1.2.4.5- Tetra methyl-benzene

Above diffraction patterns of (a) mask representing molecule of durene, 1,2,4,5 tetra-methyl benzene, (6) the same ma k with an extra hole at the centre positive regions are strengthened, negative regions weakened. (Lipson and Cochran, 1953.) Below diffraction patterns of (c) the centrosymmetric arrangement of holes shown inset, and (d) the non-centrosymmetric arrangement of holes shown inset (C. A. Taylor, 1952)... 

DinitTO-l,3-(diamino-N,N,N, N -tetra-methyl)-benzene, yel nds (from chlf + ale), mp 191° sol in chlf si sol in hot ale was prepd by heating l,3-dinitro-4,6-dichlorobenzene with dimethylaniline in ale or from 2,4-dinitro-5-chloro-N,N- iimethylani-line 8c NH(CH3)2 (Ref 2)... 

Durene is the i-2-4-5-tetra-methyl benzene. It has a camphor-like odor and is found in coal tar. It can be made from one of the di-brom meta-xylenes, viz., the i-3-di-methyl 4-6-di-brom benzene by Fit-tig s qmthesis. 

X, X-Dinitro-1,3-( diamino-N, N, -tetra-methyl)-benzene, crysts (from dil ale or glac AcOH) was obtd by nitration of N,N,N, N -tetramethyl-phenelene-1,3-diamine using dil H2SO4 HNO3 (Ref 1)... 

Cross-alkylations have been reported on a number of occasions. Thus, ethylbenzene when treated with aluminium bromide and hydrogen bromide at 0 °C forms some benzene and diethylbenzene168, and in the sulphonation of durene some trimethyl- and pentamethyl-benzenesulphonic acids are formed as well as the tetra-methyl compound. It has been suggested169 that these transfer reactions involve an SN2 type process... 

Catyone( l-Methyl-2-oxy 4-isopropylene-h -tetra-hydro-benzene or 6,8 p-menthadien-2 one),... 

The photolysis of phenylethynylpentamethyldisilane (56) takes place simultaneously by at least two different processes. The main route proceeds through a silacyclopropene and the other involves transient formation of a silapropadiene. Irradiation of a benzene solution of 56 in the presence of acetone gives four products, 2,2,5,5-tetrameth-yl-3-trimethylsilyl-4-phenyl-l-oxa-2-silacyclo-3-pentene (57), 2,2,5,5-tetra-methyl-3-phenyl-4-trimethylsilyl- l-oxa-2-silacyclo-3-pentene (58), phen-yltrimethylsilylacetylene, and 1-pheny 1-1 -trimethylsily 1-3-methyl-1,2-butadiene (59), in 51,2,10, and 5% yield, respectively, with 81% conversion, of the starting disilane. The formation of 57 and 58 can be explained by insertion of acetone into the silacyclopropene. Liberation of dimethylsilyl-ene species from either direct photolysis of 56 or decomposition of the silacyclopropene results in the formation of PhC=CSiMe3. Product 59... 

Michler s Ketone.—similar di-amino compound in which two amino groups are substituted in benzophenone in the para position in each of the benzene rings yields a tetra-methyl amino product which is known as Michler s ketone. 

But in this connection the reaction is in many cases, and indeed in the simplest case, not of equal importance with its application for the ketone syntheses, for three reasons First, the product of the reaction is a hydrocarbon which can again react thus it is often difficult to limit the reaction to the desired point- For example, in the action of methyl chloride on toluene, not only is one hydrogen atom substituted, with the formation of dimethyl benzene, but varying quantities of tri-, tetra-, penta-, and hexa-methyl benzene are also formed. A second disadvantage is this In the different series a mixture of isomers is obtained in the above case, e.g., not only one of the three dimethyl benzenes, but a mixture of the 0-, m-, and p-varieties is formed, which cannot be separated like the homologues by fractional distillation. The reaction is still further complicated in that the aluminium chloride partially splits off the alkyl groups ... 

The phenomenon of complete electron transfer in solution is best illustrated with the now classic example of the NjNjN jN -tetra-methyl-p-phenylenediamine (TMPD)-chloranil reaction (Kainer and Wherle, 1955 Isenberg and Baird, 1962 Eastman et al., 1962). This pair forms a charge-transfer complex in solvents of low dielectric (e.g. dioxan, benzene, 1,2-dichlorethane) without complete electron transfer, whereas in acetonitrile the detectable, first-formed complex gives way to the separate cation and anion radicals, each of which is detectable by absorption and esr spectroscopy. 

The approximative modelling of methylbenzenium ions by benzene derivatives containing an extra substituent as compared with the respective methylated benzene was pointed out in the Raman spectraas well. Thus, the Raman spectrum of the mesitylenium ion in the region of 4tetra-substituted benzenes. 

The synthesis of 3-arm P2VP stars using l,3,5-tri(chloro-methyl)benzene, as well as the synthesis of 4-arm poly (tert-butylmethaciylate) (PtBuMA), poly(methyl methacrylate) (PMMA), and P2VP stars using l,2,4,5-tetra(bromomethyl)ben-zene, was reported (Scheme 9). Combined characterization results revealed that the use of bromo- instead of chloro-deiivatives and low temperatures leads to well-defined products. 

Photolysis of l-chloro-2,2,5,5-tetra-methyl-4-oxoimidazolidine/ Benzene... 

More recently Veening and coworkers have reported the gas chromatographic separation and determination of ring isometric methyl-benzene tricarbonylchromium complexes such as di, tri, and tetra-methylbenzene tricarbonylchromium. 

Hexakis(6-deoxy-6-iodo-2,3-di-0-methyl) a-cyclodextrin, on treatment with alkoxides and aryloxides, gave products derived by nucleophilic displacements of the iodide at five residues and elimination of hydrogen iodide to give the 6-deoxy-5-ene function at the sixth residue. P-Cyclodextrin was converted to the per-3-thio-D-altro analogue and then treated with the tetra-substituted benzene 37 to give the compound 38 which contains four cyclodextrin units and forms a 1 1 complex with tetraarylporphyrins. Disulfides, produced by linking monothio-cyclodextrin, have been described and include the 6,6-dimer, which is known, and the new 3,3- and 3,6-linked dimers. ... 

Estrone methyl ether (100 g, 0.35 mole) is mixed with 100 ml of absolute ethanol, 100 ml of benzene and 200 ml of triethyl orthoformate. Concentrated sulfuric acid (1.55 ml) is added and the mixture is stirred at room temperature for 2 hr. The mixture is then made alkaline by the addition of excess tetra-methylguanidine (ca. 4 ml) and the organic solvents are removed. The residue is dissolved in heptane and the solution is filtered through Celite to prevent emulsions in the following extraction. The solution is then washed threetimes with 500 ml of 10 % sodium hydroxide solution in methanol to remove excess triethyl orthoformate, which would interfere with the Birch reduction solvent system. The heptane solution is dried over sodium sulfate and the solvent is removed. The residue is satisfactory for the Birch reduction step. Infrared analysis shows that the material contains 1.3-1.5% of estrone methyl ether. The pure ketal may be obtained by crystallization from anhydrous ethanol, mp 99-100°. Acidification of the methanolic sodium hydroxide washes affords 10-12 g of recovered estrone methyl ether. 

---