Butene spectrum

Figure 22 shows the spectrum in the OH region for zinc oxide after admission of butene-1 at a pressure of about 8 mm (14). Spectrum (a), taken after 8 min exposures, shows two features (1) the strong surface hydroxyl band at 3615 cm-1 is shifted about 5 cm-1 to lower frequencies (2) a new band appears at 3587 cm-1. This new band, clearly an OH, appears to arise from dissociation of the adsorbed butene. Spectrum (b) shows the same region after exposure to the gas phase for 1 hr. It is clear that the OH band formed from butene grows with time detailed studies, however, reveal that there is little change after the first 20 min. Spectrum (c) was taken after 20 min evacuation. Two features are evident (1) in the absence of the gas phase the hydroxyl band of the zinc oxide has shifted back to its previous position (2) the OH band formed from butene is reduced somewhat in intensity. Spectrum (d) was taken after degassing for 90 min ... 

Figure Bl.7.5. (a) MIKE spectrum of the iinimoleciilar decomposition of 1-butene ions (m/z 56). This spectrum was obtained in the second field-free region of a reverse geometry magnetic sector mass...

The 1H NMR spectrum shown is that of 3-methyl-3-buten-l-ol. Assign all the observed resonance peaks to specific protons, and account for the splitting... 

Methyl-3-buten-l-ol, NMR spectrum of, 647 Methylcyclohexane, 1,3-diaxial interactions in, 123 conformations of, 123 mass spectrum of, 4H molecular model of, 123, 293... 

From 446 mg (2.12 mmol) of l-(4-mcthylphenylsulfonyl)-2-butene EjZ >99.5 0.5) in TIIF containing 1.14 g (6.4 mmol) of HMPA and 192 mg (2.39 mmol) of 2-cyclopcnlenone at — 70 °C is obtained a colorless viscous oil, a H-NMR spectrum of which indicates a 95 5 mixture of the a-l,4-adduct/y-l,4-adduct. Preparative TI.C (ethyl acetate/petroleum ether 3 2) gives a 95 5 mixture of diastereomers of the title compound yield 556mg (88%). 

A singlet precursor has, however, been proposed for 4,4,4-triohloro-2-methyl-1-butene (17) produced in the photolysis of isomesityl oxide (18) in carbon tetrachloride solution on the basis of its all-emission spectrum (DoMinh, 1971). There remains some ambiguity, however, about the detailed route by which 17 is formed. Moreover there is other evidence suggesting that ketone photolysis in carbon tetrachloride is different CI3C. CHaCiMe) CHa CH3. CO. CHa. C(Me) CHa... 

Photochemical [2h-2] cycloadditions of olefins occur with retention of configuration according to the Woodward-Hoffmarm rule [6,7], These are excited-state reactions in the delocalization band of the mechanistic spectrum. A striking example of the symmetry-allowed reaction was observed when the neat cis- and tran -butenes were irradiated (delocahzation band in Scheme 3) [8],... 

The fact that we have three olefinic hydrogens means that our compound is a primary olefin, the fact that the other two carbons are both methylene carbons means that our substituent, bromine, is terminal. Thus the only possibility we have is that we are dealing with 4-bromo-1-butene (try to find another isomer that fits ). But this simple molecules has a highly complex proton spectrum, which can only be interpreted completely (exact chemical shift, coupling constants) by spectrum simulation. 

Figure 3. Series of IR spectra illustrating how the absorptions (spectrum e) of coordinated 1-butene were identified ...

Figure 23a shows the C—H region of the spectrum about 10 min (solid line) and 60 min (dotted line) after admission of 8 mm of butene-1 to a sample of zinc oxide. These spectra, which are primarily due to physically adsorbed and gas-phase butenes, show sizeable changes as a function of time. The region above 3000 cm-1 is particularly clear cut. Initially, a band is observed only at 3082 cm-1 this corresponds closely to the 3086 cm-1 band for gaseous butene-1 (64). After 1 hr the band at 3082 cm-1 is gone and two new bands (above 3000 cm-1) have appeared at 3035 and 3018 cm-1 which correspond within the experimental uncertainty to the expected bonds for cfs-butene (64) (3030 cm-1) and frans-butene (64) (3021 cm-1). Other bands are consistent with these changes. Thus, it is evident that double-bond isomerization has occurred. 

