Monomeric compounds

Uses. Furfural is primarily a chemical feedstock for a number of monomeric compounds and resins. One route produces furan by decarbonylation. Tetrahydrofuran is derived from furan by hydrogenation. Polytetramethylene ether glycol [25190-06-1] is manufactured from tetrahydrofuran by a ring opening polymeri2ation reaction. Another route (hydrogenation) produces furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, and 2-methyltetrahydrofuran. A variety of proprietary synthetic resins are manufactured from furfural and/or furfuryl alcohol. Other... 

Much effort has been invested into the search for monomeric compounds [86-90]. One of the few reliable indications for a base-stabilized monomeric complex involved the use of spectroscopic methods. The complexes 1 and 2 could be isolated and characterized below —20 °C with spectroscopic methods [91],... 

The heterocycles can be cleaved by reaction with 4-(dimethylamino)pyri-dine, yielding Lewis base-stabilized monomeric compounds of the type dmap—M(R2)E(Tms)2 (M = Al, Ga E = P, As, Sb, Bi). This general reaction now offers the possibility to synthesize electronically rather than kinetically stabilized monomeric group 13/15 compounds. These can be used for further complexation reactions with transition metal complexes, leading to bimetallic complexes of the type dmap—M(Me2)E(Tms)2—M (CO) (M = Al, Ga E = P, As, Sb M = Ni, Gr, Ee). 

CHEMICAL REACTIVITY IN HOMOLOGOUS SERIES OF MONOMERIC COMPOUNDS... 

Ziegler-Natta catalyst for polymerization of alkenes. Considerable attention has been directed to double-bonded Fischer carbenes of Cr and W, the Schrock carbenes of Ta and Ti, and cyclic polyene ligands of Fe, Co, Cr, and U. Carbonyls of transition metals from groups 6 to 10 of the periodic table include both the monomeric compounds such as Cr(CO)g, Fe(CO)5, Ni(CO)4 and those with two metal groups such as Mn2(CO)io and Co2(CO)s, which is used industrially for hydroformylation. Although their source has not been identified, it has been shown that volatile compounds from landfills contain carbonyls of Mo and W (Feldmann and Cullen 1997). 

This heterogeneous group contains eight monomeric compounds (124-131) not falling in any of the 13 preceding groups Some of them, however, are apparent precursors for compounds mentioned earlier [e.g., chalcostrobamine (131) for strobamine (122)]. 

The monomeric compound bis(phenyltellurido)(TMEDA) zinc has been synthesized with, once again, a particular interest in the controlled deposition of a pure solid state compound, in this case ZnTe nanocrystals.3 y... 

Imido chalcogen halides of the type RNEC12 (E=S, Se, Te) provide an interesting illustration of the reluctance of the heavier chalcogens to form -N=E< double bonds. The sulfur derivatives RNSX2 (X=F, Cl) are stable, monomeric compounds. 

Monomeric compounds (x = 1) containing M=E double bonds remained unknown until Power and Roesky et al. reported in 2001 on the synthesis of the first monomeric iminoalane and -gallane by oxidative addition of an organoazide to a sterically encumbered low-valent A1(I) compound 4 This reaction type has been shown previously to yield heterocyclic compounds by use of sterically less hindered [Cp Al]4.145 Very recently, von Hanisch and Hampe synthesized the first GaAs compound featuring a Ga=As double bond5 (Scheme 19, Figs. 41 and 42). 

The coordination of the phosphine P(ft-Pr)2Ph to the Lewis acidic Ga center is essential for the synthesis of both compounds. In the absence of any Lewis base, the most likely reaction product would be the heterocubane [ClGaSbSi(/-Pr)3]4. However, in analogy to the results observed for reactions of heterocycles [R MER with Lewis bases, leading to base-stabilized monomeric compounds, both the formation of 84 and 85 can be explained by reaction of such a heterocubane intermediate with the phosphine base. According to the description of heterocycles as head-to-tail adducts, heterocubanes may be described as Lewis acid-base adducts between two four-membered rings as shown in Fig. 45. 

The electrochemical reduction of azulene with carbon, platinum, lead or zinc cathode does not give any product, whereas that with magnesium electrode yields a dimeric compound as the only reduction product, though the dimeric compound is easily transformed to the corresponding monomeric compound by a mild oxidation as shown in equation 2825. 

Investigation of Low Molecular Weight Diluents. An investigation of low molecular weight monomeric compounds as diluents was carried out by blending either diethyl... 

R = Me, Bu. Compounds of the series with 244 X = / -Me, j9-NH2, / -Br are monomeric. Compounds of the series with X groups in orffro-positions show dimeric structure and have heptacoordinated Sn atoms. The great variation of bond strength in these compounds can be appreciated from the bond lengths in the dimeric case with R = Bu and X = 0-Cl ... 

This Li-phenyl interaction is similar to the r/ -Ph contact observed in the silicon-stabilized carbanion complex [Li C(SiMe2Ph)3 (THF)] (140). Addition of tmeda to 49 yields the monomeric compound [Li C(SiMe2Ph)(PMe2)2 (tmeda)l in which the lithium is bound by the two P atoms of the phosphinomethanide ligand and the two N atoms of the tmeda in a distorted tetrahedral geometry (139). There... 

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