Hydrogen, substitution

For the synthesis of vinylic halides via halofunctionalization of alkynes, see page 655, Section 4. 

f-BuOjH or (r-BuO 2 CuCl2, cat PdCl2, H20 NCS, H20 cinhconh2, h2o ONHCONH2, HOAc, H20 TsNCINa, H20 

Ag20 I2, Ag02CCF3/Me0H I2, PDC, molecular sieves I(py)2BF4, H20 NIS, H20 

For intramolecular reactions, see page 889, Section 2. Review Russ Chem Rev 41 740 (1972) 

Br SR RSX(X = a, Br) The Chemistry of the Sulfenic Acids, G. Thieme, Stuttgart (1973), p 2 (review) Topics in Sulfur Chemistry, G. Thieme, Stuttgart (1977), Vol 3, p 100 (review) Chemistry of Double-Bonded Functional Groups, Suppl A, Part 2, Ed. S. Patai, Wiley, Chichester (1977), Chpt 9 (review) Acct Chem Res 12 282 (1979) (review) 

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Reaction with a Metal Fluoride. A second technique for hydrogen substitution is the reaction of a higher valence metal fluoride with a hydrocarbon to form a fluorocarbon ... 

Scheme 10 Reaction patterns of P-hydrogen substituted NHPs...

These types of catalysts, [Cp LnCH(SiMe3)2], are also used to hydrogenate substituted methylenecyclopentenes and cyclohexenes in good to very good dia-stereoselectivities, especially when the substituent is in the a-position to the al-kene (Tables 6.10 and 6.11). However, the presence of functional groups such as amine or ether is detrimental to catalysis. 

The ferrocene-oxazoline catalyst 19 (Fig. 29.7) has recently been used to hydrogenate substituted quinolines [18]. The ligand synthesis is again similar to that of the original PHOX ligand, with introduction of phosphorus via orthometallation. 

In contrast to saturated hydrocarbons, the unsaturated hydrocarbons react with atomic fluorine by two pathways, i.e. (atomic fluorine addition at >C=C< double bond and hydrogen substitution by fluorine atoms. The reaction of fluorine with aromatic hydrocarbons proceeds with the formation of F-derivatives and hydrogen atoms break off ... 

A second example (where the step sensitive to carbon isotope substitution precedes the one sensitive to hydrogen substitution) can be treated similarly. If we assume that the conversion of ES to El in scheme 11.49 (the step involving k3 and k4) is characterized by a carbon KIE, while the following step (El to EP) exhibits an hydrogen KIE, the equations corresponding to Equations 11.50 and 11.51 are ... 

Hydrogen substitution in CgHsF, CgHjCl, and CgHsBr by AtCl and AtBr is less efficient than the competing halogen-replacement reactions in these systems (vide supra) the total radiochemical yields are only a few percent and are poorly reproducible (43, 99,104). 

Formation of the phosphide 54 can be recognized by the orange color in the reaction solution when LiCMes is added. Addition of Me3CCl causes the subsequent hydrogen substitution for lithium in 54. As LiCl and isobutene are eliminated, the hydrogenated triphosphane 53 is formed [Eq. (9a)]. 

Deuteration of one end of the allyl moiety in these compounds removes the equivalence of the two positions and in place of the single line for the terminal position, two separate absorptions should appear (W). One, in the normal decoupled spectrum, is a singlet for the hydrogen substituted carbon, and the other a weak quintet for the deuterated end which would be difficult to observe. These two signals would bracket the normal singlet. If a mixture of deuterated and undeuterated allyl compound is used, therefore, two easily observable peaks should appear, one in the normal position, the other shifted. In the spectra of allyllithium and allylsodium the line from the deuterated compound appeared I and 11 Hz upfield respectively, at 0°C, of the normal lines. The potassium compound only showed a somewhat broadened line. At -80°C the separation for allyllithium was 22 Hz. 

Since all the C atoms of fullerenes are quarternary, and therefore contain no hydrogens, substitution reactions characteristic for planar aromatics are not possible... 

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