H_O_X_compounds_s09 - CHEM 1311A Syllabus Some descriptive...

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CHEM 1311A Syllabus Some descriptive chemistry of s- and p-block elements Compounds of hydrogen Compounds of oxygen and related elements Compounds of the halogens (halides) Acids and bases Redox chemistry of the elements Third Exam – Wednesday, March 25 Today is the deadline to apply for grade substitution for a course retaken in the spring or summer term (for those enrolled in summer) Today is also the deadline for dropping individual courses (W “grade” on transcript)
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Hydrogen Compounds Classification Synthesis Direct combination of the elements Protonation of a Br N nsted base Metathesis (double replacement) of a halide with a hydride Reactions Homolytic cleavage Heterolytic cleavage by hydride transfer Heterolytic cleavage by proton transfer Oxidation (gives E n O m and H 2 O except metallic and group 17)
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Classification of Hydrogen Compounds
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Synthesis: direct combination of the elements M (s) + H 2(g) X 2(g) + H 2(g) salt-like metal hydrides are among the strongest bases known N 2(g) + H 2(g)
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Synthesis: protonation of a Br N nsted base Mg 3 N 2 + H 2 O (3 Mg (s) + 2 N 2(g) Mg 3 N 2(s) ) heat Ca 3 P 2 + H 2 O CaC 2 + H 2 O Other examples of Br ϕ nsted bases include Na 2 O, Na 2 S, CaH 2 , NaO 2 CR Br ϕ nsted base – proton acceptor
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Magnesium Nitride Serves Up Ammonia Magnesium nitride (Mg 3 N 2 ) is a convenient source of ammonia for a host of reactions that produce nitrogen-containing compounds, a University of Cambridge research team reports ( Org. Lett. , DOI: 10.1021/ol801398z ). The stable low-cost commercially available reagent, which produces NH 3 when treated with water or certain alcohols, is an alternative to premade NH 3 solutions or gas cylinders that can be cumbersome to use on a small scale. Gemma E. Veitch, Katy L. Bridgwood, and Steven V. Ley demonstrated the utility of Mg 3 N 2 in methanol as a reagent for the direct conversion of a broad range of esters to primary amides (carboxamides). In a separate study, the researchers used Mg 3 N 2 to prepare dihydropyridines via the Hantzsch condensation of ethyl acetoacetate with various aldehydes in ethanol ( Org. Lett ., DOI: 10.1021/ol801399w ). Magnesium nitride was previously known to release ammonia in water, the researchers note, but it had not been used to generate ammonia in organic syntheses until now. The team is still exploring the scope of the method, Bridgwood says. A paper on the preparation of pyrroles will be published soon, she adds, and experiments involving pyrimidine synthesis from nitriles, nucleophilic aromatic substitution, and continuous-flow reactions are ongoing. Chem. Eng. News 2008 86 , 36-37
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Veitch, G.E.; Bridgwood K.L.; Ley, S.V. Org. Lett. 2008 10 , 3623 Use of Mg 3 N 2 with proton donor in synthesis
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Synthesis: metathesis (double replacement) of a halide with a hydride LiH + AlCl 3 NaH + BF 3 LiAlH 4 + SiCl 4 LiAlH 4 + BF 3 B H B H H H H H 3-center-2-electron bonds
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3-center-2-electron bonds Many examples in boron and aluminum compounds; most often hydrogen is bridging but sometimes carbon groups, i.e., CH 3 in compounds such as Al 2 (CH 3 ) 6
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This note was uploaded on 05/23/2011 for the course CHEMISTRY 1311 taught by Professor Cox during the Spring '10 term at Georgia Institute of Technology.

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H_O_X_compounds_s09 - CHEM 1311A Syllabus Some descriptive...

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