The most notable feature of these intrazeolite photooxygenations (Fig. 30) is that the oxygen CT band experiences a dramatic bathochromic shift in comparison to solution. This was detected initially by recording the product growth as a function of irradiation wavelength (laser reaction excitation spectrum)98,110 and was later verified by direct observation using diffuse reflectance UV-Vis spectroscopy.111 For example, 2,3-dimethyl-2-butene CT-absorbance is shifted to lower energy by more than 300 nm... 

Linewidths Figure 1 shows the variation with temperature of the l C-NMR spectrum of 1-butene adsorbed on NaGeX zeolite at a surface coverage of 0= 0.5 while Table II reports the linewidth (AH at half intensity) variations for gaseous, liquid and adsorbed 1-and trans 2-butene molecules. 

Phenylazide and 3-methyl-1-butene were dissolved in n-hexane and stirred for 20 days in the dark. Then, unreacted phenylazide and 3-methyl-1-butene were removed by distillation. A liquid residue with a higher boiling point was obtained. The electronic spectrum of the residue differs from both components. It gives absorption peaks at 287nm and 303nm as is shown in Figure 1. 

IR spectrum of the residue shows the disappearance of absorption peaks at 2150cm-1 and 1650cm- , 900cm-1 and 650cm- which are due to v(N=N=N) of the azido group, v(C=C) and 6(CH2) of 3-methy1-1-butene, respectively. In the mass spectrum, the parent peak due... 

The peaks in the m/z 50-57 range of the 1-butene El spectrum could be misinterpreted as a complex isotopic pattern if no formula were available on the plot (Fig. 3.8). However, there is no element having a comparable isotopic pattern and in addition, all elements exhibiting broad isotopic distributions have much higher mass. Instead, the 1-butene molecular ion undergoes H, H2 and multiple H2 losses. The m/z 57 peak, of course, results from In a similar fashion the peaks at m/z 39 and 41 appear to represent the isotopic distribution of iridium, but this is impossible due to the mass of iridium (cf. Appendix). However, these peaks originate from the formation of an allyl cation, CsHs, m/z 41, which fragments further by loss of H2 to form the CsHs" ion, m/z 39 (Chap. 6.2.4). 

Fig. 3.8. El mass spectrum of 1-butene. Adapted with permission. NIST, 2002.

NOESY spectrum of (E)-2-bromo-2-butene, (300 MHz in CDCI3 solution)... 

The proton NHR spectrum of the crude buten-l-ol was essentially identical to that of the distilled product, except for traces of solvent. This crude silylbuten-l-ol was of sufficient purity for the tetrahydropyridine synthesis described in the next procedure. 

Z,9Z)-3-Hexyl-5-methylindolizidine (17a) from a Solenopsis sp. exhibits characteristic peaks at miz 208 (M — CH3) and 138 (M - CgHjj, a base peak) as well as a parent peak at m/z 223 in the mass spectrum. The stereochemistry has been determined by synthesis. Racemic (5Z,9Z)-3-hexyl-5-methylindolizidine (17a) was prepared by the above-mentioned methodology, using octene-1-oxide instead of butene-1-oxide (Scheme 47) (134). 

The trapped product gave an immediate test with KI in acetic acid. Its infrared spectrum was similar to that of 3-butene-2-ol with major absorption peaks at 3, 8.7, 9.5, 10.3, and 10.8 microns and minor peaks at 6.3, 7.2, 7.7, 11.6, 12.4, and 12.6 microns. There was no absorption arising from carbonyl. In a 25% solution of hydroperoxide in carbon tetrachloride, the hydroperoxide proton gave rise to a broad band at 8.7 p.p.m. (referred to TMS) in the NMR spectra. 

These model studies permitted demonstration of metabolic a-hydroxylation of NPy by isolating 2-hydroxytetrahydrofuran as a metabolite of NPy. This was accoitplished by trapping 4-hydroxy-butyraldehyde as its 2,4-dinitrophenylhydrazone (DNP) derivative. For in vitvo studies, NPy-2,5-l C was incubated with rat liver microsomes, 02i and an NADPH generating system. After the incubation was complete, DNP reagent was added to the mixture and the products were extracted and examined by preparative TLC. A radioactive band corresponding to the DNP of 4-hydroxybutyralde-hyde was observed. This band was not present in controls in which NADPH was omitted or in which boiled enzyme was used. The mass spectrum was identical to that of a reference sairple. In addition, a minor metabolite with mass spectrum identical to that of the DNP of 2-butenal was also isolated. These results showed conclusively that NPy underwent metabolic a-hydroxylation in this in vitro system. 

---