Methyl formate, from combustion

The detection of 1,2-propylene oxide in the products from methyl ethyl ketone combustion is particularly interesting. It parallels the formation of ethylene oxide in acetone combustion (8) and of 1,2-butylene oxide in the combustion of diethyl ketone. Thus, there is apparently a group of isomerization reactions in which carbon monoxide is ejected from the transition state with subsequent closing of the C—C bond. Examination of scale molecular models shows that reactions of this type are, at any rate, plausible geometrically. 

Thomsen 523 determined the heat of combustion of gaseous methyl iodide, from which can be deduced A/7 (CH3l g)25°c -4 9 kcal mole b (Small differences of two- or three-tenths of a kilocalorie in these values from those quoted elsewhere are due to the use here of the most modern subsidiary thermal data.) For some reason this result has not been looked on with much favour, and two recent thermochemical researches have been carried out a main result of which is essentially the determination of the heat of formation of methyl iodide, though it is expressed as the G -1 l >ond energy 3 3 5, 368 In two other recent researches, the heat of formation of methyl iodide has been in the one the main object, and in the other an important incidental result Moreover, direct... 

Some exceptions to the general rules occur. Cyclopentene is completely combusted, undoubtedly because of the high reactivity of cyclo-pentadiene. 4,4-Dimethyl-1-pentene is expected to produce an unsaturated aldehyde, but instead 2,3-dimethylpentadiene is the initial product. A methyl shift from a quarternary carbon is apparently easy, permitting formation of a diene instead of the oxygenated compound. 3,3-Dimethyl-l-butene is not expected to react at all under the general rules, but here also a methyl shift occurs so that diene, olefin aldehyde, diene aldehyde, and diene dialdehyde are formed. The reactivity of the latter olefin relative to 1-butene, measured by oxidation of a mixture at low conversion, was 0.21, while that of 4,4-dimethyl-1-pentene was 0.75. These reactivities suggest that isomerization occurs before reaction for 3,3-dimethyl-l-butene, while isomerization probably occurs after the aUyl intermediate is formed in the case of the pentene. 

Volatile by-products include methyl acetate, methyl formate, methanol, formic acid, methane, carbon oxides, and methyl bromide. The sources of carbons for the formation of volatiles result from overoxidation (i.e., combustion) of both HOAc and pX [18b, 67]. Partenheimer has written that the steady-state Co(III) concentration in the reaction is correlated with the level of overoxidations, resulting in these volatile by-products [8]. Very little research has been published on Co(III)-catalyzed overoxidation side reactions. We speculate that the reduction of Co(III) species can occur either via oxidation of or via oxidation... 

Because there are no directly measured enthalpy of formation data from combustion calorimetiy for the isomeric di-terf-butylated benzenes, we must take a slightly different approach to study their energetics. For any R, the enthalpy of reaction of the isodesmic, or transalkylation, reaction 18 is equivalent to the expression for D ), eq 17. If the m and jo ferf-butyl substituents behave similarly to methyl and ethyl substituents, then the desired enthalpy of formation for these di-ferf-butyl benzenes can be obtained experimentally from reactlon/equilibrium calorimetiy for reaction 18, R = ferf-butyl in the presence of a Lewis acid catalyst. 

Thus methyl radicals are consumed by other methyl radicals to form ethane, which must then be oxidized. The characteristics of the oxidation of ethane and the higher-order aliphatics are substantially different from those of methane (see Section HI). For this reason, methane should not be used to typify hydrocarbon oxidation processes in combustion experiments. Generally, a third body is not written for reaction (3.85) since the ethane molecule s numerous internal degrees of freedom can redistribute the energy created by the formation of the new bond. 

