For methylamines

The original commercial source of E was extraction from bovine adrenal glands (5). This was replaced by a synthetic route for E and NE (Eig. 1) similar to the original pubHshed route of synthesis (6). Eriedel-Crafts acylation of catechol [120-80-9] with chloroacetyl chloride yields chloroacetocatechol [99-40-1]. Displacement of the chlorine by methylamine yields the methylamine derivative, adrenalone [99-45-6] which on catalytic reduction yields (+)-epinephrine [329-65-7]. Substitution of ammonia for methylamine in the sequence yields the amino derivative noradrenalone [499-61-6] which on reduction yields (+)-norepinephrine [138-65-8]. The racemic compounds were resolved with (+)-tartaric acid to give the physiologically active (—)-enantiomers. The commercial synthesis of E and related compounds has been reviewed (27). The synthetic route for L-3,4-dihydroxyphenylalanine [59-92-7] (l-DOPA) has been described (28). 

Figure 2.7. Expected temperature dependence (in the experimentally accessible temperature range) in regime IV in the context of Figure 2.5. Ground state tunnelling occurs in regime IV. The experimental data for methylamine dehydrogenase are apparendy linear in regime IV but, as noted in the text, this linearity will likely not extend to cryogenic temperatures.

Inspection of the table discloses that the permissible exposure level (PEL) = 10 ppm for methylamine. Since the... 

Although crystals have been reported for two amicyanins (Petratos et al., 1988b Lim et al., 1986), the type 1 blue protein, which is an electron acceptor for methylamine dehydrogenase (Tobari and Harada, 1981 van Houweligen et al., 1989), neither study has yet been completed. The structure of methylamine dehydrogenase from Thiobacillus versutus (not a copper protein) has recently been reported (Vellieux et al., 1989). The amicyanin from P. denitrificans has actually been cocrystallized with methylamine dehydrogenase (F. S. Mathews, personal communication. 

Hence the CN dissociation energy deduced for methylamine from Eq. (12.1), namely, Dcn = 92.00kcal/mol. Finally, Sanderson s approximation (12.14) leads to scn = 60.45 kcal/mol for this molecule. 

As seen from the data in Table 7-4 (abstracted from frequencies provided in Appendix A7) symmetric methyl group CH stretching frequencies change with substitution. The smallest value is for methylamine (chosen as the reference compound) and the largest is for methyl chloride. (Ethane has been excluded from this comparison as the symmetric stretch here involves all six hydrogens.)... 

Critical Properties. The critical temperature, pressure and volume for methylamine, nitrous oxide and their binary mixtures were experimentally determined and have been previously reported (34). The critical temperatures of the mixtures are intermediate between those of the pure components (Tc methylamine = 156.9°C Tc nitrous oxide = 36.5°C). The critical pressure goes through a maximum between the pure component values (Pc methylamine = 7.43 bar Pc nitrous oxide = 72.4 bar). The maximum (92.5 bar) is observed at about 46 wt.% methylamine content. The extraction conditions reported in the present study are all above the critical T and P of the fluids used. 

PhCD2NH2,40,42 as well as the temperature independence of the Ap/f, for CD3M f and (CD3)2NH2,52 Perrin and coworkers reinvestigated these and other secondary IEs.30,31 The amines studied were methylamine (16-do,1,2,3), benzylamine (18-d), N,A -dimethy 1 ani 1 ine (19-d3), 1-benzyl-4-methylpiperidine (20-d3), pyrrolizidine (21-d), N-methy 1 norborny 1 amine (22-d2), and A -benzyl-norbornylamine (23-d). The NMR titration method [Equation (19)], which gives highly accurate results, was applied to the reporter H depicted in boldface on the molecular structures. The results are presented in Table 5. According to those data the ApK for methylamine (16) is proportional to the number of deuteriums, and for 16-18, 22, and 23 the Apper D or the AAG° per D is nearly constant, 24 cal mol-1. 

