Alkanes constitutional

Hydrogen bonding m carboxylic acids raises their melting points and boiling points above those of comparably constituted alkanes alcohols aldehydes and ketones... 

Open-chain aliphatic hydrocarbons constitute alkanes, alkenes, alkynes, and their isomers. Alkanes have the general formula C H2 +2, where n is the number of carbon atoms in the molecnles, snch as methane, propane, n-pentane, and isooctane. Alkenes or olefins are nnsaturated compounds, characterized by one or more double bonds between the carbon atoms. Their general formula is C H2 . Examples are ethylene, 1-butene, and... 

Over the past decade it has been established that for various substituents the i C chemical shift increment is a constitutive property. This applies to many systems e.g. benzenes, alkanes and alkenes. The availability of over 200 allenes, randomly substituted with groups of different nature, enabled us to prove that in the case of allenes the chemical shift increment is a constitutive property too, thus establishing a convenient method for estimating i ( C) values for allenes. 

Methane is the only alkane of molecular formula CH4 ethane the only one that is C2H6 and propane the only one that is C3Hj Beginning with C4H10 however constitutional isomers (Section 1 8) are possible two alkanes have this particular molecular formula In one called n butane, four carbons are joined m a continuous chain The nmn butane stands for normal and means that the carbon chain is unbranched The second isomer has a branched carbon chain and is called isobutane... 

The Number of Constitutionally Isomeric Alkanes of Particular Molecular Formulas... 

Table 2 3 lists the heats of combustion of several alkanes Unbranched alkanes have slightly higher heats of combustion than their 2 methyl branched isomers but the most important factor is the number of carbons The unbranched alkanes and the 2 methyl branched alkanes constitute two separate homologous senes (see Section 2 9) m which there is a regular increase of about 653 kJ/mol (156 kcal/mol) m the heat of combustion for each additional CH2 group... 

Two constitutionally isomeric alkanes have the molecular formula C4H10 One has an unbranched chain (CH3CH2CH2CH3) and is called n butane, the other has a branched chain [(CH3)3CH] and is called isobutane Both n butane and isobutane are common names... 

As shown m Figure 16 1 however the presence of an oxygen atom permits ethers to participate m hydrogen bonds to water molecules These attractive forces cause ethers to dissolve m water to approximately the same extent as comparably constituted alco hols Alkanes cannot engage m hydrogen bonding to water... 

We have often seen that the polar nature of a substance can affect physical properties such as boiling point This is true for amines which are more polar than alkanes but less polar than alcohols For similarly constituted compounds alkylamines have boiling points higher than those of alkanes but lower than those of alcohols... 

The nitro alcohols can be reduced to the corresponding alkan olamines (qv). Commercially, reduction is accompHshed by hydrogenation of the nitro alcohol in methanol in the presence of Raney nickel. Convenient operating conditions are 30°C and 6900 kPa (1000 psi). Production of alkan olamines constitutes the largest single use of nitro alcohols. 

Reactions of alkanedicarboxylic acids with sulfur tetrafluoride afford, in general, mixtures of bis(trifluorQmethyI)allcanes, cyclic 0(,a,a, a -tetrafluoro ethers, linear bis(pentafluoroalkyl) ethers, and polyfluoroethers The cyclic ethers constitute the major products of the reactions with alkane-1,2 dicarboxyhc acids, they are also formed in the reactions with alkane-1,3-dicarboxylic acids but not with 1,1- nor 1,4-dicarboxylic acids [211] (equation 105)... 

Compounds like the two C4M [() molecules and the three C3I I 12 molecules, which have the same formula but different structures, are called isomers, from the Greek isos + meros, meaning "made of the same parts." Isomers are compounds that have the same numbers and kinds of atoms but differ in the way the atoms are arranged. Compounds like butane and isobutane, whose atoms are connected differently, are called constitutional isomers. We ll see shortly that other kinds of isomers are also possible, even among compounds whose atoms are connected in the same order. As Table 3.2 shows, the number of possible alkane isomers increases dramatically as the number of carbon atoms increases. 

Constitutional isomerism is not limited to alkanes—it occurs widely throughout organic chemistry. Constitutional isomers may have different carbon skeletons (as in isobutane and butane), different functional groups (as in ethanol and dimethyl ether), or different locations of a functional group along the chain (as in isopropylamine and propylamine). Regardless of the reason for the isomerism, constitutional isomers are always different compounds with different properties, but with the same formula. 

Alkanes are a class of saturated hydrocarbons with the general formula C H2n. -2- They contain no functional groups, are relatively inert, and can be either straight-chain (normal) or branched. Alkanes are named by a series of IUPAC rules of nomenclature. Compounds that have the same chemical formula but different structures are called isomers. More specifically, compounds such as butane and isobutane, which differ in their connections between atoms, are called constitutional isomers. 

Notice the trend. Let s ignore the two extremes above (alkane and carbon dioxide), and let s focus on the middle three compounds alcohols, aldehydes, and carboxylic acids. Carboxylic acids are at a higher oxidation state than aldehydes, which in turn, are at a higher oxidation state than alcohols. Now imagine that we are running a reaction that converts an alcohol into an aldehyde or a carboxylic acid. This reaction would constitute an increase in oxidation state. Whenever we run a reaction that increases the oxidation state, we say that an oxidation has occurred. Therefore, converting a primary alcohol into an aldehyde or a carboxylic acid is called an oxidation ... 

The dsz genes in ECRD-1 are expressed at a baseline level constitutively in the presence of sulfate, although their levels are presumably higher in the absence of sulfate. Studies were conducted with and without sulfate. The Rhodococcus cells are known to use alkanes as substrates, thus an alternate carbon source was used to minimize hydrocarbon degradation. The hydrocarbon profile of the oils was demonstrated to be the same before and after the desulfurization. The experiments were aimed at identifying the extent of desulfurization of these oils and so were conducted at oil to water ratio of 1 1000. The results showed 90% or higher removal of CO to C4 DBTs in fully induced cells (without sulfate). In the presence of sulfate, the extent removal was lower. 

In this chapter, we will study the elementary reaction steps of these mechanisms focusing primarily on the anthraphos systems. This chapter begins with a description of the impact of different methods (coupled cluster, configuration interaction and various DFT functionals), different basis sets, and phosphine substituents on the oxidative addition of methane to a related Ir system, [CpIr(III)(PH3)Me]+. Then, it compares the elementary reaction steps, including the effect of reaction conditions such as temperature, hydrogen pressure, alkane and alkene concentration, phosphine substituents and alternative metals (Rh). Finally, it considers how these elementary steps constitute the reaction mechanisms. Additional computational details are provided at the end of the chapter. 

This procedure constitutes the first example of one-step conversion of a /-alkane to the corresponding /-alkyfamine. Other hydrocarbons in this class, such as isobutane, have also been aminated with good results.7 Only a very limited number of convenient routes, e.g., the Ritter reaction, are available for the preparation of /-carbinamines. The present preparation illustrates a simple method that utilizes a novel substrate. 

The catalytic systems described here are liquid triphasic ones, with a heterogeneous catalyst such as supported noble metals (Pt, Pd), or high-surface-area metals (Raney-Ni). The liquid phases are constituted by an alkane, water, and an ammonium salt. This kind of system was developed over the past 12 years, initially as an efficient and mild catalytic methodology for the hydrodehalogena-tion reaction of haloaromatics, after which it was sffidied for other kinds of reactions, and careful observation has resulted in a theory of modes of action whereby reaction rates, and selectivity, could be intensified. 

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