Diols large-scale

As early as 1904, 1,2-Propanediol Dinitrate was proposed (Ref 3) as an additive to lower the freezing temp of NG, but its practical application on a large scale was hindered by lack of the raw material, propane-1,2-diol. It is only recently that the synthesis of glycol from ethylene led to the development of a method for producing methyl glycol from propylene via cnioro-hydrin. Even so, propylene-1,2-glycol is somewhat more expensive than glycols derived from ethylene (Ref 9)... 

Preparation of the acetylenic dichloride by conversion of the diol in pyridine with neat thionyl chloride is difficult to control, and hazardous on a large scale. Use of dichloromethane as diluent and operation at —30°C renders the preparation reproducible and safer [1], During distillation at up to 110°C/7-8 mbar, slight overheating of the residue to 120°C caused explosive decomposition [2], Sensitive to detonator, sometimes to mechanical shock [3],... 

An application of industrial importance of Lewis acidic metal salts is the condensation of carboxylic diacids and diols to give polyesters. This is an acid catalysed reaction that in the laboratory is usually catalysed by protic acids. For this industrial application salts of manganese, nickel, or cobalt and the like are used. From a chemical point of view this chemistry may not be very exciting or complicated, the large scale on which it is being carried out makes it to an important industrial reaction [29],... 

Of equally high industrial potential as intermediate chemicals are the various HMF-derived products for which well-worked-out, large-scale adaptable production protocols are available. Of these, the 5-hydroxymethyl-furoic acid, the 2,5-dicar-boxylic acid, the 1,6-diamine, and the respective 1,6-diol (framed in Scheme 2.12) are the most versatile intermediate chemicals of high industrial potential, as they represent six-earbon monomers that could replace adipic acid, alkyldiols, or hexamethy-lenediamine in the production of polyamides and polyesters. 

The preceding chapter (7 ) described synthesis of model LC oligomeric diols and their incorporation into coatings binders of the baking enamel type. The enamels had far better hardness and impact resistance than control enamels made from amorphous or crystalline oligomeric diols. The model LC oligomers were synthesized by a Schotten-Bauman method that would be costly for large-scale production. 

A direct esterification procedure by which a linear polyester diol can be modified with p-hydroxybenzoic acid (PHBA) was demonstrated. The products are oligomers in which phenolic end-groups appear to predominate. They are heterogeneous and are probably liquid-crystalline when 30 wt% or more of PHBA is incorporated. The procedure has the advantage that appears adaptable to large scale production but the disadvantages that the polyols are predominately phenolic and are contaminated with small amounts of phenol and unreacted PHBA. 

Large-Scale Oxidations of Alcohols, Carbohydrates and Diols... 

This hydrogen-bond-driven large-scale structural organization has parallels in abiotic systems as well. For example, 1 1 mixtures of ra -l,2-diaminocyclohexane and C2 symmetric 1,2-diols self-assemble into well-defined supramolecular structures which have been characterized by X-ray diffraction analysis. The structures, some of which are stable to sublimation, are helical, the handedness of the helices being determined by the handedness of the 1,2-diamine [222]. 

Tetrahydrofuran is a commonly used solvent. It is a relatively stable ether and is miscible with both water and organic solvents. It is manufactured on a large scale by dehydration of butane-1,4-diol and catalytic reduction of furan. It is also obtained by base treatment of 4-haloalkan-l-ols and by acidic treatment of alk-3-en-l-ols and alk-4-en-l-ols. 

Kopropylidene D-erythronolactone <5) is commercially available, but it can easily be prepared by the method described on a large scale with an overall yield of 754 , whereby diol 4 need not he purified. 

Details for the large-scale synthesis of (R,R) 1,2-diphenyl-1,2-ethanediol by using the DHQD-CLB/NMO variation of catalytic AD have been published [47]. Under these conditions the crude diol is produced with 90% ee and upon crystallization, essentially enantiomerically pure diol is obtained in 75% yield. Subsequent improvements in the catalytic AD process now allow this dihydroxylation to be achieved with >99.8% ee (entry 20, Column 9) however, the Organic Synthesis procedure [47] is still an excellent choice for preparing large amounts of the... 

Sano, T. Ohashi, K. Oriyama, T. Remarkably fast acylation of alcohols with PhCOCl promoted by TMEDA. Synthesis 1999, 1141-1144. Carrigan, M. D. Freiberg, D. A. Smith, R. C. Zerth, H. M. Mohan, R. S. A simple and practical method for large-scale acetylation of alcohols and diols using Bi(OTf)3. Synthesis 2001, 2091-2094. 

Molybdenum complexes are the most effective catalysts known for the selective epoxidation of olefins with alkyl hydroperoxides (210-212). Commonly known is the Arco or Halcon process for the large-scale manufacture of propylene oxide from propylene. This process uses t-BuOOH or ethyl benzene hydroperoxide (EBHP) as an oxidant and Mo(CO)6, for example, as a source of Mo. The Mo(CO)6 acts as a catalyst precursor, which is converted into a soluble active form by complexation with diols (3). Chemists have designed several supported versions of the catalysts for this epoxidation chemistry. A clear classification can be made on the basis of the nature of the support. 

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