From Allene

Figure A.2 Cash-flow pattern for a typical project. (From Allen, IChemE, 1980 reproduced by permission of the Institution of Chemical Engineers.)...

Fig. 6.21 The construction of a system of periodic cells in the Ewald method. (Figure adapted from Allen M P and D ] Tildesley 1987. Computer Simulation of Liquids, Oxford, Oxford University Press.)...

The anions derived from allenic sulfides, RCH=C=C-SR , which are stable in liquid... 

Extracts from Clavularia viridis and also many other coral species convert arachidonic acid to the prostanoidpreclavulone-A via 8-( f )-hydroperoxy-5,ll,14( Z), QfEj-eicosatetraenoic acid. The carbocyclization is considered to occur from allene oxide and oxidopentadienyl cation intermediates. An enantioselective total synthesis of preclavulone-A was developed to assist the biosynthetic research. 

Tlie thioketone 5-oxide 85, generated from allene 86 and SOCk in situ, decomposes to give the alkene 87. A mechanism, involving the transient formation of the 1,2-dithietane 88 (by dimerization of 85 followed by rearrangement), was proposed (85AGE855). 

Vinylepoxides from Other Substrates 9.1.5.1 From Allenes... 

Toda, F. Tanaka, K. Stein, Z. Goldberg, 1. Acta Crystallogn, Sec. C, 1996, 52, 177. Except where noted, values are from Allen, F.H. et al.. Ref. 52. In this source, values are given to three significant figures. 

From allenic substrates, with organocopper reagents... 

The method developed for the assembly of 2-166 has a broad scope. Scheme 2.39 shows a variety of differently C-3-substituted cephalosporins obtained from allene 2-164 in yields ranging from 68% to 95%. 

Figure 23 Fluorescence excitation and emission spectra, (a) virgin EVA sample (excitation = 280 nm emission = 360 nm) (b) EVA sample degraded for lh at 180°C (excitation = 239 nm emission = 390 nm) (c) EVA sample degraded for 1 h at 180°C (excitaton = 301 nm emission = 361 nm) (d) EVA sample degraded for 2 h at 180°C (excitation = 238 nm emission = 388 nm). Reprinted from Allen [67]. Copyright 2000, with permission from Elsevier. (This figure has been reproduced from the original in reference [67], however it would appear that the labels excitation and emission have been incorrectly inserted and should be switched for parts (b), (c) and (d).)...

Table 10.4 lists the values of trap density and binding energy obtained in the quasi-ballistic model for different hydrocarbon liquids by matching the calculated mobility with experimental determination at one temperature. The experimental data have been taken from Allen (1976) and Tabata et ah, (1991). In all cases, the computed activation energy slightly exceeds the experimental value, and typically for n-hexane, 0/Eac = 0.89. Some other details of calculation will be found in Mozumder (1995a). It is noteworthy that in low-mobility liquids ballistic motion predominates. Its effect on the mobility in n-hexane is 1.74 times greater than that of diffusive trap-controlled motion. As yet, there has been no calculation of the field dependence of electron mobility in the quasi-ballistic model. 

Figure 3.89 Cyclic voltammograms of 500 pm cytochrome c at a gold electrode modified by (a) 2-mercaptopyridine, (b> 2-mercaptosuccinic acid, 4,4 -dithiobis(butanoic acid), (d) 4-mercaploaniline. pH 7.0 phosphate buffer +0.1 M NaC104. Scan rale 50mVs . From Allen...

Figure 3.90 Structures and proposed surface conformations of the class IV modifiers (for details see text). From Allen el al. (1984).

Figure 10.7 (a) In HAD enzymes Asp mediates phosphoryl group transfer to a variety of acceptors, including H20 (b) the catalytic scaffold around the essential Mg2+ion. (From Allen and Dunaway-Mariano, 2004. Copyright 2004, with permission from Elsevier.)... 

Cylizations to numerous functionalized five-membered ring systems starting from allenes have recently been described in most cases they make use of Pauson-Kand or other metal-mediated ring-forming protocols (see Chapter 16 for a discussion of these useful cyclizations) [150]. 

Some cases are known in which Diels-Alder reactions of electron-deficient allenes and dienes compete with [2 + 2]-cycloadditions (see also Section 7.3.7) [12, 151, 335, 336]. Recently, a phosphane-catalyzed [4 + 2]-annulation starting from allenic ester 337 and N-tosylaldimines 338 was published [337]. However, the formation of the tetrahydropyridines 339 isolated in excellent yields is explained by a multi-step mechanism and only resembles a Diels-Alder reaction. 

