Propyne, 715 table

The carbon-carbon single-bond length also decreases along an analogous scries, ethane, propylene, propyne (Table 8.4). We notice that these diflcrences... 

Similar metalation studies were carried out on l,3-bis(trimethylsilyl)propyne. The IR bands observed in the 2200-1600 cm region of acetylenes, allenes and aU the Uthiated derivatives are summarized in Table 8. 

The authors noticed that polylithiated phenylallenes have a vibrational behaviour similar to that of polylithiated propynes and butynes (Table 8) . The monolithium compounds from terminal acetylenes were found to have acetylenic structures (2050 cm ), whereas the monolithium derivatives of non-terminal acetylenes could exist in either acetylenic (2000 cm ) or allenic (1870-1850 cm ) forms (Table 8) °. The polylithium... 

The reaction of 1-phenyl-l-propyne (IPP) was then studied after modilying the catalyst with trans-cinnamaldehyde (TCA), trans-cinnamonitrile (TCN), 3-phenylpropionitrile (3PPN), and 3-phenylpropylamine (3PPA). The first-order rate constant calculated for the loss of 1-phenyl-l-propyne in each of the systems is reported in Table 1. All the modifiers were unreactive under the conditions used. 

Table 1. First-order rate constants (min ) for the hydrogenation of 1-phenyl-l-propyne in the presence of modifiers.

The only significant loss of alkynes is reaction with OH, for which a pressure dependence is observed. Table 6.15 gives the high-pressure limiting rate constants for the OH reactions with acetylene, propyne, 1-butyne, and 2-butyne. The reaction of acetylene approaches the high-pressure limit at several thousand Torr (see Problem 5). However, for the larger alkynes, the reactions are essentially at the high-pressure limit at 1 atm (and room temperature). 

Rhodium-catalyzed silylformylation proceeds smoothly in branched 1-alkynes at 25 °C as shown in Table 3. The stereochemistry at the chiral carbon involved in alkynes is retained intact under the silylformylation conditions. (A)-28, (rhodium particles co-condensed with mesitylene. 3-Trimethylsilyl-l-propyne 40 reacts similarly to give 41 (Equation (7)). " / //-Butylacetylene does not work as a substrate for the silylformylation because of the bulky tert-huty group on the i/>-carbon. In contrast to /< r/-butylacetylene, trimethylsilylacetylene 42 gives 43 in a fair yield (Equation (8)). ... 

As seen in Tables II-IV, dialkylamines react with the substituted terminal acetylenes to give only trans-aminovinyl products. Primary aliphatic amines react with both ethyl propiolate and 1-ethylsulfonyl-l-propyne to give mixtures of cis and trans products and with p-tolylsulfonylacetylene to give only trans products. Ethylenimine reacts with ethyl propiolate and 1-ethylsulfonyl-l-propyne to give mixtures of cis and trans products. Aniline reacts with p-tolylsulfonylacetylene to give a mixture of cis and trans products. The solvent has a great effect on the cis- and trans ratio when ethylenimine is used. 

Large 2JCC couplings are observed if one or both of the coupling carbon atoms have a high character (hexynoic acid, propyne, cyclobutane ring carbons), or when the coupling path includes an electron deficient carbon atom such as a carbonyl function (Table 3.11(b)). 

The mechanism of the Au(III) catalysis proposed in Scheme 5 implies the stereoselective formation of the new C-C bond which, of course, cannot be observed in the final product when terminal alkynes are used (the aryl group and the former alkyne hydrogen are situated at the same side of the double bond in the vinyl-Au intermediate). For the reaction of 1-phenyl-l-propyne and mesitylene 1 (see below, Table 1) the proposed mechanism should lead to preferential formation of the Z isomer which is, in fact, observed [2]. The formation of a small amount of E isomers can be explained by isomerization of the initially formed Z compound. Such isomerization was, in fact, observed directly in the case of related electron-poor alkynes [4],... 

A sample of catalyst was placed in the environmental cell within the FTIR spectrometer, reduced as outlined in the Experimental section, and subjected to a 1 3 propyneidhihydrogen reaction mixture. The bands observed in the various spectra are reported in Table L At no time were any bands observed which indicated the presence of propane and the pressure fall was consistent with the conversion of propyne to propene. 

The pulse-flow reaction study performed at 298 K with a propyne dihydrogen ratio of 1 3, confirmed many of the infra-red spectroscopy results even though there was a considerable difference in residence time between the systems. No propane was detected in the reactor eluant and, apart from 10 % of the first pulse, only C-3 hydrocarbons were observed in the gas phase, supporting the infra-red results which indicated only C-3 species on the surface. It is also clear from Table 2 that the effect of the higher hydrogen concentration is to reduce the extent of carbon deposition over the first four pulses. The results at the lower temperature and dihydrogen propyne ratio, show that as the surface is covered with retained species the rate of hydrogenation decreases, the amount of carbon deposition decreases, and... 

The physical properties of alkynes (Table 9-2) are similar to those of alkanes and alkenes of similar molecular weights. Alkynes are relatively nonpolar and nearly insoluble in water. They are quite soluble in most organic solvents, including acetone, ether, methylene chloride, chloroform, and alcohols. Many alkynes have characteristic, mildly offensive odors. Ethyne, propyne, and the butynes are gases at room temperature, just... 

Addition of various hydrogen halides to propyne has been investigated by Griesbaum et al. (1965) (la-c of Table 2). The product distribution parallels that obtained from allene under identical conditions and the most likely mechanism involves formation of a propenyl cation which may react with halide ions to give the expected addition products or cyclodimerize to 1,3-dihalocyclobutane (see discussion in section II, Bib). 

The kinetics and stereochemistry of addition of HC1 to 1-phenyl-propyne and to 3-hexyne in acetic acid have been found to be different in the two cases (4 and 5 of Table 2) (Fahey and Lee, 1966,1967,1968). 

The product of interest is propylene and propane which are contaminated with propyne (methyl acetylene), allene and cyc/o-propane. A typical composition is given in Table 5.1. 

All of the syntheses shown in Table 19 were achieved by us for the first time. These polymers are all new polymers, though high-molecular-weight poly(terf-butylace-tylene) 9) and poly(l-phenyl- 1-propyne)55) were also prepared at similar periods with catalysts 3 and 7, respectively. 

The Pq2 and Po2/Pn2 values of substituted polyacetylenes so far determined are given in Table 30. Poly[l-(trimethylsilyl)-l-propyne] shows the highest P0z value... 

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