Inductive effects can also influence the basic strength of neutral molecules (e.g. amines). The pKb for ammonia is 4.74, which compares with pKb values for methylamine, ethylamine, and propylamine of 3.36, 3.25 and 3.33 respectively. 

In the United States in 2001 the overall outlook for methylamines is very good. Production should remain strong as applications in the largest market segments are at or above the growth rates for GDP247. Raw material supplies of ammonia and methanol are abundant, but the price for natural gas has been... 

The United States has usually maintained a net export balance for alkylamines, but the trade surplus for methylamines has eroded since the mid-1980 s as a result of increasing imports of methylamines from Canada. Exports of methylamines reached a peak of 34 million pounds in 1993 and then fell to 8 million pounds in 2002 as overseas capacity has grown. The 1999 trade balance for methylamines is one of net imports116. 

Tresadern G, H Wang, PF Faulder, NA Burton, IH Hillier (2003) Extreme tunnelling in methylamine dehydrogenase revealed by hybrid QM/MM calculations potential energy surface profile for methylamine and ethanolamine substrates and kinetic isotope effect values. Mol. Phys. 101 (17) 2775-2784... 

One of the difficulties encountered when investigating or discussing rotation barriers about C-0 and especially C-N bonds is that this process may be overshadowed by a competitive process, namely inversion. Inversion barriers for simple amines are in the region of 5 kcal/mol [86], thus somewhat above the rotation barrier reported in Table 7 for methylamine. However, bulky substituents may markedly increase the rotation barrier and cause inversion to become the preferred process of conformational interconversion. This is precisely what happens with ferf-butylamines, where inversion (LXXVa-LXXVb interconversion) but not C-N bond rotation (LXXVa-LXXVc interconversion) is observed [87],... 

We have already reported our attempt to extend the theoretical treatment described in Sections 2—5 to the hydrazine molecule. As for the application of the treatment to experimental data, the situation is analogous to that described above for methylamine. 

Fig. 15. A comparison of experimental and simulated behavior for methylamine decomposition on Pt. (a) Temperature oscillations (b) predicted coverage oscillations of species a, CH3NH2, and b, a site blocker (c) simulated bifurcation diagram of temperature vs. current (d) experimental bifurcation diagram of temperature vs. current. (From Ref. 24.)...

Gibb et al. (1999) have reported shipboard measurements in the Arabian Sea confirming the emission of NH3 from these waters. These authors also measured methylamines in air and seawater and found that seawater concentrations of NH3 were 10-100 times greater than those of the methylamines, of which monomethylamine was the most abundant. They found that whilst inshore waters acted as sources and sinks for methylamines, offshore waters were a consistent sink. 

As seen in Table 14 gas phase protonation of cyclopropylamine is 0.9 kcal mol" more favorable than for methylamine but 4.4 kcal mol" less favorable than for isopropylamine. A possible explanation of the latter large difference is stabilization of cyclopropylamine by the conjugative interaction shown in Figure 3, Section III.D, and inductive destabilization of the cation by cyclopropyl. 

High airborne concentrations of methylamine can form, given its vapor pressure, with the potential for severe eye, nose, and respiratory tract irritation escape impairment and possible death. The immediately dangerous to life or health concentration for methylamine is 100 ppm. Anhydrous methylamine is a flammable gas, and aqueous methylamine is a flammable liquid. Vapors can travel a considerable distance to an ignition source and flash back because methylamine vapor density is heavier than air. 

Occupational exposure standards and guidelines for methylamine include the following ... 

Which solution would be more acidic a 0.10 M solution of aniline hydrochloride, C5H5NH3CI (K = 4.2 X 10 ° for aniline, CgHjNH2), or a 0.10 M solution of methyl-amine hydrochloride, CH3NH3CI = 5.0 X 10 for methylamine, CH3NH2) Justify your choice. 

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