Portmess Homework Q&S 84

Portmess Homework Q&S 84 - ) ( c ) ( d ) ( e ) 4.32 ( a...

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( b ) As described in part ( a ), K a 5 10 2 p K a , therefore K a for vitamin C is given by the expression: K a 5 10 2 4.17 5 6.7 3 10 2 5 ( c ) Similarly, K a 5 1.8 3 10 2 4 for formic acid (p K a 3.75). ( d ) K a 5 6.5 3 10 2 2 for oxalic acid (p K a 1.19). In ranking the acids in order of decreasing acidity, remember that the larger the equilibrium constant K a , the stronger the acid; and the lower the p K a value, the stronger the acid. Acid K a p K a Oxalic (strongest) 6.5 3 10 2 2 1.19 Aspirin 3.3 3 10 2 4 3.48 Formic acid 1.8 3 10 2 4 3.75 Vitamin C (weakest) 6.7 3 10 2 5 4.17 4.30 Because the p K a of CH 3 SH (11) is smaller than that of CH 3 OH (16), CH 3 SH is the stronger acid of the two. Its conjugate base (as in KSCH 3 ) is therefore weaker than the conjugate base of CH 3 OH (as in KOCH 3 ). 4.31 This problem illustrates the reactions of a primary alcohol with the reagents described in the chapter. ( a ) ( b
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Unformatted text preview: ) ( c ) ( d ) ( e ) 4.32 ( a ) This reaction was used to convert the primary alcohol to the corresponding bromide in 60% yield. ( b ) Thionyl chloride treatment of this secondary alcohol gave the chloro derivative in 59% yield. COCH 2 CH 3 CH 3 O OH COCH 2 CH 3 CH 3 O Cl SOCl 2 pyridine CH 2 CH 2 Br PBr 3 pyridine CH 2 CH 2 OH CH 3 CH 2 CH 2 CH 2 OH CH 3 CH 2 CH 2 CH 2 Cl 1-Chlorobutane SOCl 2 CH 3 CH 2 CH 2 CH 2 OH CH 3 CH 2 CH 2 CH 2 Br 1-Bromobutane PBr 3 CH 3 CH 2 CH 2 CH 2 OH CH 3 CH 2 CH 2 CH 2 Br 1-Bromobutane NaBr, H 2 SO 4 heat CH 3 CH 2 CH 2 CH 2 OH CH 3 CH 2 CH 2 CH 2 Br 1-Bromobutane HBr heat CH 3 CH 2 CH 2 CH 2 OH 1 NaNH 2 CH 3 CH 2 CH 2 CH 2 O 2 Na 1 1 NH 3 Sodium butoxide 78 ALCOHOLS AND ALKYL HALIDES...
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This note was uploaded on 09/20/2011 for the course CHM 2210 taught by Professor Reynolds during the Spring '01 term at University of Florida.

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