Our further analysis of the enthalpy of formation of 2-methylbicyclo[2.2.1]heptene only worsens the disparity. That is, we find methylation of one doubly bonded carbon in gaseous cyclopropene, cyclopentene and cyclohexene is accompanied by a decrease in enthalpy of formation of 34, 38 and 38 kJmol-1, i.e. 36 2 kJmol-1. The recommended enthalpy of formation of bicyclo[2.2.1]heptene (see Reference 60) is 90 kJmol-1 and so we would predict an enthalpy of formation of its gaseous 2-methyl derivative of 90 — 36 54 kJmol-1. Using our standard enthalpy of vapourization estimation protocol we would predict a phase-change enthalpy of 40 kJmol-1 for this species, and so derive an enthalpy of formation of liquid 2-methylbicyclo[2.2.1]heptene of ca 54-40 15 kJmol-1. That is, if anything, the exocyclic species is too stable if we compare this derived value with 4.5 1.8 kJmol-1 derived from the available combustion calorimetric data. 

The generally accepted 529 value of the heat of formation of carbon tetrachloride is due to Bodenstein et who measured the heat of the reaction GGI4 4- 2H2 G + 4HC1. They obtained A//y(CCl4 g) = 25 5 kcal, but in view of the slight uncertainty about the heat of formation of the form of carbon produced, the figure after the decimal point is probably not justified. From this (C C1) =70 0 kcal. The heat of formation of methyl chloride is due to a combustion by Thomsen 523 20 kcal. From... 

It should be noted that the heats of formation of CBr4, CH2Br2, and CHBr3 given by the N.B.S. are calculated . Methyl bromide has been burned by Thomsen 523 but in view of the difficulties attending the combustion of halogen-containing compounds we prefer to deduce E Ca Br) from ethyl bromide, the heat of formation of which has been obtained by equilibrium methods in... 

N-methylation is not expected to result in a nearly identical enthalpy of formation value to that of the C-methylated species. Why should it Indeed, from a consensus of combustion calorimetry measurements, the liquid18 21 enthalpy of formation for Af-methylaniline is 34 2 kJ mol-1 and for the gas19,21 is 84 2 kJ mol-1. Results from reaction calorimetry22 are compatible with these values. While methylation of the aromatic ring is quite exothermic, formal methylation of the aniline nitrogen is essentially thermoneutral. 

N.m.r. chemical shifts of a number of monoterpenoids of this class are included in a study of bicyclo[4,l,0]heptanes. A further paper in a series on enthalpies of combustion and formation concerns the 3,4-epoxycaranes. (+)-Car-2-ene and (—)-car-2-ene of high optical purity have been synthesized from the respective (-)- and (+)-rran5-caran-2-ones, via the analogous and uncited tosylhydrazone/methyl-lithium route used by Cocker et al. for synthesizing (—)-cw-car-4-ene (Vol. 1, p. 47), thus providing access (Vol. 2, p. 29, ref. 108) from the readily available (+)- and (-)-dihydrocarvones. Cocker et al. have synthesized norcaran-3-one via dibromocarbene addition to 4,4-dimethoxy-cyclohexene and treatment with lithium dimethylcuprate) from which car-2-ene, car-3-ene, and car-3(10)-ene were prepared. ... 

Deliquescent, orthorhombic, elongated, six-sided tablets from dimethyl phthalate. dj 1.282. mp 45-46. bp0J 83. Fomin of dicyandiamide begins at 122. Dipole moment in benzene at 2Cryoscopic constant (water) 26.8-28.4. Sp ht 0.547 cal/g/ C between 0° and 39. Heat of formation 14.05 kcal/mole (25 ) heat of combustion —176-4 kcal/-mole (25 ) heat of fusion 2.1 kcal/mole. Heat of vaporization 16.4 kcal/mole. Soly (g/100 g soln) in water at 15 77.5, at 43 100 in butanol at 20 28.8, in methyl ethyl ketone 50.5, in ethyl acetate 42.4. Sol in alcohols, phenols, amines, ethers, ketones. Very sparingly sol in benzene, haJogeaated hydrocarbons. Practically insol in cyclohexane. Solid cyanamide should be stored in a cool, dry place. Polymerizes at 122. Optimum pH for storage of solns is 4, Attacks various metals. Solns can be stored in grass provided they are stabilized with phosphoric, acetic, sulfuric, or boric acid. LDM in rats 125 mg /kg orally. 

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