Acidity of 1-alkynes

The acidity of the alkynyl hydrogen is strongly influenced by the nature of the group on the other side of the triple bond, as shown in Table 8.3.92 When the R group is electron releasing (e.g., an alkyl group such as 

Chapter 8. Nucleophilic Species That Form Carbon-Carbon Bonds 

The physical properties of alkynes resemble those of alkenes and alkanes. Table 3.5 collects some data. 

It is generally most difficult for even a strong base (B ) to remove a proton from a hydrocarbon to give an anion. In other words, hydrocarbons are generally very weak acids. We have already had a brief discussion of the methyl anion in Chapter 2 (p. 62), but methane, the parent of this anion, is an extraordinarily weak acid (Fig. 3.63).  

FIGURE 3.63 Strong bases (Bs ) can remove a terminal hydrogen of an acetylene. Terminal acetylenes are reasonably strong acids (for hydrocarbons). 

C is hybridized approximateiy sp , therefore the nonbonding eiectrons are in an orbitai of about 25% s character 

FIGURE 3.64 In an acetylide ion, the two nonbonding electrons are accommodated in an sp orbital. 

A hydrogen atom on a triply bonded carbon is weakly acidic and can be removed by a very strong base. Sodium amide, for example, converts acetylenes to acetylides. 

This type of reaction occurs easily with a hydrogen attached to a carbon-carbon triple bond (i.e., RC=C—H), but less so when the hydrogen is adjacent to a double or single bond. Why Consider the hybridization of the carbon atom in each type of C—H bond  

Conduct research on the Internet to find more information on petroleum and to answer the following questions. 

How much oil does the world use in a year What percentage of U.S. energy needs is supplied through oil  

What are some of the earliest known examples of oil use by humans When did the modern oil industry come into being  

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ALKENES AND ALKYNES II. OXIDATION AND REDUCTION REACTIONS. ACIDITY OF ALKYNES... 

Alkenes and Alkynes II. Oxidation and Reduction Reactions. Acidity of Alkynes... 

Introduction 392 9-2 Nomenclature of Alkynes 393 9-3 Physical Properties of Alkynes 394 9-4 Commercial Importance of Alkynes 395 9-5 Electronic Structure of Alkynes 396 9-6 Acidity of Alkynes Formation of Acetylide Ions 397 9-7 Synthesis of Alkynes from Acetylides 399 9-8 Synthesis of Alkynes by Elimination Reactions 403 Summary Syntheses of Alkynes 404 9-9 Addition Reactions of Alkynes 405... 

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