Hydrocarbon formulas for

The formula for cyclic hydrocarbons has been established from data on hydrocarbons whose molecular weights are lower than 140 and must not be used for higher molecular weights. 

An important property of aromatic hydrocarbons is that they are much more stable and less reactive than other unsaturated compounds Ben zene for example does not react with many of the reagents that react rapidly with alkenes When reaction does take place substitution rather than addition is observed The Kekule formulas for benzene seem mcon sistent with its low reactivity and with the fact that all of the C—C bonds m benzene are the same length (140 pm)... 

Although the term terpene once referred only to hydrocarbons current usage includes functionally substituted derivatives as well grouped together under the general term isoprenoids Figure 26 6 (page 1086) presents the structural formulas for a number of representative examples The isoprene units m some of these are relatively easy to identify The three isoprene units m the sesquiterpene farnesol, for example are mdi cated as follows m color They are joined m a head to tail fashion... 

Abbreviations for Ligand Names. Except for certain hydrocarbon radicals, for ligand (L) and metal (M), and a few with H, all abbreviations are in lowercase letters and do not involve hyphens. In formulas, the ligand abbreviation is set off with parentheses. Some common abbrevia-... 

Two-Dimensional Representation of Chemical Structures. The lUPAC standardization of organic nomenclature allows automatic translation of a chemical s name into its chemical stmcture, or, conversely, the naming of a compound based on its stmcture. The chemical formula for a compound can be translated into its stmcture once a set of semantic rules for representation are estabUshed (26). The semantic rules and their appHcation have been described (27,28). The inverse problem, generating correct names from chemical stmctures, has been addressed (28) and explored for the specific case of naming condensed benzenoid hydrocarbons (29,30). 

Discussion. The designers of this formula do not present a universal formula for all possible cases of pumping hydrocarbons. 

The ethers are a group of compounds with the general formula R-O-R . The R, of course, stands for any hydrocarbon backbone, and the R also stands for any hydrocarbon backbone, but the designation R is used to indicate that the second hydrocarbon backbone may be different from the first. In other words, both the hydrocarbon backbones in the formula may be the same, but the is used to indicate that it may also be different. R-O-R as the general formula for the ethers is also correct. The fact that there are two hydrocarbon backbones on either side of an oxygen atom means that there will be two hydrocarbon names used. 

Fig. 18-11. Structural formulas for some five-carbon saturated hydrocarbons.

Self-Test 18.4B Halogen atoms can substitute for hydrogen atoms in hydrocarbons. Write the condensed structural formulas for the four isomers with the molecular formula C4H9Br. 

The alkene series of hydrocarbons is characterized by having one double bond in the carbon chain. The characteristic formula for members of the series is C H2 . Since there must be at least two carbon atoms present to have a carbon-to-carbon double bond, the first member of this series is ethene, C2H4, also known as ethylene. Propene (propylene), C,Hh, and butene (butylene), C4HK, are the next two members of the series. Note that the systematic names of these compounds denote the number of carbon atoms in the chain with the name derived from that of the alkane having the same number of carbon atoms (Table 21-2). Note also that the characteristic ending -ene is part of the name of each of these compounds. 

Over the temperature interval 165 K to 300 K, the calculations of Silinsh and Jurgis (1985) indicate that the thermalization rate in pentacene decreases from 3 X 1012 to 0.8 X 1012 s 1. The trend is opposite to what would be expected in liquid hydrocarbons and may be attributed to the rapid increase of mcff with temperature. The calculated mean thermalization distance increases with incident photon energy fairly rapidly, from 3 nm at 2.3 eV to 10 nm at 2.9 eV, both at 204 K. With increasing temperature, (r) decreases somewhat. These thermalization distances have been found to be consistent with the experimental photogeneration quantum efficiency when Onsager s formula for the escape probability is used. 

Cycloalkanes are cyclic saturated hydrocarbons with the general formula C H2 . Therefore, a substance with the formula C3H8 could not be a cycloalkane, since C3H8 conforms to the general formula, C H2 +2, the molecular formula for an alkane. It is, however, too small to be a branched alkane with a methyl group attached to the longest chain. In fact, C3H8 is propane. 

Formulas for Kinetic Parameters of Hydrocarbon Autoxidation as Chain Reaction in Quasistationary Regime Chain Length v, Critical Concentration of Inhibitor [lnH]cr, and Quasistationary Concentration of Hydroperoxide [ROOH]s. The Following Symbols are Used / = k3/ka and V[0 is the Rate of Free Radical Generation on Reaction of RH with Dioxygen [33,38,45]... 

