Guanidinium salts

Table 6.2 Sodium and guanidinium salt effects (relative reaction rates) of Diels-Alder reaction of anthracene-9-carbinol and N-ethylmaleimide...

Scheme 8.13 and Eqs. 8.6-8.10 reveal that lithiated methoxyallene 42 is sufficiently reactive towards a variety of electrophiles such as alkyl halides [44, 45], ethylene oxide [12c], tosylated aziridine 45 [46], dimethyl disulfide [12b], trialkylstannyl and trialkylsilyl chlorides [47, 48] and iodine [49]. These substitution reactions proceed with excellent regioselectivity and the corresponding a-functionalized products are obtained in good to high yields. An exceptional case was found by treatment of 42 with a guanidinium salt, which led to a 60 40 mixture of a- and y-adducts 50 and 51 (Eq. 8.11) [50],... 

AMINIUM/GUANIDINIUM SALT-BASED REAGENTS PROPERTIES AND THEIR USE... 

Two groups [451,452] have discussed the restricted rotation revealed by nuclear magnetic resonance in some penta-substituted guanidine bases, but which is not apparent [452] in the hexa-substituted guanidinium salts. Further work on the chromatography [453, 454] and mass spectra [455] of guanidines has appeared (see p. 129). 

Partially oxidized tetracyanoplatinates have attracted much attention in recent years because of their highly anisotropic physical properties.1 Although partially oxidized salts of K+, Na+, Rb and Mg+2 have been reported, the analogous bromide-deficient guanidinium salt is the only such compound containing an organic cation.2 A procedure for the preparation of this guanidinium salt has not been previously reported. 

The X-ray crystal structure determination of a number of simple guanidinium salts " (e.g., methylguanidinium dihydrogenphosphate) clearly demonstrates the existence of bidentate ionic hydrogen bonds as shown in Figure 10, with N(H)—0 contacts in the region of 2.9... 

The red solid remaining on the filter ia the so-called Mor-land g salt, or the guanidinium salt of the complex anion ... 

A summary of the transition temperatures of RNase in the presence of a variety of electrolytes is given in Table XX 361, 362). The effects of the usual salts follow the Hofmeister series. The remarkable difference in denaturing power of the various guanidinium salts is quite general. The sulfate actually tends to stabilize slightly while the thiocyanate is a more powerful denaturant than the chloride. Irreversible denaturation is markedly inhibited by spermine 363). There is no clear correlation between stabilizing effects and the complex inhibition curves obtained by Wold (see Section VI,E,2). 

Henry and Besser (Ref) report that the salt is less effective as a propint burning rate booster than the parent acid, although it still yields faster burning pro pints than similar formulations using Nitroguanidine. The cool proplnt formulation used as an evaluation vehicle consisted of NC (29.84), NG (7.86), l-ethyl-5-ethylamino-tetrazole (7.50), and the subject salt (54.80%) Ref R.A. Henry E.D. Besser, Preparation and Preliminary Evaluation of 1 -(5-Tetrazolyl)-2-Nitroguanidine and its Guanidinium Salt , NAVORD 3483 (1955)... 

Ref R.A. Henry E.D. Besser, Preparation and Preliminary Evaluation of l-(5-Tetrazolyl)-2-Nitroguanidine and its Guanidinium Salt , NAVORD 3483 (1955)... 

Iodoxybenzene (PI1IO2) has been briefly explored in the oxidation of benzylic alcohols to benzaldehydes, giving best results with an acetic acid catalysis.120 The guanidinium salt of m-iodoxybenzoic acid is soluble in CH2C12 and able to carry out oxidative breakages of 1,2-diols.120... 

Orthoamide 123 cleanly reduced mercuric acetate in ethanol at 25°C to mercury or mercurous acetate. The organic product formed is guanidinium salt 129 lX= OAc). Similarly, iodine in methanolic potassium carbonate at 25°C oxidized orthoamide 123 to guanidinium iodide 129 (X= I). On the other hand, orthoamide 122 does not react with mercuric acetate even in boiling ethanol. Syn-elimination of mercury and acetic acid from complex 130 must be slow but anti-elimination from complex 131 (Y= l or HgX2) must occur readily. 

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