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Unformatted text preview: Massachusetts Institute of Technology Organic Chemistry 5.13 September 10, 2003 Prof. Timothy F. Jamison Problem Set #1 Organic Structure Determination DUE DATE: Thursday, September 18, 2003 at 12 noon NOTE: If mass spectrometry (MS) data are provided, the highest molecular ion given corresponds to the molecular ion (M‘), unless otherwise noted. In class we derived a formula for calculating the “index of hydrogen deficiency,” which is equal to the sum of the number of rings and n—bonds in an organic molecule. We showed that num . - - us of each element is multiplied by a factor (hereafter called “deficiency factor”) in this eq . O: 0, etc.). a. Derive the deficiency factor for phosphorus (P), using triphenylphosphine (CGH5 laboratory reagent (e.g. Wittig reactions), as the basis for your calculations. b. Derive the deficiency factor for phosphorus (P), using triphenylphosphine oxide byproduct in the Wittig reaction), as the basis for your calculations. 0. Why are the two factors derived different? In other words, what do you need to know about each element In a particular organic molecule? Based on these considerations, write a general mathematical expression for the deficiency factor for any element. . OXlDPrT/TDU W11? err "VAl/BJCE" X to ’ DR) S TE— a. Draw the structures of the 4 compounds that satisfy the following experimental data: l EA (found): C, 60.96; H, 15.35; N, 23.70 MS: 59 b. There is a broad signal at 2 70 cm‘1 in the lR spectrum of this unknown compound. Which of the structure(s) that you drew r your answer to 2a can you eliminate from consideration based on this information? Explain. l NNHz Afi/ AWL /N\ N ' H /,\) \ (N O A) ., H W3) (It was) a. Draw the structures of the 6 molecules that satisfy all of the following experimental data, including enantiomers, diastereomers, alkene Isomers: 0H EA (found): C, 66.63; H, 11.18 \ §;\ Moi-L Moll MS: 72 OH IR: 3435 (brgad), 16457meak) M 0“ \\I’/\OH b. When this unknown compound is treated with pyridinium chlorochromate, the signal at 3435 cm‘1 disappears from the IR spectrum, and a strong, sharp signal at 168 cm‘1 appears. Which of the structures(s ) that you drew for your answer in 3a can you eliminat rom consideration based on this information? A’W QCEPT c. Howwouldyoudistinguish bWainingstructures? lily " 36 ) 0” A166) memob - \\ 6- \\./\ W DIST New) ISHGS Wlomg (Vi/WW WMS) fin? C0639 SWK/Ific (LOW—ZN llU 4. In the following problems, determine the structure of each unknown: a. EA (found): C: 73.43; H, 10.27 , :1 MS: 98 CbH’OO MD 2‘ W W 13C NMR:2 6.2, 43.0, 32.0, 25.8. _J (Mfg'él) C30 Witt/«LYL— 0/7 2 W CQU'V b. EA (found) c, 93. 06; H, 6.94 Ms:,116 77 (4H? ZERO 3% QEC '\ IR: 2075 w(eak) a / “Wu (MT (EC-H) CNMR:1321,128.2,128.1,122.3,6.8,81.01.1. L: bw MWUYL c. EA (found).C, 66.63, H,11.16 C H80 :r/wt) - Q) MS:72 4; \JKH ‘30 NMR220’?.7,45.8,14.5. 3 DIFF (3C 1 C30 (WI-Ell #0 W0?) 