Alkanes ketones

Raney nickel desulfurization of thiophenes is an important technique of chain extension. Ring fission is accompanied by saturation of the ring carbon atoms and chain extension by four carbon atoms is effected. This method has been widely used to prepare alkanes, ketones and carboxylic acids and their derivatives (B-74MI30200). An illustrative example is given in Scheme 38 see also CHEC 1.16 and CHEC-II(2)522. 

Svstem Method Amide Alkane Ketone Amine RE... 

Ni Alcohols, toluene 5 to 100 3-10 alkene —> alkane ketone —> alcohol aldehyde -> alcohol... 

The product of this reaction can be used to synthesize a variety of organic compounds. For example, the nucleophilic attack of [Fe(CO)4] on an organic halide RX yields [RFe(CO)4], which can subsequently be converted to alkanes, ketones, carboxylic acids, aldehydes, acid halides, or other organic products. These reactions are outlined in Figure 14-5 note that [RFe(CO)4] undergoes other types of reactions in addition to nucleophilic displacements, as shown for some examples in the figure. Additional details of these reactions can be found in the literature. ... 

In their chapter [43], K m n and P kanyi discuss main-part isostructurality of cardiotonic steroids. Here, we discuss experimentally measured solid-phase enthalpies of formation of steroids possessing a common (5a)-androstane skeleton (anh-anft-anft-perhydrocyclopenta[a]phenanthrene). The enthalpies of formation are listed in Table 2. The steroids shown later in Schemes 1 and 2 are related by simple formal reactions which interconvert the various substructure functional groups alcohol <=> ketone, alkene alkane, alkane <=> alcohol, and alkane ketone. The difference between the enthalpies of formation of two steroids is the enthalpy of reactionfs) which interconverts them (Eq. 31) ... 

The composition of hpids on the surface of leaves, stems, and fruits is quite different from that of hpids that form intracellular membranes. Their role is the protection of sensitive plant tissues against the loss of water and other biologically important volatiles. Waxes (i.e., esters of FA with monofunctional alcohols) are the most important components of these lipids. Some plant waxes are of commercial importance, such as camauba or candellila wax. They are solid at room temperature and in temperate climates, with the exception of liquid jojoba wax, and are plastic or even liquid in tropical climates. They contain bound saturated long-chain FA and alcohols. Waxes on the surface of apples and other fruits from temperate zones are solids or semisolid pastes, consisting of terpenes, ceryl cerotate, ceryl palmitate, and other esters. In the wax from lettuce leaves, higher alcohols prevail, with only small amounts of free FA (Bakker et al., 1998). Other components, such as alkanes, ketones, esters, secondary alcohols, were detected in other vegetables (e.g., in kale or rutabaga). 

VTPR- model (----) for different alkane—ketone systems. 

Recall that the electronegativity of C and H are roughly the same, but that O has a significantly higher electronegativity. For each type of compound (alkane, ketone, alcohol) predict whether or not the compound is expected to be polar or nonpolar. 

Cycloreversion reactions, especially the retro-Diels-Alder reaction, also yield diagnostic product ions. Fragmentation reactions of each class of compounds (e.g., alkanes, ketones, alcohols, esters) are also discussed (Section 6.6). Upon El, each class of molecules fi agments in a typical fashion that can identify the precursor structure. 

For the system z-butanone-n-hexane the predicted results of the excess enthalpy using UNIFAC are shown in Figure 5.82 together with the experimental data. It can be seen that the predicted excess enthalpies are not in agreement with the experimental values. This means that an extrapolation to high or low temperatures wiU produce incorrect results. The same is true for all other alkane-ketone systems, as shown in Figure 5.86. 

Figure 5.81 Experimental [3] and predicted VLE data foi alkane-ketone systems using UNIFAC.

Figure 5.86 Experimental [3] and predicted excess enthalpies for different binary alkane - ketone systems ------original UNIFAC — modified UNIFAC...

A major feature of acetone noted previously is that, along with isopropyl alcohol (IPA), it is considered a universal solvent. This means that acetone and IPA are fiilly miscible with a wide range of compounds within solvent classes such as alkanes, chlorinated alkanes, ketones, and—most inqiortantly— water. Consequently, for those support materials that are used as either NP or RP supports (e.g., cyanqiropyl, aminopropyl, diol), acetone (w IPA) may be used as a conversion solvent For example, to change a cyanopropyl colunm from a NP hexane/ dichloromethane mobile phase to a RP acetonitrile/water system, acetone (or IPA) is equilibrated with the column as an intermediate step. Note that buffers should never be present in any solution during the conversion step. If a buffer is in the mobile phase, then an identical mobile phase without the buffer must be equilibrated with the column prior to the conversion step. 

The products of oxidation include shorter-chain fatty acids, fatty add polymers, aldehydes (alkanals), ketones (alkanones), epoxides and hydrocarbons. The acids and afkanals are major contributors to the smells and flavours assodated with oxidised fat, and they significantly reduce its palatability. The potency of these compoimds is typified by deca-2,4 dienal, which is detectable in water at concentrations of as httle as 1 in 10 000 million. 

Gmehling, (. (1993) Excess enthalpies for 1,1,1-trichloroethane with alkanes, ketones, and esters./. Chem. Eng. Data, 38,143-146. 

A key additional advantage of both SAFT-y and GC-SAFT-VR is that mixtures can be treated in a fully predictive marmer without the need to propose combining rules and adjustable parameters. In this context both methods have been shown to provide a good description of the pressure and composition of mixtures including binary mixtures of alkanes, alkenes, alkanols, namely (alkanes + alkylbenzenes), (alkane + ketones), (alkane + esters), (alkane + adds), (alkanes + amines) and even cases with highly non-ideal behaviour including liquid-liquid equilibrium (LLE) and polymer systems. ... 

Trimethylaluminum exhaustively methylates tert. alcohols to alkanes, ketones to g m-dimethyl compds., and carboxylic acids to tert-butyl compds. - E Excess trimethylaluminum allowed to react... 

---