Erythritol, crystal structure

Erythritol tetranitrate (ETN) (Figure 1) is an explosive first prepared in 1849 [1] with similar properties to pentaerythritol tetranitrate (PETN). ETN is melt-castable, has impressive performance, and is not difficult to prepare, which increases the necessity for understanding its properties from a homemade explosive threat determination perspective [2]. Due to its handling sensitivity, ETN has been involved in recent accidents [3] and should not be handled outside of a dedicated explosives facility. We have recently reported the first X-ray crystal structure of ETN [4], and discussed the influence of crystal packing on the sensitivity of the material, relative to PETN [5]. Another recent publication also discusses basic characterization of ETN [6]. 

V. W. Manner, B. C. Tappan, B. L. Scott, D. N. Preston, G. W. Brown, Crystal Structure, Packing Analysis, and Structural-Sensitivity Correlations of Erythritol Tetranitrate, Cryst. Growth Des. 2014, 14, 6154-6160. 

Fig. 2.3. A questionable three-center bond from the neutron diffraction crystal structure analysis of erythritol [77]...

Ceccarelli C, Jeffrey GA, McMullan RK (1980) A neutron diffraction refinement of the crystal structure of erythritol at 22.6 K. Acta Cryst B36 3079-3083... 

The enzyme 2-C-methyl-D-erythritol-4-phosphate synthetase appears to catalyse a Bilik reaction (Figure 6.10) the substrate l-deoxyxylulose-5-phosphate is converted to the title compound via an intermediate aldehyde, whose carbonyl derives from C3 of the substrate. The first step is thus a Bilik reaction and the aldehyde is subsequently reduced by the enzyme using NADPH as reductant, The X-ray crystal structure of the Escherichia coli enzyme in complex with the promising antimalarial Fosmidomycin (a hydroxamic acid) reveals a bound Mn " coordinated to oxygens equivalent to the substrate carbonyl and 03. The stereochemistry and regiochemistry follow the normal Bilik course, although the crystallographers favour an alkyl shift rather than a reverse aldol-aldol mechanism. The intermediate aldehyde has been shown to be a catalytically competent intermediate. 

The electrochemical oxidation of polyhydric alcohols, viz. ethylene glycol, glycerol, meso-erythritol, xilitol, on a platinum electrode show high reactivity in alkaline solutions of KOH and K2C03 [53]. This electro-oxidation shows structural effects, Pt(lll) being the most active orientation. This results from different adsorption interactions of glycerol with the crystal planes [59]. 

C-methyl-D-erythritol 2,4-cyclodiphosphate synthase catalyses the conversion of 4-diphospho-cytidyl-2-C-methyl-D-erythritol 2-phosphate to 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MECDP) (Equation (7)). This reaction is part of the isoprenoid biosynthesis pathway in many plants and bacteria. The structure of the E. coli enzyme bound to Mn, cytosine monophosphate, and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate has been determined. The enzyme in the crystal and probably in solution is trimeric, three monomers are packed in a circular assembly with three-fold symmetry. The active site is at the interface of two adjacent monomers all the ligands bound to the Mn + come from one monomer and a MECDP molecule. The structure of this active site is shown in Figure 29 ... 

A similar species distribution is found for [(en)Pd(OH)2]/erythritol solutions, and a crystal stracture containing a binuclear complex analogous to 9 has been determined [19]. A solid-state structure of this type is also formed by ethylenediamine-copper(II) [20]. In strong alkaline aqueous solutions, the ethylenediamine-copper bond is cleaved and the formation of homolep-tic complexes such as the linear coordination polymer 10 (O Fig. 1) is enabled [21]. 

---