Formulas for Induction Period Tof Inhibited Oxidation of Hydrocarbons in Quasistationary Regime. Symbols are the Following r0 = f [lnH]0vi0-1, = k3/ka, vi0 is the Rate of Free... 

The unsaturated open-chain hydrocarbons include the alkene or olefin series, the diene series, and the alkyne series. The alkene series is made up of chain hydrocarbons in which a double bond exists between two carbon atoms. The general formula for the series is CnH2n, where n is the number of carbon atoms. As in the paraffin series, the lower members are gases, intermediate compounds are liquids, and the higher members of the series are solids. The alkene series compounds are more active chemically than the saturated compounds. They react easily with substances such as halogens by adding atoms at the double bonds. 

Each organic family follows a set pattern. You have just seen that you can represent the hydrocarbon part of a functional family by the letter R. All the structures below belong to the primary amine family. What is the functional group for this family Write the general formula for an amine. 

The general formula for an ester is RCOOR, where R is a hydrogen atom or a hydrocarbon, and R is a hydrocarbon. You can think of an ester as the product of a reaction between a carboxylic acid and an alcohol, as shown in Figure 1.26. 

The time-series analysis results of Merz et were expressed in first-order empirical formulas for the most part. Forecasting expressions were developed for total oxidant, carbon monoxide, nitric oxide, and hydrocarbon. Fitting correlation coefficients varied from 0.547 to 0.659. As might be expected, the best results were obtained for the primary pollutants carbon monoxide and nitric oxide, and the lowest correlation was for oxidant. This model relates one pollutant to another, but does not relate emission to air quality. For primary pollutants, the model expresses the concentrations as a function of time. 

One important application is to deduce the molecular weight and formula for a gas. Assume you know that the hydrocarbon propylene is, by weight, 85.6% carbon and 14.4% hydrogen. Then the atomic ratios of the com-pound are... 

The formulas for and B reflect the fact that these are hydrocarbons, while the formula for compound C includes the information that catalytic hydrogenation yields an increase of two mass units (corresponding to two hydrogen atoms). In addition, the hydrogenation reaction indicates that A and B are alkenes. 

Smittenberg, J., and Mulder, D. Relations Between Refraction, Density, and Structure of Series of Homologous Hydrocarbons. I. Empirical Formula for Refraction and Density at 20° of n-AIkenes and n-Alpha-Alkenes. Rec. Trav. Chim. 67 (1948) 813-25, 826-38. 

Silicon forms a series of hydrides known as silanes, formula SinH2n+2, where n is the number of silicon atoms in the molecule. This general formula for the silicon hydrides is similar to the CnH2n+2 for the alkane class of hydrocarbons. The names, synonyms, CAS Registry numbers, formulas, and molecular weights of the first four hydrides are given below ... 

Spectroscopic vibrational data of benzenoid hydrocarbons are scarce. Fortunately, it is now justifiable to take advantage of the regularities of the ZPE - - (Ht — Hq) energies observed during the buildup of alkyl chains, namely, the gain of 18.213 kcal/mol for each added CH2 group. Hence it appears safe to use the following formula for alkyl substitution, based on the experimental ZPE-f (//j-—//q) value (66.22 kcal/mol) deduced for benzene in the harmonic oscillator approximation [27,193]... 

To help develop a familiarity with Eq. (10.37), we examine a general formula for saturated hydrocarbons, C H2 +2-2m> containing n carbon atoms and m chair or boat six-membered cycles. These alkanes contain (n — 1 + m) CC bonds and (2n + 2 — 2m) CH bonds hence... 

Non-Steady State Equations with Correction for Spontaneous Initiation and First-Order Termination. Thoroughly purified hydrocarbons should exhibit a square-root dependence of oxidation rate on initiation rate, R we found, however, that even if this behavior is obtained with Ri of the order of 10 8 mole per liter per sec., deviations may occur with the low rates of initiation used in the non-steady state measurements (R 10 n). Also, spontaneous initiation of the order of R — 10 12 may occur. If we assume that the deviations can be described as a constant first-order termination, we can derive corrected formulas for the nonsteady state behavior upon adding a small amount of inhibitor AH or initiator AR, as follows. 

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