Guided course 00:50Calculating Enantiomeric Excess and Observed RotationJohnny Betancourt1527views11rank1comments
Guided course 03:59Calculating Enantiomeric Excess and Observed RotationJohnny Betancourt1379views18rank5comments
Open QuestionCalculate the observed rotation of a chiral mixture that contains 65% (S)-stereoisomer where the [α] of pure (S)-stereoisomer = -118.441views4rank3comments
Open QuestionAn optically pure (R)-stereoisomer of a molecule has a specific rotation of – 20°. What specific rotation would be observed for a mixture of the (R) and (S) stereoisomer where there is an enantiomeric excess equal to (S) 60%.713views5comments
Multiple Choice If a mixture of R and S enantiomers has an ee of 80% R, what is the ratio of R and S enantiomers in the mixture?343views
Textbook QuestionA solution of an unknown compound (3.0 g of the compound in 200 mL of solution), when placed in a polarimeter tube 2.0 dm long, was found to rotate the plane of polarized light 18° in a counterclockwise direction. What is the specific rotation of the compound?472views
Textbook QuestionThe observed rotation of 2.0 g of a compound in 50 mL of solution in a polarimeter tube 20 cm long is +138°. What is the specific rotation of the compound?818views1rank
Textbook Question(+)-Mandelic acid has a specific rotation of +158. What would be the observed specific rotation of each of the following mixtures? c. 75% (-)-mandelic acid and 25% (+)-mandelic acid851views
Textbook QuestionA chiral sample gives a rotation that is close to 180°. How can one tell whether this rotation is +180° or -180°?1093views1rank
Textbook Question(+)-Tartaric acid has a specific rotation Of +12.0°. Calculate the specific rotation of a mixture of 68% (+)-tartaric acid and 32# (-)—tartaric acid.2377views
Textbook QuestionA solution of 2.0 g of (+)-glyceraldehyde, HOCH2CHOHCHO, in 10.0 mL of water was placed in a 100-mm cell. Using the sodium D line, a rotation of +1.74° was found at 25 °C. Determine the specific rotation of (+)—glyceraldehyde1111views1rank
Textbook QuestionA chemist finds that the addition of (+)-epinephrine to the catalytic reduction of butan-2-one (Figure 5-17 ) gives a product that is slightly optically active, with a specific rotation of +0.45°. Calculate the percentages of (+)-butan-2-ol and (−)-butan-2-ol formed in this reaction.765views
Textbook QuestionWhen optically pure (R)-2-bromobutane is heated with water, butan-2-ol is the product. The reaction forms twice as much (S)-butan-2-ol as (R)-butan-2-ol. Calculate the e.e. and the specific rotation expected for the product.279views
Textbook QuestionA student wanted to measure the specific rotation of the following propionate derivative (density = 1.12 g/ml). A sample of the pure compound was placed in a 10.0-cm polarimeter tube, and using the sodium D line, the observed rotation at 20°C was determined to be +46.6° . What is the specific rotation of the propionate derivative?369views
Textbook QuestionUsing a 1.0-cm polarimeter cell and a solution prepared by dissolving 2.54 g of glucose in 1 L of H₂O, the specific rotation of d-glucose was calculated to be +52.7° at 20 °C using the sodium D line as the source of light. What was the observed rotation of the solution?329views
Textbook Question Cholesterol (50 mg) was dissolved in 10 mL of chloroform and placed in a 1.0-cm polarimeter cell. This solution produced an observed rotation (using the sodium D line at 20°C ) of - 1.58° . What is the specific rotation of cholesterol?274views
Textbook QuestionThe α- and β-anomers of glucose are shown here. In solution, these two epimers can interconvert through a process called mutarotation. Assessments 27.68–27.73 refer to mutarotation. (•) Given that α-d-glucose has a specific rotation of + 112.2° , why is the specific rotation of β-d-glucose not -112.2°? What molecule would have a specific rotation of -112.2°?299views
Textbook Question(•••) Upon dissolving α-d-glucose or β-d-glucose in water, the specific rotation gradually changes, eventually reaching +52.6° for both solutions. Explain what is happening here.312views
Textbook QuestionQuestions (a)–(d) all refer to the following reaction, which has been engineered to produce one enantiomer to the exclusion of the other. <IMAGE>(c) Suppose the difference in activation energy is 1.6 kcal/mol. At what temperature would you produce C in 99% ee?313views
Textbook Question(•••) A chemist prepared a racemic mixture of the enantiomeric sulfonic acids shown here. Suggest two ways that these might be separated.300views
Open QuestionWhen 0.200 g of lactose is dissolved in 10.0 ml of water and placed in a sample cell 10.0 cm in length, the observed rotation is +2°. Calculate the specific rotation of lactose.90views
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