Bonding phenyl

An intriguing reaction has been reported that does not exactly fit into the category of Michaelis-Arbuzov reaction but does involve nucleophilic attack of a neutral trivalent phosphorus for generation of a new C-P bond. Phenyl- and methyldichlorophosphine have been reported to attack the strained cyclopropane ring system of 1,3-dehy-droadamantane, overall adding P-Cl across the most strained bond of the ring system (Equation 3.5).140... 

The nomenclature of the RP is not consequent. The RP most often used contains octyl (RP C8) or octadecyl (RP C18) groups. There is no differentiation even when two methyl groups are introduced additionally with the silane (as with monofunctional silanes) or only one (difunctional) or none (trifunctional silane). Some manufacturer use silanes with bulky side groups (e.g., isopropyl groups) to improve the hydrolytic stability of the bonded phases, but here also, only the longest alkyl group is used in nomenclature. RP C8 and RP C18 are the work horses in HPLC. Shorter chains (RP4) are used in protein separations, and special selectivity can be obtained with bonded phenyl, cyano, amino or fluoro groups. 

The structures of methyhnagnesium tris(3-ferr-butylpyrazolyl)phenylborate (230) and ethyknagnesium tris(3-terr-butylpyrazolyl)phenylborate (231) have been determined by X-ray crystallography and are shown schematically (Figure 94) . Their structures show large similarities with that of 227 and 228 and only differ in the presence of a boron-bonded phenyl group in 230 and 231. 

Figure 5.28 Dimerof[NBu3Me][Au(PPh2CH2SnBnHn)2] formed via B-H- -Au bonds. Phenyl substituents and part of the boron cluster cages have been omitted for clarity.

Ionic initiators are much more specific toward the type of monomer and can initiate polymerization in some cases where radical initiation is ineffective (cyclic, vinyl ether, or allylic monomers). Monomers suitable for anionic initiation are those with an electron-withdrawing substituent attached to the double bond (phenyl, carbonyl, etc.). The reaction consists... 

Are the primary differences in polarity Partition columns are available that vary in polarity from nonpolar (octyldecyl), through intermediate polarity (octyl and cyanopropyl), to polar (silica). Some columns have similar polarities, but differ in their specificity. Qg and the phenyl column have similar polarities, but Ci8 separates on carbon chain length, while phenyl separates fatty acids on both carbon number and number of double bonds. Phenyl columns also resolve aromatic compounds from aliphatic compounds of similar carbon number. In another example of similar polarities, C8 is a carbon number separator while cyanopropyl selects for functional groups. 

Pregosin and co-workers have shown that a detailed analysis of the trends in coupling and chemical shifts can be a valuable asset in determining the symmetry of a variety of Pd(2 +) and Pt(2 +) complexes. For example, in complexes of the type PdCl2La Ca in the ligand usually lies to lower field in the cis complex than in the trans complex while the para resonance in a phosphorus bonded phenyl ring is found at lower field in the trans complex than in the cis (80, 84). 

No formation of an ether substitution product is observed when the para-anilino position is substituted, e.g. when N-benzyl-p-toluidine is dehydrogenated with TPPO-. Substitution of the CH2-bonded phenyl ring does not occur 190). 

Another aspect of stability of the unsaturated systems concerns the n-bond strength of the double bonded fourth group elements, the experimental determination of which certainly represents problems. Nevertheless, from n-bond migration processes some insights may be derived about the relative stability of these n-bonds as a function of the double bond substituents. In this connection, I turn first to the question Are SiC-n-bonds stabilized by mesomeric effects of silicon bonded phenyl groups ... 

Mercury salts have previously been shown to be capable of cleaving cyclopropyl bonds. Phenyl-substituted cyclopropanes react with mercury(II) acetate to give 3-mercurio-l-methoxy-l-phenylpropane derivatives, which can undergo further reactions such as reduction with sodium borohydride or addition to alkenes. For example, treatment of phenyl-cyclopropane (1) with mercury(II) acetate in methanol, followed by the addition of sodium chloride, produced 3-(chloromercurio)-l-methoxy-l-phenylpropane(2) in good yield.When the primary mercury adduct was reacted with alkenes without isolation, the yields were lower than those in the two-step transformation. ... 

According to recent time-resolved triplet energy transfer experiments [224,225] with c/s-stilbene and 1,2-diphenylnorbornene (a model compound with inhibited double bond twisting), both compounds exhibit virtually the same nonvertical triplet excitation and relaxation behavior the respective relaxation energies are 63 and 42kJmol 1 [224], Single-bond (phenyl-... 

Benzene ring bonds phenyl-alkyl bond... 

The isomorphous series (b) that has members that differ only in the nature of the anion (BFJ or CIOJ) would be reasonably expected. However, the occurence of the o-bonded phenyl complex in this series is unexpected. All remaining members of the series in the monoclinic systems do not appear unusual or unexpected in any sense. 

Not just multi-component crystal structures but even simple molecular crystals can be quite difficult to classify using a simple predictive ranking of hydrogen bonds. Phenyl... 

Metalation of (94a) by Hg(OAc)2 in the presence of LiCl affords complex (95) in which the mercury atom is connected to o-carbon atom of the iV-bonded phenyl group. The reaction of Pd(OAc)2 with (94a-b) gives metalation at one of the P-bonded phenyl groups together with coordination at nitrogen, resulting in five-membered PdCN rings with a dimeric structure (96a-b). The dimer reacts with tetramethylethylenediamine (tmeda) to form a monomeric cationic complex (97a-b). ... 

Or /jo-palladation at the P-bonded phenyl group can also be achieved by treatment of the o-iodo derivative (98) with a mixture of Pd(dba)2 (dba = dibenzylidene acetone) and tmeda. The resulting neutral complex (99) reacts with T1(0S02CF3) and PhsP to yield a cationic complex (100). An insertion reaction of (99) with Me02CC=CC02Me results in a six-membered PdC4N chelate ring (101). ... 

Stationary phases with chemically bonded branched hydrocarbons, perfluoroalkanes, polyethylene glycol, cholesterol, or alkylaryl groups show different separation selectivities which can be useful for specific separations. For example, chemically bonded phenyl groups show preferential retention of aromatic compounds and increased shape selectivity for planar and rigid rod-like molecules. 

Reaction with Organolithium Reagents. The fluorination of vinyl lithium derivatives with NFSi has been demonstrated in good yields with complete retention of configuration about the double bond. Phenyl lithium reacts rather poorly with 7V-fluorobenzenesulfonlmlde, but more complex phenyl lithium derivatives have been fluorinated to prepare fluoro- and polyfluoro-veratraldehydes as well as complex fluorinated polyaromatic compounds. Organolithium derivatives of heterocycles have been fluorinated by reaction with NFSi at low temperature. In this manner, fluoro-pyrroles and 2-fluoro-5-methylthleno[3,2-b]pyrldlne are prepared from their corresponding llthlo-parent compounds (eq 16). ... 

---