Adduct compounds

While unsubstituted imidazo[l,5- ]pyridine when treated with MTAD and PTAD gives unstable 1 2 adducts, compounds 386 under the same conditions provide good yields of 387 (Equation 54) <1995JHC1525>. 

The extraction of a solute A may be improved by its reaction with another solute ( extraction reagent , or extractant), B, forming an adduct compound, AB. This occurs through chemical interaction between A and B. 

DISPROPORTIONATING SALTS A number of salts of weak acids and bases, such as boron trifluoride adduct compounds, dis-... 

Many adduct compounds of thorium chelates were prepared and the composition and melting points of some of them117,213 are included in Table 24. Attempts were made213, ... 

Simple fractional distillation processes for purification of metalorganics can be employed to remove some of these impurities, but this is a very inefficient approach. A dramatic improvement in the yield of many high-purity metal alkyl compounds resulted from the development of the adduct-purification scheme for the purification of metal alkyls, which was commercially developed by A. C. Jones and coworkers. This process uses the strong tendency of many metal alkyls to form stable adduct compounds with other reactants, thus making a difficult problem that is encountered in the epitaxial growth arena into an useful advantage in the synthetic arena. Actual synthetic and purification routes employed in the manufacture of metal alkyls are proprietary. It is a challenge to develop an optimized synthetic process that has the required purity, efficiency, volume, reproducibility, and yield. 

Neodymium-alcoholates were mentioned in the patent literature prior to Nd-carboxylates [37,38,224-228]. The Nd-alcoholates most frequently mentioned in literature comprise Nd(OBu)3 [224,225,229,230], Nd(0 Pr)3 [231-233], and Nd aryl oxides [185,234,235] (Scheme 3). Also adduct compounds... 

Malatesta et al.36 disclosed that spirooxazines react easily in their open merocyanine (MC) forms with free radicals to give deeply colored, reduced, free-radical adducts (FRA) that are devoid of photochromic activity. The radicals attack the C5I=C6 double bond of MC and yield stable, deeply colored, free-radical adducts (compound 29) that can no longer close back to the corresponding spiro form. The adducts absorb in the 510-560-nm region and are characterized by high molar absorptivities. 

The low concentration of the adduct compound is probably due to a slow addition of the methyl iodide and a rapid rearrangement of the adduct to form the acetyl. This is reasonable in view of the first order rate found for methyl iodide. 

This family of adduct compounds is extensive and some examples are given in Table 4.18. 

When the frilly reduced enzyme is allowed to react with O2, a more complicated sequence of events ensues (Figure 4), since now electrons are available also in the heme a and Cua centers. After formation of the O2 adduct (compound A), the next step is a ca. 30- j,s event which involves electron transfer from the low spin heme to the binuclear site. As reported by Morgan et al., the optical spectrum of the state formed is indistingishable from that of Pm if the absorption change owing to oxidation of heme a is accounted for. In contrast, Einarsdottir et al. have claimed that the spectrum of this Pr state formed from the fully reduced enzyme is different from that of Pm, and that Pr does not represent a stracturally... 

The treatment of neutral In(SePh)3 with [PPh4]Br also results in a selenolate adduct compound [PPh4][BrIn(SePh)3]. A copper-indium complex with bridging selenolates (Ph3P)2Cu[In(/i-SeEt)2(SeEt)2] was also reported. The action of selenium on [HB(3,5-(t-Bu)2Pz)3]In or [(t-Bu3Si)2ln]2 affords [HB(3,5-(t-Bu)2Pz)3]InSe or (t-Bu3SiIn)4Sc4 (45), respectively. The tellurium does not react with [HB(3,5-(t-Bu)2Pz)3]In. ... 

AI-Fluorosulfonylsulfimide reacts with benzonitrile to give 1 2 adducts compound 137 was isolated (Scheme 61) (78AG(E)129). 

