Benzophenone, structure

Benzophenone, structure of, 697 Benzoquinone, electrostatic potential map of, 631 Benzoyl group, 697 Benzoyl peroxide, ethylene... 

The data in Figures 23 and 24 clearly show that the efficiency of the BP-TAA as a polymerization initiator couple depends on both the benzophenone structure and the structure of the tertiary amine. Since the trend observed in Figure 24 is characteristic for kinetic phenomena in what is known as the inverted Marcus region [12-14, 110, 111], and since benzophenone triplet quenching cannot display this specific kinetic phenomena, one concludes that the rate of polymerization photoinitiated by... 

Besides other linear polycondensates, poly(ester-imide)s with benzophenone structures were claimed [273] as useful for producing photographic images by exposure through a photographic mask. The varnishes were dried at 80 °C, giving on a copper substrata a 1.2 my layer. Exposure is made with a 1000 W UV lamp. The exposed areas, crosslinked by benzophenone hydrogen abstraction, are insoluble and the unexposed areas of the film are removed with N-methyl-pyrrolidone. 

An interesting sulfonamide diuretic that has little resemblance structurally to the thiazides is chlorthalidone, a benzophenone derivative. On a dose basis, it has an activity comparable to hydrochlorothiazide but is a much stronger carbonic anhydrase inhibitor than the thiazides, approximately 40 times sulfanilamide. Physical data indicate this compound to have the isoindoline structure rather than the benzophenone structure, I. The outstanding feature of this drug is its long duration of action, up to 72 hours (22, 32, 66). 

Figure 8.9 Rice husk/benzophenone structure after Gibbs free energy.

The benzene and benzophenone structure makes the acromolecular chains rigid, and ether linkages make the macromolecular chains flexible. Thus, PEEK is an engineering thermoplastic with both rigidity and flexibility. 

In this method, radicals generated by the UV exposure connect to other parts of molecules and generate a new structure. If this type of material shows a preferred photoalignment, then this new structure can be used to align the LC. This type of photoalignment was found in the benzophenone structured polyimide shown in Fig. 3.9 [32]. 

Two classes of charged radicals derived from ketones have been well studied. Ketyls are radical anions formed by one-electron reduction of carbonyl compounds. The formation of the benzophenone radical anion by reduction with sodium metal is an example. This radical anion is deep blue in color and is veiy reactive toward both oxygen and protons. Many detailed studies on the structure and spectral properties of this and related radical anions have been carried out. A common chemical reaction of the ketyl radicals is coupling to form a diamagnetic dianion. This occurs reversibly for simple aromatic ketyls. The dimerization is promoted by protonation of one or both of the ketyls because the electrostatic repulsion is then removed. The coupling process leads to reductive dimerization of carbonyl compounds, a reaction that will be discussed in detail in Section 5.5.3 of Part B. 

The intermediate diphenylhydroxymethyl radical has been detected after generation by flash photolysis. Photolysis of benzophenone in benzene solution containing potential hydrogen donors results in the formation of two intermediates that are detectable, and their rates of decay have been measured. One intermediate is the PhjCOH radical. It disappears by combination with another radical in a second-order process. A much shorter-lived species disappears with first-order kinetics in the presence of excess amounts of various hydrogen donors. The pseudo-first-order rate constants vary with the structure of the donor with 2,2-diphenylethanol, for example, k = 2 x 10 s . The rate is much less with poorer hydrogen-atom donors. The rapidly reacting intermediate is the triplet excited state of benzophenone. 

Ultraviolet absorptions ofvinylogous lactams were found by MOLCAO calculations and compared with experimental values (663). Infrared spectroscopic studies of vinylogous amides (664) and some fifty vinylogous urethanes (665) allowed configurational and structural assignments. The effect of enamine-imine equilibrium in a series of benzophenone derivatives was established (666) and the effect of structure on enamine basicity studied (667). 

Finally, examine transition states for cyanide addition cyanide+formaldehyde, cyanide+acetone, cyanide+ benzophenone) What relationship, if any, is there between the length of the forming CC bond and the various carbonyl properties determined above Try to rationalize what you find, and see if there are other structural variations that can be correlated with carbonyl reactivity. 

Quinazoline 3-oxides were first prepared by Awers and von Meyen-burg in 1891 by the dehydration of o-acylamino benzophenone oximes with acetic acid-acetic anhydride and were assigned the in-dazole structure (33). This was then modified by Bischler to the... 

The Ullman reaction has long been known as a method for the synthesis of aromatic ethers by the reaction of a phenol with an aromatic halide in the presence of a copper compound as a catalyst. It is a variation on the nucleophilic substitution reaction since a phenolic salt reacts with the halide. Nonactivated aromatic halides can be used in the synthesis of poly(arylene edier)s, dius providing a way of obtaining structures not available by the conventional nucleophilic route. The ease of halogen displacement was found to be the reverse of that observed for activated nucleophilic substitution reaction, that is, I > Br > Cl F. The polymerizations are conducted in benzophenone with a cuprous chloride-pyridine complex as a catalyst. Bromine compounds are the favored reactants.53,124 127 Poly(arylene ether)s have been prepared by Ullman coupling of bisphenols and... 

Glucose, benzophenone (C6HsCOC6H5), and methane are examples of compounds that form molecular solids. The structures of glucose and benzophenone are given here. 

As already shown, it is technically possible to incorporate additive functional groups within the structure of a polymer itself, thus dispensing with easily extractable small-molecular additives. However, the various attempts of incorporation of additive functionalities into the polymer chain, by copolymerisation or free radical initiated grafting, have not yet led to widespread practical use, mainly for economical reasons. Many macromolecular stabiliser-functionalised systems and reactive stabiliser-functionalised monomers have been described (cf. ref. [576]). Examples are bound-in chromophores, e.g. the benzotriazole moiety incorporated into polymers [577,578], but also copolymerisation with special monomers containing an inhibitor structural unit, leading to the incorporation of the antioxidant into the polymer chain. Copolymers of styrene and benzophenone-type UV stabilisers have been described [579]. Chemical combination of an antioxidant with the polymer leads to a high degree of resistance to (oil) extraction. 

Figure 7.39 Structural assignments of a benzophenone derivative based on low- and high-resolution mass spectrometry. After Squirrell [258], From D.C.M. Squirrell, Analyst, 106, 1042-1056 (1981). Reproduced by permission of The Royal Society of Chemistry...

Figure 8.20 (A) Generic chemical structure of the y-secretase inhibitors described by Seiffert et al. (2000). (B) y-Secretase inhibitor incorporating a benzophenone photoaffinity label for crosslinking studies.

When the steric size of the substituents increases, no adducts with bulky (Et3N) or less basic (EtzO) donors are formed with (Me3C)2Si= NSi(CMe3)3.14 The structure of the benzophenone adduct is quite remarkable.16 Instead of the expected cycloaddition product, the carbonyl oxygen atom is coordinated to the undersaturated silicon atom. 

Pt(en)(N03)2] and [Pt(OTf)2L2] (L = mono- or 1/2 bidentate tertiary phosphine) or dinuclear complexes of the type [Pt2(OTf)2(/i-monodentate tertiary phosphine cr-aryl = 4, -biphenyl, / -terphenyL 4,4 -benzophenone, etc.) other structural motifs employing platinum(II) have also been reported.2 0 The addition of bridging, multidentate N-donor ligands of various shapes and sizes to the labile complexes in a suitable solvent system has afforded several classes of discrete, plat-inum(II)-containing polygons, polyhedra, and catenanes. 

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