The cydoaddition of different 1,3-dipoles such as azides [331, 341] and diazoalkanes [342-344] to acceptor-substituted allenes was thoroughly investigated early and has been summarized in a comprehensive review by Broggini and Zecchi [345], The primary products of the 1,3-dipolar cycloadditions often undergo subsequent fast rearrangements, for example tautomerism to yield aromatic compounds. For instance, the five-membered heterocycles 359, generated regioselectively from allenes 357 and diazoalkanes 358, isomerize to the pyrazoles 360 (Scheme 7.50) [331]. 

Palladium(II) is one of the most important transition metals in catalytic oxidations of allenes [1], Scheme 17.1 shows the most common reactions. Transformations involving oxidative addition of palladium(O) to aryl and vinyl halides do not afford an oxidized product and are discussed in previous chapters. The mechanistically very similar reactions, initiated by nucleophilic attack by bromide ion on a (jt-allene)pal-ladium(II) complex, do afford products with higher oxidation state and are discussed below. These reactions proceed via a fairly stable (jt-allyl)palladium intermediate. Mechanistically, the reaction involves three discrete steps (1) generation of the jt-allyl complex from allene, halide ion and palladium(II) [2] (2) occasional isomeriza-... 

Only a few isolated allene oxides have been synthesized from allenes and characterized. Most often peracids are used but the oxidative and acidic conditions usually result in a complex mixture of products. To overcome this problem, dimethyldioxirane (DMDO) can be used, which rapidly oxidizes allenes to spirodiepoxides. Several synthetically useful methods have been developed via in situ reaction of the intermediate allene oxide or spirodioxide with different nucleophiles. 

FIGURE 4.6 Effect of solid-state enzyme treatment on hypolipidemic activities of psyllium. Plasma lipid concentrations in hamsters were measured at day 35. Values are mean SEM (vertical bars) for nine animals per group. Within each response parameter, values not sharing common letters are significantly different, P<0.05. Modified Psy-1 and modified Psy-2 represent the two modified psyllium preparations using the Viscozyme L and the Shearzyme 500 L, respectively, under the solid-state reaction conditions (re-drawn from Allen et al., 2004). 

Fig. 39. Activity coefficients calculated from the data of Fig. 37 and from an additional set of data obtained from a duplicate run compared with the Gibbs-Duhem equation. Reprinted with permission from Allen, T. M., Taflin, D. C, and Davis, E. J., Ind. Eng. Chem. Res. 29, 682-690, Copyright 1990, American Chemical Society.

Flypothetical interactions of a five-subsite enzyme with a maltotetraose substrate shown initially with a terminally radiolabeled (filled circles) nonreducing end. The vertical arrow indicates the glycosyl bond cleavage region the roman numerals indicate the subsites, and the 4 indicates the chain length. Only three binding interactions lead to hydrolysis IV,4 V,4 and Vl,4, and their different associated rate constants emphasize that the rates of hydrolysis need not be identical. From Allen and Thoma with permission of the Biochemical Society (London). 

Similarly, the oxidation of iodocyclohexane by DMD under a nitrogen-gas atmosphere leads to the iodohydrin and diol as unexpected products (equation 24). The iodohydrin, formed as the major product, clearly reveals that hypoiodous acid (HOI) is generated in situ, which adds to the liberated cyclohexene. Indeed, when methyl iodide (Mel) is oxidized by DMD at subambient temperature in the presence of cyclohexene, the corresponding iodohydrin is obtained in very good yield The latter method may be utilized for the preparation of allylic alcohols with a vinylic iodo functional group from allenes (equation 25) . ... 

FIGURE 11.63 TEM images of an NaCl crystal (A) before reaction and (B) after reaction with gaseous HNO, (1.2 x 1015 cm-3 for 15 min) and then (C) exposure to water vapor (< 15 Torr) followed by drying (adapted from Allen et al., 1996). 

FIGURE 11.64 Energy-dispersive spectroscopy light-element spectra acquired from (a) one of the small microcrystallites attached to NaCl after exposure to gaseous HNO, (see Fig. 11.630 and (b) an adjacent area of the NaCl crystal (adapted from Allen et al., 1996). 

TABLE 5. Preparation of allenylzinc chloride reagents from allenes... 

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