Tert-Butyl acetylene

The kind of surface site catalyzing alkyne half-hydrogenation has been the subject of some speculation. Two possibilities are shown in Fig. 2.2. Certainly such a site should fit the evidence Burwell and associates obtained from the hydrogenation of di-tert-butyl acetylene (2,2,5,5-tetramethyl-3-hexyne). 31 They proposed that the molecule dislocated a surface atom, pulling it up out of the plane of the surface (Fig. 2.3). That work concluded that hydrogenation... 

The reactivity of OsHCl(CO)(P Pr3)2 toward alkynes depends on the type of alkyne used. Whereas phenylacetylene, propyne, and acetylene react by insertion to give the five-coordinate alkenyl derivatives Os ( >CI I=CHR Cl(CO)(PIPr3)2 (R = Ph, Me, H),31,33 the reaction with methylpropiolate affords a mixture of Os C(=CH2)C(OMe)0 Cl(CO)(P,Pr3)2 and 0s ( )-CH=CHC02Me Cl(C0) (P Pr3)234 (Scheme 3), and tert-butyl acetylene and diphenylacetylene are inert. 

Reaction of 1 with tert.-butyl-acetylene in presence of 0.36 mol-% of polystyrene-supported Pd(PPh3)4-catalyst gave terbinafine-base 5 with 90 % yield and excellent stereoselectivity. However, the mmover-rate of the re-used catalyst dropped dramatically in the second and third mn. A prolonged reaction time is necessary for complete conversion (table 1). 

Blobaum AL, Kent UM, Alworth WL, Hollenberg PF. Mechanism-based inactivation of cytochrome P450 2E1 and 2E1 T303A by tert-butyl acetylenes characterization of reactive intermediate adducts to the heme and apoprotein. Chem Res Toxicol 2002 15 1561-1571. 

Although less studied, the hydrocyanation of alkynes in the presence of soluble transition metal complexes has also been reported. - The reactions conducted with nickel(O) catalysts occur with cis stereochemistry, high regioselectivity, and moderate-to-high yields. Again, both steric and electronic effects control the regioselectivity. These points are illustrated by the data in Equation 16.11. Terminal, straight-chain alkynes such as l-hex)me react to form predominantly the branched nitrile, whereas tert-butyl acetylene reacts to form mostly the terminal nitrile. Reactions conducted with DCN have shown that the addition occurs in a syn fashion. ... 

The molecular weights obtained are very high with extremely broad molecular weight distributions. Poly(tert-butyl-acetylene) (P21) and poly(methyl-trimethylsilyl-acetylene) (P22) are white amorphous polymers, which can easily be solution cast into tough, completely colorless, transparent films. Therefore, the synthetic procedure was... 

Blobaum AL, Harris DL, Hollenberg PF (2005) P450 active site architecture and reversibility the inactivation of cytochromes P450 2B4 and 2B4 T302Aby tert-butyl acetylenes. Biochemistry 44 3831 3844... 

Azete 6 crystallizes as reddish needles of mp 37°C. In its chemical properties, 6 shows analogies to cyclobutadienes. Its flash pyrolysis at 700°C gives di-tert-butyl acetylene and tBu-CN AG for this decomposition is very high, since a concerted (2 + 2)-cycloreversion is not allowed according to the Woodward-Hoffman rules ... 

Di-tert-butyl-l,2-dithiete was obtained by heating 2,2,5,5-tetramethylhex-3-yne (di-tert-butyl acetylene) with sulfur in benzene in an autoclave at 190 °C [24]. It is thermally stable and exists in the dithiete form. Valence isomerization into the dithione form would enhance the steric strain in the molecule. 

In this paper, physical aging of gas permeability properties of PTMSP is described using the dud mode sorption and transport model, lliis model is also used to rationalize the increase in stability of gas permeation properties as a result of blending PTMSP with poly(tert-butyl acetylene) (PTBA). 

Poly(phenylacetylene), poly(butylacetylene), poly(tert-butyl acetylene), poly(4- H Polymerization mechanism 15... 

Instances in which cyclobutadiene complexes are the major products from the reactions of acetylene complexes with additional alkyne are uncommon. These generally have been found to be significant products with sterically hindered alkynes and with palladium and platinum metals. For example, phenyl tert-butyl acetylene was converted to the corresponding cyclobutadiene complex (one isomer) upon treatment with (PhCN)2 PdCl2 (Hos-okawa and Moritani, 1969) [Eq. (71)]. With sterically less demanding tolane,... 

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