Heteroatom functional groups

Reactions in chloroaluminate(III) salts and other related binary salts often proceed smoothly to give products. However, it should be noted that these salts are water-sensitive and must be handled under dry conditions. They react with water to give hydrated aluminium(III) ionic species and HCl. When a reactant or product contains a heteroatomic functional group, such as a ketone, a strong ketone/alumini-um(III) chloride adduct is formed. In these cases, this adduct can be difficult to separate from the ionic liquid at the end of a reaction. The isolation of the product often... 

It is important to note that SNAr displacement reactions of heteroatom functional groups other than halides have been demonstrated on purine substrates, including mesitylenesulfonates <20000L927>, sulfones (see Section 10.11.7.5), nitro substituents <2006S2993>, and T-azoles (see Section 10.11.7.3.2). Halopurines have been reduced using sodium naphthalenide <1997T6295>. 

Most of the compounds that you have encountered in this text so far have been fairly simple. In addition to any carbon-carbon double or triple bonds, they have contained only one functional group and could be named by using suffixes such as -ynol or -dienone. However, for a compound that contains more than one heteroatom functional group, only one of these functional groups can be designated in the suffix. For example, consider the following compound, which has both alcohol and ketone functional groups ... 

Oxidation of Methylene to Heteroatom Functional Groups Other Than Oxygen or Carbonyl... 

A promising synthetic application for the metathesis reaction concerns unsaturated compounds containing heteroatom functional groups. Metathesis of functionalized acyclic olefins would allow single-step syntheses of various mono- and difunctional derivatives of hydrocarbons with well-defined structures (eq. (7)) X = functional group. 

Despite the fact that polar entities are catalyst poisons, a variety of acyclic olefins containing a heteroatom functional group can undergo metathesis in the presence of a suitable catalyst, although at a high catalyst level. These include unsaturated esters, ethers, ketones, amines, nitriles, halogens, etc. [14]. In particular metathesis reactions - including ethenolysis - of unsaturated fatty esters and fatty oils are of interest, as they have perspectives for the oleochemical industry [15]. 

Ketones with useful heteroatomic functional groups containing nitrogen 199 2121, oxygen[163, 213 2171, phosphorus12181 and sulfur11 4, 18+1 219-2271 have been reduced by biocatalysts. For example, an intermediate in the synthesis of p-lactam antibiotics was obtained by microbial reduction of a P-keto ester as shown in Fig. 5-39(a)(1991, while yeast reduction of a p-keto dithioester afforded an easily separable mixture of p-hydroxy-dithioesters, the major component of which was converted enantiose-lectively into a sex attractant of the pine saw-fly as shown in Fig. 15-39(b)12191. 

Olefin metathesis is being used increasingly in the specialty chemicals market. Olefin interconversion can be used to produce isomerically pure symmetrical internal olefins from a-olefins (Eq. 2 R H), and a-olefins can be produced from internal olefins via ethenolysis. Metathesis of olefins bearing heteroatom functional groups is also a very promising application of the metathesis reaction, which enables the synthesis, in only a few reaction steps, of many products that would otherwise be difficult to obtain. 

C. Lithium Aluminum Hydride Reduction of Non-Carbonyl Heteroatom Functional Groups... 

One last piece of information is required for synthesis in order to manipulate functional groups. In those cases where a heteroatom functional group interferes with a transformation and cannot be removed, modified, or inserted earlier or later in a synthesis, methods are available to temporarily block it. This method is termed protection and the moiety used to block the reactive fragment is called a protecting group, which will be the focus of Chapter 7. 

Similar electronic reasons discussed for Bronsted-Lowry bases predict that an ether is a stronger Lewis base than an alcohol. Interestingly, the alkyl halide is a reasonably good Lewis base with BFg, forming 55. Although 55 is much more reactive (less stable) than 54 or 53, a species such as 55 can be generated and used in chemical reactions. In the case of an alkene and an alkyne, the carbocations 56 and 57 are quite unstable, and if formed at all will be very reactive (see Chapter 10, Section 10.6). Compared with the heteroatom functional groups, alkenes and alkynes are poor Lewis bases. Nonetheless, there are reactions in which they do react as Lewis bases (see Chapter 10, Section 10.6). 

Boiling point is defined as the temperature at which a liquid and the vapor (gas) above it are in equilibrium. At normal atmospheric pressure, the boiling point of a liquid will be the temperature at which the liquid is at equilibrium with the atmosphere above the liquid (atmospheric pressure). Another way to say this is that boiling point is the temperature at which molecules leave the liquid phase and are moved into the gas phase. Several factors are important in determining the boiling point of a liquid. The number of atoms in a molecule and the number and type of heteroatom functional groups will play an important role. 

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