Haloalkanes alkene preparation from

In the preceding paragraphs we dealt with procedures where amino groups are introduced in the last step into halo- and alkoxyacetylenes which can eventually be prepared in situ by elimination from the corresponding haloalkanes and alkenes. 

In Chapters 11 and 12 we return to the presentation of a new functional group the carbon-carbon double bond. This functional group differs from those seen so far in that it hicks strongly polarized covalent bonds. Instead, its reactivity arises from specitil characteristics of electrons in so-called it bonds. The properties of the.se electrons and their consequences are discussed in the next chapter. Chapter 11 is restricted to a general description of alkenes as a compound class and a presentation of methods of preparation of double bonds. Most of the reactions are ones you have already seen, because the major methods of alkene syntheses are the same elimination reactions of alcohols and haloalkanes that were presented in Chapters 7 and 9. Only some finer details have been added. 

Unsaturated fatty compounds such as oleic acid [la], 10-undecenoic acid [2a], pet-roselinic acid [3a], erucic acid [4a], and the respective esters, alcohols, and native oils (Fig. 1) are alkenes and contain an electron-rich double bond that can be functionalized in many different ways by reactions with electrophilic reagents. It is therefore remarkable that >90% of oleochemical reactions have been focused on the carboxylic acid functionality and < 10% have been reactions of the alkyl chain and the C,C-dou-ble bond (1). A review on radical additions to unsaturated fatty compounds that appeared in 1989 (2) quoted only very few C,C-bond-forming reactions giving branched and chain-elongated fatty compounds. Since then, modem preparative radical chemistry has been developing and has been applied also to fat chemistry (3-5). We report here on radical additions of activated haloalkanes such as alkyl 2-haloalka-noates and 2-haloalkanenitriles to unsaturated fatty compounds [l]-[4] initiated by electron transfer from copper in solvent-free systems. These additions were also car-... 

PREPARATION OF ALKENES FROM HALOALKANES AND ALKYL SULFONATES BIMOLECULAR ELIMINATION REVISITED... 

In this chapter, we looked at alkenes, a compound class characterized by the carbon-carbon double bond. In Chapters 7 and 9, we learned that alkenes are prepared synthetically by elimination reactions of haloalkanes and alcohols, hi this chapter, we examined these reactions in more depth. We saw that the structure of the base determines what products will form in E2 elimination from haloalkanes. Similarly, the stracture of an alcohol undergoing acid-catalyzed dehydration determines what mechanism takes place and how easily it occurs. 

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