Massachusetts Institute of Technology Organic Chemistry Hour Exam #1. Name. Official Recitation Instructor

Transcription

1 Massachusetts Institute of Technology rganic Chemistry. Friday, September 0, 00 Prof. Timothy F. Jamison Hour Exam # Name (please both print and sign your name) fficial Recitation Instructor Directions: Closed book exam, no books, notebooks, notes, etc. allowed. However, calculators, rulers, and molecular model sets are permitted. Please read through the entire exam before beginning, in order to make sure that you have all the pages and in order to gauge the relative difficulty of each question. Budget your time accordingly. Show all of your work if you wish to receive partial credit. You should have pages total: exam pages including this page, pages of reference information, and blank pages for scratchwork. Question: Grader:. / 40 points. / 0 points. / 0 points Total: / 00 points

2 . (40 points total points each) The molecular formulas and H NMR spectra of 8 common organic solvents are provided below and on the following pages. For each, neatly draw the entire structure (i.e., not the acronym) in the box provided. In some cases, relative integration values (circled numbers) and/or other information have been provided. Note: Do not represent functional groups with partial molecular formulas or other abbreviations. For example, do not use Ph or C H for a phenyl group. Draw the entire group (including hydrogen atoms). a. C 7 H b. CH8,d Septet

3 c. C H d. CHN e. CH7N, s, s, s

4 f. C 4 H 8,t q, g. C4H0,q, t h. C 4 H

5 . (0 points total) Answer the questions below about the structure that has the following data: EA C, 8.; H,.0; N, 7. MS 9, 7. C NMR.7,., 8.9,.,.9 H NMR 7.9 (t, J = 7.8, H), 7.4 (d, J = 7.8, H),.4 (s, 8H) a. (0 points) Determine the molecular formula. Circle your final answer. b. ( points) Calculate the Index of Hydrogen Deficiency (IHD). Circle your final answer. c. ( points) How many types of carbon (chemically non-equivalent) does this compound have? Circle your final answer. d. ( points) How many types of hydrogen (chemically non-equivalent) does this compound have? Circle your final answer. e. (0 points) In the space below, draw the structure of the molecule that is consistent with all of the data provided. Circle your final answer.

6 . (0 points total) Answer the questions below about the structure that has the following data: EA C, 7.9; H, 8.80 M + 0 IR 40 (broad), 70 (strong) C NMR 8.4, 40.9, 7.0, 9., 7.4, 4.9, 44., 0.,., 8. H NMR.9 (broad s, H), 7. (d, J = 7.7, H), 7.09 (d, J = 7.7, H),.70 (q, J = 7.0, H),.44 (d, J =.8, H),.84 (nonet (9 lines), J =.8, H),.49 (d, J = 7.0, H), 0.89 (d, J =.8, H) a. (7 points) Determine the molecular formula. Circle your final answer. b. ( points) Calculate the Index of Hydrogen Deficiency (IHD). Circle your final answer. c. (8 points) Which protons are coupled to which? Complete the tables below using the NMR data above. Write H, H, etc. or none, as appropriate, in the box provided, and list all protons to which a given proton is coupled. Proton(s) () Coupled to Proton(s) () Coupled to H.9 H.44 H 7. H.84 H 7.09 H7.49 H4.70 H d. (0 points) Draw all of the possible enantiomers and diastereomers of the unknown compound that are consistent with all the data given. Circle your final answers. e. (Extra credit points total) What is the common name of this over-the-counter pharmaceutical ( points), and for which symptoms is it indicated ( points)?

7 - X-H Region Phenols and Alcohols Infrared Spectra: Tables of Reference RH sharp or broad(h-bonded) Acids RC H very broad Amides and Amines C-H bonds sp Region RCNHR R NH C C H C C H C C H RCH Acetylenes Nitriles Ketenes Allenes Double Bond Region Alkenes Imines Nitro Carbonyl Groups C C C N C C C C C C C C N N Note: subtract ca. 0 cm - for conjugation (e.g. with a double bond or aromatic ring) weak unless conjugated (two bands) Ketones R C 70 (subtract ca. 0 cm - for conjugation) Anhydrides RC()CR Acid Chlorides RCCI Esters Acids RC R RC H Amides RCNR Urethanes R NC R Aldehydes RCH , (two bands) membered and larger cyclic ketones NR NR 0

8 δ 4-4 H NMR Spectra: Tables of Reference Average Chemical Shifts (δ) of α Hydrogens in Substituted Alkanes* X CH X RCH X R CHX Chemical Shifts of Hydrogens Bonded to Unsaturated Centers Type Unconjugated Conjugated* H CH or CH F Cl Br I H R Ar CR CRAr SH SR SR S R NR NR-Ar NCR N CH CR CAr CH CR CNH CR=CRCR Phenyl Aryl δ.0-. C CR.0 C CN.0..7 * The tabulated values are average values for compounds that do not contain another functional group wlthin two carbon atoms from the indicated hydrogens. δ Includes polycycllc and many heterocyclic SH Aliphatic.-.7 aromatics. Aromatic.-4 δ R C=CH R C=CHR Aromatic.-8. Nonbenzenoid aromatic.-9.0 Acetylenic Aldehydic R NCH RCH * The position depends on the type of functional group in conjugation with the unsaturated group. Chemical Shifts of Hydrogen Bonded to xygen, Nitrogen, and Sulfer Functional Group H Akohols Phenols Enols RC H H-bonded to C= NH Alkylamine 0.-. NH R NH + Arylamine Amide Alkylamine, Arylamine Ammonium salts Chemical Shift, δ 0. (Monomeric) 0.- (Associated) 4. (Monomeric) 4.-8 (Associated). 9- (Dimeric) (in CF CH)

9 Characteristic Functional Group Chemical Shifts In C NMR () Alkanes rganohalogen Methyl (RCH ) Methylene (RCH R') C F C Cl Methine (RCH(R')(R")) - C Br 0-40 Quaternary (RC(R')(R")(R"')) 0-40 C I -0-0 Alkanes 00-0 Ketones, Aldehydes 8-0 Aromatic 0-0 Carboxyl Derivatives Alkynes Acids 0-8 Nitriles 0- Esters -80 Alcohol, Ethers 0-90 Amides 0-80 Amines 40-0 Carbamates 0-0