Carbon-sulfur double bond compounds acidity

Bromine is used as an analytical reagent to determine the amount of unsaturation in organic compounds because carbon—carbon double bonds add bromine quantitatively, and for phenols which add bromine in the ortho and para positions. Standard bromine is added in excess and the amount unreacted is deterrnined by an indirect iodine titration. Bromine is also used to oxidize several elements, such as T1(I) to T1(III). Excess bromine is removed by adding phenol. Bromine plus an acid, such as nitric and/or hydrochloric, provides an oxidizing acid mixture usefiil in dissolving metal or mineral samples prior to analysis for sulfur. 

Chlorine bleaches react with more chromophores than oxygen bleaches. They react irreversibly with aldehydes, alcohols, ketones, carbon-carbon double bonds, acidic carbon-hydrogen bonds, nitrogen compounds, sulfur compounds, and aromatic compounds. 

Examples of electrophilic reagents that normally add to carbon-carbon double bonds of alkenes to give saturated compounds include halogens (Cl2, Br2, and I2), hydrogen halides (HC1 and HBr), bypohalous acids (HOC1 and HOBr), water, and sulfuric acid ... 

Alcohol dehydration is an important reaction in the human body, where enzymes (rather than sulfuric acid) function as catalysts. For example, the dehydration of citrate is part of the citric acid cycle discussed in Section 13.5. Note that the dehydration of citrate, 2-propanol (Reaction 3.2), and 2-butanol (Reaction 3.3) all involve exactly the same changes in bonding. In each reaction, an H and an —OH are removed from adjacent carbons, leaving a C=C double bond. The other molecular bonds in all three of those compounds do not change ... 

If a carbon chain has four or more carbon-carbon bonds, we number the position of the double bond using the lower available number. Compounds with two or more double bonds take the suffix " diene" or "triene." For example, 1,3 butadiene is shown as CH2=CH-CH=CH2. Ethylene and propylene currently rank fourth and fifth in industrial chemical tonnage, just behind three inorganic chemicals (sulfuric acid, nitrogen, and oxygen). 

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