GRE Subject Test: Chemistry : Sulfide Chemistry

Study concepts, example questions & explanations for GRE Subject Test: Chemistry

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Example Questions

Example Question #1 : Sulfide Chemistry

Which of the following amino acids can participate in the formation of a disulfide bridge?

Possible Answers:

Aspartic acid

Alanine

Phenylalanine

Cysteine

Tyrosine

Correct answer:

Cysteine

Explanation:

Cysteine's R-group contains a sulfhydryl group (-SH), which can participate in the formation of a disulfide bridge in a protein's tertiary and/or quaternary structure. Cysteine is the only amino acid to contain a sulfur atom.

Example Question #1 : Hydrocarbon Reactions

Which substrate, when subjected to ozonolysis followed by treatment with dimethyl sulfide, would give only one hydrocarbon product?

Possible Answers:

4-octene

2-octene

3-octene

1,7-octadiene

1,3-octadiene

Correct answer:

4-octene

Explanation:

Ozonolysis is essentially used to cleave a compound at the location of a double bond. For the result to be a single product, the cleavage must occur at a point of symmetry.

4-octene, a symmetrical alkene, would give two equivalents of butanal upon ozonolysis. All of the other compounds are unsymmetrical and would give at least two different non-identical products.

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