Portal de Periódicos da CAPES

Heats of combustion and isomerization of six pentadienes and spiropentane

1955; US government; Volume: 54; Issue: 3 Linguagem: Inglês

10.6028/jres.054.017

2376-5305

Frances M. Fraser, E.J. Prosen,

Catalysis and Oxidation Reactions

The heats of combustion of six pentadienes and spiropentane were measured by combustion of t he hydrocarbon vapors, carried by helium gas, in a fl ame at co nstant pressure ; the reaction was carried out in a glass reaction vessel contained in a calorimeter.The calorimeter system was calibrated by means of electri c energy.The experimental data y ielded the following values for the standa rd heat of combustion , -t;Fic O, at 25 ° C and co nstant pressure, of the gaseous hydrocarbon in gaseous oxygen to fo rm gaseous carbon dioxide and liquid water, with a ll the reactants and products in t heir t hermodynam ic stand ard reference states, in kilocalories per mole, where 1 k cal= 4. 1840 kj: 1,2-pentadiene, 777.14 ± 0.15 ; l ,cis-3-pentadiene, 763.30 ± 0.21 ; 1,trans-3-pen tad iene, 761.64 ± 0.15 ; 1,4-pentadiene, 768.94 ± 0.30 ; 2,3-pentadiene, 775.32 ± 0.16 ; 2-methyl-1,3butadiene (isoprene), 761.62 ± 0.23 ; spiropentane, 787.77 ± 0.17.From t he above data t he heats of isomerization to isoprene in kilocalories per mole were calculated to be 2-m ethyl-1 ,3-bu tadiene (isoprene) = 0 ; 1,2-pentadiene= -15.52 ± 0.23 ; l ,cis-3-pentadiene=-1.68 ± 0.27 ; 1,trans-3-pentadiene=-0.02 ± 0.22 ; 1,4-pentadiene = -7.32 ± 0.34 ; 2,3-pentael iene =-13.70 ± 0.23; spiropentane =-26.14 ± 0.24.Values of the heats of formation and hydrogenation were also derived from these elata.