Masento MS. Hewer A, Grover PL, et al. 1989. Enzyme-mediated phosphorylation of polycyclic hydrocarbon metabolites Detection of non-adduct compounds in the phosphorus-32 post-labelling assay. Carcinogenesis 10(8) 1557-1559. 

Radiation induced copolymerization of hexafluoroacetone xcith a-olefins has been done over a broad temperature range. From these experiments, it was confirmed that ethylene can be copolymerized below its critical temperature to give an alternating copolymer. A radical mechanism is involved at relatively high temperatures below —10°C, the mechanism has been confirmed to be ionic and may be cationic. Propylene can be copolymerized in a way similar to that of ethylene however, the rate of copolymerization was much slower. Isobutylene did not copolymerize with hexafluoroacetone at 0°C. A 1 2 adduct compound was obtained as the main product. At low temperatures, copolymerization proceeds to some extent. 

The significance of the Lewis concept is that it is much more general than other definitions. Lewis acid-base reactions include many reactions that do not involve Brpnsted acids. Consider, for example, the reaction between boron trifluoride (BF3) and ammonia to form an adduct compound (Figure 15.11) ... 

The biologically active monosaccharide 3-deoxy-D-ura6//io-heptulosonic acid 7-phosphate (8 DAMP) is an important intermediate in the biosynthesis of aromatic amino acids in plants (the shikimate pathway). As shown in Scheme 2, this compound has been produced in a combined chemical and enzymatic synthesis from racemic V-acetylaspartate 3-semialdehyde (4) and DHAP (1). The four-step synthesis proceeds in an overall yield of 13% (37% for the aldolase reaction). The enzymatic step generates the required, enantiomerically pure, syn aldol adduct compound (5). In view of the broad range of substrates tolerated by FDP aldolase, this method may be applicable to the production of analogs of DAMP. 

It was realized early that the morphine-related alkaloid thebaine, because of the conjugated diene in ring C, was the most chemically reactive of the opium alkaloids. A large variety of dienophiles readily underwent a Diels-Alder reaction with thebaine, affording several adduct compounds with opioid properties, including analgesia. 

A gallane-quinuclidine adduct (compound 19) has been used as an alternative Ga source for the MOMBE growth of GaAs films. The surface decomposition of compound 19 is similar to the related alane adduct, [AlH3 NMe3 ] 7, and growth of GaAs is observed at much lower temperatures than those employed when Ga alkyl precursors are utilized. 

Unstable benzene oxides (78JOC2711) and sulfides (74AG818) have also been identified as the corresponding PTAD adducts. Compound 178, an example of the former derivatives, is formed by dehydrohalogenation of 177 with sodium methoxide. Similarly, thermally unstable bis-episulfide 181 is formed from ditosylate 180. When either 178 or 181 was treated with PTAD, the corresponding adducts 179 and 182 were obtained in reasonable yields. 

The first solvent to be adopted at Hanford was methylisobutylketone ("MIBK" or "Hexone"). This solvent forms adduct compounds with coordinatively unsaturated compounds like the actinide nitrates, e.g. Pu(N03)4 2, where S repres ts tihe adduct molecule... 

The corresponding adduct compounds for 3- and 6-valent actinides are An(N03)3S3 and An02(N03)2S2. These chemically saturated neutral conqx>unds are soluble to differmt extent in organic solvents like kerosene, and — in the case of hexone — by hexone itself. The process using hexone is referred to as the Redox process. 

In the United Kingdom, 8, (J -dibutoxydiethylether ("dibutyl carbitol" or "Butex") was selected as organic solvent it forms the same kind of adduct compounds as hexone. Though more expensive, it was more stable, less flammable and gave better separations. 

Fe and Cu are bridged forms even transiently. Indeed, O2 binding to the 2e reduced heme/Cu site yields a ferriheme-superoxide/Cug adduct (compound A, Figure 1.7) with little or no interaction between bound O2 and Cug despite the suitable Fe-Cu distance ( 5 A) and Cu / potential. 

---