3.5- di-z-butyl

A mechanism involving an azatropilium cation has been discussed112 as a possibility for the observed ring contraction of 3,6- and 2,5-di-z-butyl-3//-azepines when these compounds are treated successively with bromine and aqueous K2CO3. 

Selective ring opening of benzofuran with lithium, in the presence of a catalytic amount of 4,4 -di( z/-butyl)diphenyl (TDBB), forms the (Z)-dilithiated species 72, which upon addition of a ketone or aldehyde forms 2//-chromenes (Scheme 24) <2001EJ02809>. 

Stoddart and co-workers have developed a variety of elegant stoppering strategies for dibenzylammonium-derived pseudorotaxanes. The 1,2,3-triazole stoppers present in [2]rotaxane 131 and [3]rotaxane 132 were generated by 1,3-dipolar cycloaddition reactions between bis(azidomethyl)-substituted cation and dication axles in the presence of di- z -butyl acetylenedicarboxylate <1996CEJ729, 1996TL6217>. 

Antioxidants are used to protect the finishes and the treated fibres from attack by oxygen and heat. Many antioxidants are used in rubber, plastic, composite, paint and coating/laminating materials. Hindered phenols are widely used as antioxidants, especially in the food industry. Two representative ones are butylated hydroxytoluene (BHT, 2,6-di-Z-butyl-4-methyl-phenol as shown in Fig. 5.9a) and butylated hydroxyanisole (BHA, a mixture of 2- and 3-Z-butyl-4-hydroxyanisole, shown in Fig. 5.9bl and b2, respectively). 

Oxidation inhibitors function by intermpting the hydroperoxide chain reaction. At temperatures up to ca 120°C, di-Z fZ-butyl- -cresol, 2-naphthol,... 

The susceptibihty of dialkyl peroxides to acids and bases depends on peroxide stmcture and the type and strength of the acid or base. In dilute aqueous sulfuric acid (<50%) di-Z fZ-butyl peroxide is resistant to reaction whereas in concentrated sulfuric acid this peroxide gradually forms polyisobutylene. In 50 wt % methanolic sulfuric acid, Z fZ-butyl methyl ether is produced in high yield (66). In acidic environments, unsymmetrical acychc alkyl aralkyl peroxides undergo carbon—oxygen fission, forming acychc alkyl hydroperoxides and aralkyl carbonium ions. The latter react with nucleophiles,... 

The following commercially available dialkyl peroxides are produced according to equations 24—27 di-Z fZ-butyl peroxide from hydrogen peroxide and sulfated tert-huty alcohol or isobutylene dicumyl peroxide from a-cumyl hydroperoxide and cumyl alcohol, cumyl chloride, and/or a-methylstyrene m- and -di(2-/ f2 -butylperoxyisopropyl)ben2ene [2781-00-2] from tert-huty hydroperoxide [75-91-2] and m- and -di(2-hydroxyisopropyl)ben2ene ... 

Concern for the conservation of energy and materials maintains high interest in catalytic and electrochemistry. Oxygen in the presence of metal catalysts is used in CUPROUS ION-CATALYZED OXIDATIVE CLEAVAGE OF AROMATIC o-DIAMINES BY OXYGEN (E,Z)-2,4-HEXADIENEDINITRILE and OXIDATION WITH BIS(SALI-CYLIDENE)ETHYLENEDIIMINOCOBALT(II) (SALCOMINE) 2,6-DI-important industrial method, is accomplished in a convenient lab-scale process in ALDEHYDES FROM OLEFINS CYCLOHEXANE-CARBOXALDEHYDE. An effective and useful electrochemical synthesis is illustrated in the procedure 3,3,6,6-TETRAMETHOXY-1,4-CYCLOHEX ADIENE. ... 

Lithium dimethyl and diphenylcuprates add to (phenylsulfonyl)acetylene with complete syn-stereoselectivity leading to -olefins 121. In the case of di-n-butyl and di-s-butylcuprates, 5-20% of Z-olefins 122 are also formed (equation 96)80. 

In an acetone extract from a neoprene/SBR hose compound, Lattimer et al. [92] distinguished dioctylph-thalate (m/z 390), di(r-octyl)diphenylamine (m/z 393), 1,3,5-tris(3,5-di-f-butyl-4-hydroxybenzyl)-isocyanurate m/z 783), hydrocarbon oil and a paraffin wax (numerous molecular ions in the m/z range of 200-500) by means of FD-MS. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out (Chapter 2). The method of Dinsmore and Smith [257], or a modification thereof, is normally used. Mass spectrometry (and other analytical techniques) is then used to characterise the various rubber fractions. The mass-spectral identification of numerous antioxidants (hindered phenols and aromatic amines, e.g. phenyl-/ -naphthyl-amine, 6-dodecyl-2,2,4-trimethyl-l,2-dihydroquinoline, butylated bisphenol-A, HPPD, poly-TMDQ, di-(t-octyl)diphenylamine) in rubber extracts by means of direct probe EI-MS with programmed heating, has been reported [252]. The main problem reported consisted of the numerous ions arising from hydrocarbon oil in the recipe. In older work, mass spectrometry has been used to qualitatively identify volatile AOs in sheet samples of SBR and rubber-type vulcanisates after extraction of the polymer with acetone [51,246]. 

Regio- and stereospecific 1,3-cycloaddition of di-tert-butylated acyl nitrone (548), generated in situ from (547), with Z-2-cyclodecanone and subsequent aromatization is the key step in the synthesis of biomimetic pyridomacrolidin... 

The iridium complex composed of l/2[ Ir(OMe)(cod)2 ] and 4,4 -di-/ r/-butyl-2,2 -bipyridine (dtbpy) shows a high catalytic activity for aromatic G-H silylation of arenes by l,2-di-/z r/-butyl-l,l,2,2,-tetrafluorodisilane.142 The reaction of 1,2-dimethylbenzene with l,2-di-/< r/-butyl-l,l,2,2,-tetrafluorodisilane in the presence of l/2[ Ir(OMe)(cod)2 ] and dtbpy gives 4-silyl-l,2-dimethylbenzene in 99% yield (Equation (103)), which can be utilized for other functionalizations such as arylation and alkylation. 

Experimental results [1361] and theoretical treatment [28] indicate that the cyclo-propanation of alkenes by electrophilic carbene complexes is a concerted process. Z-Olefins normally lead to the formation of the corresponding c7. -cyclopropanes, and -olefins yield fran -cyclopropanes. The relative configuration of the carbene-bound substituent and the substituents of the alkene in the final cyclopropane seems to be mainly determined by the steric bulk of these groups. In cyclopropanations of terminal alkenes with ethyl diazoacetate low diastereoselectivities are often observed [1024,1351]. These can be improved by increasing the steric demand of the substituents at the carbene or at the alkene [1033,1362]. High diastereoselectivities can, e.g., often be achieved with terf-butyl, neopentyl or 2,6-di(rerr-butyl)phenyl diazoacetate [1362] as carbene complex precursors (Figure 4.19). 

R = 2,6-(di-fert-butyl)-4-methyl-phenyl Scheme 9.3 Allylic substitution at a (Z)-allylic substrate. 

Chen J, Fiu H, Qiu Z, Shu W (2008) Analysis of di-n-butyl phthalate and other organic pollutants in Chongqing women undergoing parturition. Environ Pollut 156 849-853... 

In contrast, the Z isomer was attained as the major isomer (80-93%) by the anti addition of the Zweifel reagent [lithium di(isobutyl)- -butyl aluminate hydride] to the thioacetylene foUowed by trapping of the intermediate with BuTeBr. 

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