purification presents a problem. Only large volumes of dimethyl sulfoxide at reflux serve for recrystallization.224 The reaction of thioacetic acid with formic acid in the presence of zinc chloride gives tetramethyl-(186), monomethyl-, dimethyl-and trimethylhexathiaadamantane derivatives (187).225 Other variations include the reaction of thioacetic acid with a /i-diketone,226 and the use of boron trifluoride227 or aluminum chloride as a catalyst.228... 

N,N-Dimethylacetamide (DMAc), 4-fluorobenzoic acid, 4-fluorobenzoyl chloride, aluminum chloride, 1 -bromonaphthalene, nitrobenzene, ferric chloride, dimethyl sulfone, 4,4 -dihydroxybiphenyl (DHB), and potassium carbonate were obtained from Aldrich and used without purification. 4,4-(Hexafluoroiso-propylidiene)-diphenol (6F-BPA), 9,9-bis(4-hydroxyphenyl)fluorene (HPF), and l,l-bis(4-hydroxyphenyl)-l-phenylethane (Bisphenol AP) were obtained from Ken Seika Corporation and used without purification. 4,4 -Dihydroxydiphenyl sulfone (DHDS) was obtained from Nachem Incorporated and used without purification. 

Menshutkin reaction between jV,Ar-dimethyl-d6-aniline and methyl tosylate in nitrobenzene at 51.3°C (21) is consistent with an inductive KIE resulting from the increased electron density on the nitrogen (the nucleophilicity), a steric explanation was preferred for three reasons. 

Dichloro-4-nitroaniline [99-30-9] 1,3-Dimethyl-2-nitrobenzene [81-20-9] 2609B 1(3)1194D, N(1)1146B ZE4686000, EPA... 

Gas), gas phase AQ, water MeOH, methanol EtOH, ethanol 2-PrOH, propan-2-ol EG, ethylene glycol DMSO, dimethyl sulphoxide AN, acetonitrile NB, nitrobenzene NM, nitromethane. 

Aluminium chloride, Nitrobenzene, 0062 Ammonium hydrogen sulfite, 4545 Benzyltriethylammonium permanganate, 3617 Bis(4-hydroxyphenyl) sulfone, 3497 2-Chloro-5-nitrobenzenesulfonic acid, 2144 1,3 -Dichloro-5,5-dimethyl-2,4-imidazolidindione, 1865 f Dimethyl sulfoxide, 0921... 

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