8‘3ng 5. When treated with lithium aluminum hydride' In tetrahydrofuran, two isomeric compounds1( I(R: 1735 2 on 1)and 2 (IR. 1705 cm ) (bah—Teach gave two different products( i..e all 4 prod ' 00ch the 2 react are different from one nother) Deduce thes ructures of 1 and 2. M bo‘H/I IHD: 5' WINK AWL.) CW 179 WWW, 341,00 6. Compounds A and B were both treated with NaOH, producing a single compound, 0 O CH CH 3 3 H O— + ——-—-> C 3, heat A 0H B 0H Data for C: EA (found): c: 73.15%; H: 7.37% 1"’C NMR: 210.1, 164.6, 134.5, 34.0, 29.0. a. What is the relationship of A and B? DKASTBTEOWI (EV—S b. Using the data provided above and the spectra provided below, deduce the structure of C. ‘ / 0. Write out a stepwise mechanism that accounts for the formation of C. e 0 O Q? 0\ GI?) \\ H \\ 7 336% _. 1130 s 115/ .._.> Q 45$ 6 (4ch) 114 39 fi ” 2 H R Hoj D b 7. Compound D, the product of the reaction below, was characterized by 1H NMR and 13C NMR (spectra below). Draw the structure of the product and a stepwise mechanism for its formation in this reaction. OH H. O + H3C CH: ——-> Compound D CH3 \‘4 H OH 1H NMR of co nd D (truncated, nothing downfield of 3 ppm): 13C NMR of compound D: A'L2\O( L, }H 5* QR S O IN {E} “ ® 5 i I u i 0 Vilzoo 150 ' ' '100 r 50 T 0 011 PP“ :OH “E? {8 Z 99/ _> J/\ + ‘3 %\{©H v my“; —§ *"7 *K ® —1— H, 8. a. Propose two possible structures’for Compound E using the information provided below. CH leol,‘L €5A(round):c;75.o1°/o;wasatl’ém won/41>”0-9. MWL‘YL) DA’W ~IWT mums 574m? w 95217601129 MS: 176, 16PC-0‘433 VALUES 130 NMR: 166.9, 144.5, 134.4, 130.1, 128.8, 128.0, 118.2, 60.4, 14.3. «527 J Adz/we? Armem’c 3-9 N MWL b. The coupling constant between the signals at 6.4 . um and 7.8 ppm in the 1H NMR spectrum is 15 Hz. Based on this information, which of - - L2 ikely to be the structure of E? Exo . VS. § 001% 9. Sometimes it is possible to determine the structure of an organic molecule even with what appears to be an incomplete set of information. Using the data below, propose a structure for compound F. r g EA (found): c: 75.99%, H: 9.02% \ k 395 ADTE FOR. 870;. MS: 93, 92. (The molecular ion was not observed.) / [email protected] 1H NMR: sharp singlet (1 H) at 2.? ppm, broad singlet (1 H) at 2.38 ppm, all other signals between .5 a 2.0 ppm. CEC—® 13C NMR: signals, all between 0.0 and 90.0 ppm. (“Wave—(b 3900 QMJ') IR: very road, vRy strong signal ntered at 3400 cm“, weak“signal at 2110 cm". Wu Au. M100, 0‘1 H o \ =3. 6%”‘5 ALF—YNYL 2 7. Mag WurUWh/T 10. Propose a structuretfor compound G using the information provided below: 10 MS: 100, 85 C— 0143) m ALLWL, W 13C NMR: 215.2, and 4 other signals, all between 0.0 and 45.0 ppm (5 signals total). 56:0 ’t 90 AT 0508' Vt C t) (556 WW PM) (:5- MGR/(M [O] CWT/HOBO CAD EMA) (00 m3 ’Afl/ MST i 0K} WU? M WT d. {pa-rover (AIDA/-(ang) \3 C. M W1” 4 DlF’F. Aum/ Mme/us ' W 0:: iii" FOIZ‘CgH‘aoi ) [MW : 315+ ‘3(¢) 2 NW) ‘&:%_9[ (IMNSSlgufl . CQHLKOIL [MW : VHKSOAIABEE ' C1H‘koi 1 MW = (00 +3<¢> a/OO => (‘3 :0 IMPOSSIBLF (HAVE 0H3 (mm)? (M3)) ‘ $0 *7: s (o . CSHXOL 2 mw: ?2+ 3(8): (80 3533? WON/WW, Bur woo» HAvc’To HAVE? 2 WW 0:0 Qcéflsz$)) LEW/Wk OVW 3 wow Sum/ALE. :5 MDT CngOL ‘— [a :—> C(oHYLO IHD :: i ;_) C50 + CSHIZ (NO KIA/(2’3) \/v\/ ALL ML, ...
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