Elimination aliases

Step 8 If necessary, add more runs to the design matrix to eliminate aliases or confounding patterns. For example, if a fractional factorial experiment shows evidence of interactions between variables, it may be necessary to run the full factorial to determine which interactions are truly important. 

Nitrations are usually carried out at comparatively low temperatures at higher temperatures there may be loss of material because of the oxidising action of the nitric acid. For substances which do not nitrate readily with a mixture of concentrated nitric and sulphuric acids ( mixed acid ), the intensity of the reaction may be increased inler alia by the use of fuming sulphuric acid (containing up to 60 per cent, of sulphur trioxide) or by fuming nitric acid. Thus nitrobenzene is converted by a mixture of fuming nitric acid and concentrated sulphuric acid into about 90 per cent, of wi-dinitrobenzene and small amounts of the o- and p-isomers the latter are eliminated in the process of recrystallisation ... 

A variety of ring syntheses have been devized which depend on carbanion addition to an activated double bond. The examples depicted in Scheme 74 illustrate the use of inter alia cyano and nitro groups which are subsequently eliminated. In appropriate instances the inclusion of additional eliminable groups ensures the formation of fully aromatized products. 

Ah initio calculations to map out the gas-phase activation free energy profiles of the reactions of trimethyl phosphate (TMP) (246) with three nucleophiles, HO, MeO and F have been carried out. The calculations revealed, inter alia, a novel activation free-energy pathway for HO attack on TMP in the gas phase in which initial addition at phosphorus is followed by pseudorotation and subsequent elimination with simultaneous intramolecular proton transfer. Ah initio calculations and continuum dielectric methods have been employed to map out the lowest activation free-energy profiles for the alkaline hydrolysis of a five-membered cyclic phosphate, methyl ethylene phosphate (247), its acyclic analogue, trimethyl phosphate (246), and its six-membered ring counterpart, methyl propylene phosphate (248). The rate-limiting step for the three reactions was found to be hydroxyl ion attack at the phosphorus atom of the triester. ... 

Aromatically bonded fluorine atoms are easily substituted via an addition-elimination mechanism inter alia by N-nucleophiles. Virtually every combination of fluoro-substituted aromatic substrate and nucleophile has been investigated a complete survey is beyond the scope of this section which focuses on selected topics. An excellent review has been published recently.120... 

There are several reports concerning the thermal and photochemical reactivity of triorganolead metal complexes. In general they eliminate plumbylenes, R2Pb, with a concurrent transfer of the organic radical to the metal center. Such chemistry is reported for platinum, iron and molybdenum inter alia. A typical reaction is outlined in equation 195484.494,507,509... 

Photolysis of ReCp (CO)3 in CeFe does not lead to the jj -CeFe complex. Instead, both C-H and C F activation take place leading inter alia to the fulvene complex Re(jj -C6Me5CH2)(CO)2(C6F5) and HF elimination (see Section 9). ... 

Now suppose c(jr,0) is the gamma distribution (,a,x). One can now eliminate c(x,t) between the equations to obtain an alias (Aris and Astarita, 1989a), an explicit relationship between —dCldt and C ... 

Vinylogous eliminations, in which both leaving groups depart from the same centre, are also known. The [l,A,4,(5)I]-elimination of ethylene from 94, which inter alia yields 95 (20 %)56) is typical. Here, the 2/3 double-bond is vinylogously shifted (A), while the 4/5 double-bond migrates under formation of a new single-bond (assistant figure for unequivocal classification). 

As expected, halogeno compounds also undergo [l,2,3]-eliminations (cf. footnote 68)). Thus, in the gas phase the dehydrochlorination of neopentyl chloride (59) inter alia yields the alkene 13142). From gem-dihalogen alkylcyclopropanes such as 132,... 

The structures and properties of quinone methides were recently reviewed . Inter alia, the microbial tyrosine phenol lyase (TPL) catalyzes the a, /3-elimination of L-tyrosine to phenol and ammonium pyruvate. It is assumed that the process includes three steps, the second of which is tautomerization of the aromatic moiety which converts it into a good leaving group (equation 49) °. 

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