2-Butanol spectrum

In the butanol spectrum the most abundant fragment is at m/z = 31, corresponding to CH20H" , with a stmcture as shown H2C=OH" . The fragment lost was 74 — 31 =43, probably as a propyl radical, C3H7. This indicates that fragmentation between the first and second carbon atoms is favored as shown below. 

Three of the most intense peaks in the mass spectrum of ] 2 methyl 2 butanol appear at m/z 59 70 and 73 Explain the origin of these peaks J... 

The mass spectra of alcohols often completely lack a peak corresponding to the parent ion. This is due to extremely rapid loss of neutral fragments following initial ionization. For example, the mass spectrum of 2-methyl-2-butanol lacks a parent peak and contains strong peaks at M-15 (loss of CH3O and M-18 (loss of H2O). 

Preparation of 3-n-Butyiamino-4-Phenoxy-5-Suifamyibenzoic Acid To a suspension of 3-amino-4-phenoxv-5-sulfamylbenzoic acid (10 grams) in n-butanol (200 ml), concentrated sulfuric acid (2 ml) was added while stirring. The reaction mixture was heated under reflux under conditions in which the water formed during the reaction could be removed. IWhen, after dilution with n-butanol, the N MR-spectrum of a sample of the reaction mix-... 

Both fragmentation modes are apparent in the mass spectrum of 1-butanol (Figure 17.14). The peak at ni/z = 56 is due to loss of water from the molecular ion, and the peak at mjz = 31 is due to an alpha cleavage. 

Figure 17.14 Mass spectrum of 1-butanol (M+ = 74). Dehydration gives a peak at mjz - 56, and fragmentation by alpha cleavage gives a peak at m/z = 31.

Lewis and Johnson compared the c.d. spectra of amylose and cyclomaltohexaose, and showed that amylose is helical in aqueous solution. Cyclomaltohexaose is chromophorically equivalent to amylose, and it is known to assume a pseudohelix having zero pitch, and thus, no helical chirality. The conformation of amylose is clearly different from that of cyclomaltohexaose, as their c.d. spectra are very different (see Fig. 9). The difference in conformation was considered to be a matter of helical chirality. To confirm this, these workers measured the c.d. spectrum of an amylose-1-butanol complex presumed to have the V-form of helical conformation with the 1-butanol complexed in the channel of the helix. The c.d. spectrum of the complex is identical to that of amylose in aqueous solution. 

Spectrum 7.1 n-Butanol in CDCI3 with -OH obscured by multiplet at 1.39 ppm. 

Spectrum 7.2 n-Butanol in CDCI3 after shaking with two drops of D20... 

Beyond ethanol, the number of ft-alkanol dimer conformations becomes too large to be vibrationally resolved, even in supersonic jets. For -propanol, more than five isomers are discernible in the donor O—H stretching spectrum (see Fig. 8). For longer chains, there is a smaller number of dominant conformations [69]. Ar relaxation shows that the most stable -propanol and n-butanol dimers are those with the largest observed red shifts. For longer chains, the situation is more complex. However, the window of observed O—H stretching bands is quite independent of chain length beyond propanol. 

Biocatalysts able to use a large spectrum of substrates and/or to produce alcohols other than ethanol (butanol, in particular)... 

Fig. 6 Bottom-up (i) fluorescence excitation spectrum of the 1 1 diastereomeric complexes between (5)-2-naphthyl-l-ethanol (F ) and 2-butanol (M /M ) (ii) hole-burning spectrum obtained with the probe tuned on the transition located at - 136 cm ([F M ] complex) (iii) (c) hole-burning spectrum obtained with the probe tuned on the transition located at — 69 cm ([F -Ms] complex) (iv) hole-burning spectrum obtained with the probe tuned on the transition located at — 73 cm ([F -M/ ] complex). The probed band is denoted by A. The bands due to the bare chromophore are denoted by 2-NEtOH (reproduced by permission of the American Chemical Society).

Figure 7. NMR spectrum of

Figure 8. Upfield portion of the NMR spectrum of 2-phenyl-2-butanol (racemic) in benzene solution saturated with CSA (R>TFAE (220 MHz). 

Tamai and Masuhara [26] also worked on NOSH, but in 1-butanol. They could examine femtosecond dynamics for the C—O bond breaking and formation of a primary photo-product X, which formed within 1 psec and had a broad absorption with peaks at 450 and 700 nm. The spectrum of X then evolved, forming a broad merocyanine-type spectrum, which itself evolved with time to form the usual merocyanine spectrum in that solvent after less than 400 psec. The spectral broadening was said to be either due to the formation of a vibrationally hot ground state or to an equilibration between isomeric forms because the spectrum that formed at early times was similar to the spectrum usually obtained in cyclohexane. Tamai s spectra are shown in Fig. 3. 

The NMR spectrum of a mixture of 1-iodobutane and 1-butanol recorded at 298K in CDCI3 solution is given below. There is some overlap between the spectra of the components of the mixture. The TOCSY spectrum and the COSY spectrum are given on the facing page. Use the TOCSY and COSY spectra to determine the chemical shifts of all of the protons in 1-butanol and 1-iodobutane. 

The major ions in the spectrum are due to the loss of the neutral fragment water, as in the case of n-butanol 1,4 elimination is probably involved.The base peak is formed via homolytic cleavage next to the OH group followed by proton transfer (Fig. 9.13). The base peak of the mass spectrum is formed as shown in Figure 9.13. 

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