Nitro--Cymene

Nitro-/>-cymene has always been secured by the nitration of the hydrocarbon, either by the use of mixed sulfuric and nitric acids with2 or without3 the addition of acetic acid, or by fuming nitric acid in acetic acid.4... 

Bisquaternary, as well as monoquaternary compounds and various amino derivatives, react with tetraphenylborate and similar compounds to form stable ion-pair complexes. TPSB was found to be very suitable as an ion-pairing agent for bisquaternary drugs with which it forms very insoluble compounds. The TPSB complexes were prepared in situ, by soaking the TPSB (potassium salt)/PVC membranes in the appropriate bisquaternary solution. Of the plasticizers tested, 2-nitrophenyloctyl ether (NPOE), dioctylphthalate, di-iso-butylphthalate, nitrobenzene, 2-nitro- -cymene, NPOE showed the best behavior in terms of response time and reproducibility. The membrane compositions were 3.2% (w/w) TPSB, 64.5% (w/w) NPOE and 32.3% (w/w) PVC. 

Commercial ISEs are made with liquid membranes involving both ion-exchanging systems and ionophores (see table 9.7). The solvent used is a hydrophobic liquid with a low relative permittivity. Examples include decane-l-ol, 5-phenyl pen tan-2-01, octyl phtalate, tri-n-phenyl phosphate, and 2-nitro-/ -cymene. Another important property of the solvent is that it have a low vapor pressure so that it is not... 

When -cymene was nitrated in the nucleophilic system ACONO2/AC2O, the product distribution was indeed different (below)i (3c) Subjection of the dienes to strong acid solvolysis gave exclusively 2-nitro- -cymene the total of 82% 2-nitro isomer thus obtained (41% direct + 41% ipso and solvolytic shift) nearly matched the 85% reported for N02 BFi." nitration. These results indicate that the previously unsuspected methyl position actually is the most reactive position toward nitration in -cymene. It was noted also that nitrodeisopropylation could not be avoided in AC2O no evidence was found for existence of a species contain-... 

The latest patent for the preparation of artificial thymol is that of E. M. Cole (U.S.P. 1,378,939, 24 May, 1921). His method consists essentially in the electrolytic reduction of nitro-cymene in the presence of sulphuric acid, and the subsequent diazotisation and reduction of the para-amidocymenol produced, by e ctric action, involving the use of stannous chloride. 

A current of density 5- amperes per square decimetre of cathode space and a potential of 3 volts is used, and the temperature is maintained at between 75° and 85° C. During the electrolytic action, the nitro-cymene is kept in thorough emulsion in the aqueous acid solution by means of the agitator. 

After the electrolytic action. has continued for a suitable period, the contents of the vessel are allowed to cool, following which the unchanged nitro-cymene is separated for re-use, and the l-methyl-2-amino-4-iso-propyl-5-hydroxy benzol is filtered off from the remaining acid solution, whidh latter is strengthened for re-use. The l-methyl-2-amino-4-isopropyl-5-hydroxy benzol is then diazotised, and further reduced in an alkaline solution of stannous chloride, in the usual and well-known manner, with the resulting- production of thymol (l-methyl-4-isopropyl-5-hydroxy benzol). 

Tisell Villaume (Ref 5) patented in 1918 a process for manufg expls by mixing nitrocymenes withO-carriers, to which may be added combustible substances silicons for raising the temp of expln, but not addg NC. One such mixt contd nitro cymene 15-20, NH4CI04 or NH4N03 70-80, ferro-silicon 5 10 woodmeal 1-5%... 

NiCo-phen) " in p-nitro-cymene tridodecyl-hexadecyl-ammonium nitrate in n-octyl-2-nitrophenyl ether... 

Nitro-m-xylene 2-Nitro-p-xylene 2-Nitro-p-cymene (4) Nitromesitylene... 

Fig. 3.4. Hydrophobic anion effect on ise- The membrane contains valinomycin with equivalent concentration of potassium tetraphenyl-borate dissolved in 2-nitro-p-cymene. - ise dependence on the activity of KCl o - f jgg dependence on the activity of KCIO4. The curves were calculated using equation (3.3.13). (After W. E. Morf, G. Kahr and W. Simon.)...

Fig. 7.1. Dependence of difference between standard Gibbs transfer energies on the logarithm of the selectivity coefficient for an ISE based on 2-nitro-p-cymene. (After Scholler and Simon [185].)...

As a rather strongly hydrophilic anion, nitrate requires an ISE membrane containing a strongly hydrophobic cation, as described on p. 169. This function was fulfilled in the first nitrate electrode from Orion Research by cation V [180] in nitro-p-cymene 5. The electrode can be used in the pH range 4-7. In other commercial electrodes, the ion-exchanger ion is a tetra-alkylammonium salt, for example in the electrode from Coming Co., substance XIII in solvent 6 [27]. An ISE with a renewable membrane surface was found to be very useful (see section 4.1 and fig. 4.4), in which the ion-exchanger solution contains the nitrate of crystal violet VII dissolved in nitrobenzene [191]. The NOj ISE also responds to nitrites that can be removed by addition of aminosulphonic acid. 

The fore-run, on refractionation at atmospheric pressure, yields 4-6 g. of impure />-cymene, b.p. 160-165°, and 10-13 g-of nitro compound. This latter amount is included in the total yields given in the procedure. 

The following nitrocymens are described in the literature. Of these, only the nitro derivs of p-cymene may be considered of interest at present because p-cymene is the only compd available icommercially... 

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