Glycols, reduction

In a preliminary chronoamperometry experiment Neto et al. observed higher Pt mass specific activities (A g V) for CH3OH oxidation at 0.5 V vs. RHE on PtSn(l l)/C compared to either PtRu or PtRuSn formulations. All catalysts were produced by the ethylene glycol reduction method [80]. 

The poor activity for methanol oxidation of PtRuSn was also reported for the eatalyst obtained by ethylene glycol reduction [80]. Contradictory results were presented regarding the effect of Mo. The addition of Mo to PtRu with 1 1 0.5 and 1 1 1 PtRuMo atomic ratios, coupled with thermal treatment at 673 K in Ha atmosphere, improved the methanol oxidation current density in linear voltammetry experiments, e.g., at 0.5 V vs. RHE the mass activity for PtRuMo (1 1 1) at 293 K was 1 A gpt" [121]. However, longer-term DMFC experiments were not presented. Many of these studies lack fundamental insights into the observed eleetrocatalytic effects... 

Impregnation, ethylene glycol reduction CNT/3.8-12%Pt H2PlCU.K2PtCL, 2-4 TEM, XPS O2 reduction in PEMFC 68... 

PtiRuiWi Ethylene glycol reduction Po2=0.2MPa [ElOH] = 1.0molL" T=90°C 38 [64]... 

N. Tomiya, K. Watanabe, J. Awaya, M. Kurono, S. Eujii, Modification of acyl-plasmin-streptokinase complex with polyethylene glycol reduction of sensitivity to neutralizing antibody. FEES Lett., 193 (1) 44-48. 

Dihydroxybutane. -butylene glycol, CH3CH(0H)CH2CH20H, b.p. 204°C. Manufactured by reduction of aldol or by the action of yeast on aldol. Used to prepare butadiene. Used in brake fluids, in gelling agents and as an intermediate in plasticizers. 

One of the main advantages of the stochastic dynamics methods is that dramatic tirn savings can he achieved, which enables much longer stimulations to he performed. Fc example, Widmalm and Pastor performed 1 ns molecular dynamics and stochastic dynamic simulations of an ethylene glycol molecule in aqueous solution of the solute and 259 vvatc jnolecules [Widmalm and Pastor 1992]. The molecular dynamics simulation require 300 hours whereas the stochastic dynamics simulation of the solute alone required ju 24 minutes. The dramatic reduction in time for the stochastic dynamics calculation is du not only to the very much smaller number of molecules present hut also to the fact the longer time steps can often he used in stochastic dynamics simulations. 

Tetraphenylethylene Glycol. This prcp iration illustnites the mild conditions under which aryl ketones may undergo bimolecular reduction to com-... 

This is an example of the reduction of an ester of a dibasic acid to the corre spending glycol (Bouveault-Blanc reduction) ... 

Note. Both tetramethylene glycol (1 4-butanediol) and hexamethylene glycol (1 6 hexaiiediol) may be prepared more conveniently by copper-chromium oxide reduction (Section VI,6) or, for small quantities, by reduction with lithium aluminium hydride (see Section VI,10). 

Acetone is reduced by amalgamated magnesium largely to a bimolecu lar reduction product, tetramethylethylene glycol or plnacol (CHjjjClOHjClOHjiCHj), some isopropyl alcohol is also formed ... 

Trimethylene dibromide (Section 111,35) is easily prepared from commercial trimethj lene glycol, whilst hexamethylene dibromide (1 O dibromohexane) is obtained by the red P - Br reaction upon the glycol 1 6-hexanediol is prepared by the reduction of diethyl adipate (sodium and alcohol lithium aluminium hydride or copper-chromium oxide and hydrogen under pressure). Penta-methylene dibromide (1 5-dibromopentane) is readily produced by the red P-Brj method from the commercially available 1 5 pentanediol or tetra-hydropyran (Section 111,37). Pentamethylene dibromide is also formed by the action of phosphorus pentabromide upon benzoyl piperidine (I) (from benzoyl chloride and piperidine) ... 

Regioselectivity of C—C double bond formation can also be achieved in the reductiv or oxidative elimination of two functional groups from adjacent carbon atoms. Well estab llshed methods in synthesis include the reductive cleavage of cyclic thionocarbonates derivec from glycols (E.J. Corey, 1968 C W. Hartmann, 1972), the reduction of epoxides with Zn/Nal or of dihalides with metals, organometallic compounds, or Nal/acetone (seep.lS6f), and the oxidative decarboxylation of 1,2-dicarboxylic acids (C.A. Grob, 1958 S. Masamune, 1966 R.A. Sheldon, 1972) or their r-butyl peresters (E.N. Cain, 1969). 

Citrate, C20 , cycIohexane-I,2-diaminetetraacetic acid, V,V-dihydroxyethyIgIycine, EDTA, F , glycol, hexametaphosphate, OH , P20 , triethanolamine Citrate, CN , C20 , 2,3-dimercaptopropanol, EDTA, F , NagP30io, oxidation to MnOy, P20 , reduction to Mn(II) with NH2OH HCI or hydrazine, sulfosalicylate, tartrate, triethanolamine, triphosphate, tiron... 

Butanediol. 1,4-Butanediol [110-63-4] tetramethylene glycol, 1,4-butylene glycol, was first prepared in 1890 by acid hydrolysis of N,]S3-dinitro-l,4-butanediamine (117). Other early preparations were by reduction of succinaldehyde (118) or succinic esters (119) and by saponification of the diacetate prepared from 1,4-dihalobutanes (120). Catalytic hydrogenation of butynediol, now the principal commercial route, was first described in 1910 (121). Other processes used for commercial manufacture are described in the section on Manufacture. Physical properties of butanediol are Hsted in Table 2. 

Manufacture. The manufacture of 1,4-cyclohexanedimethanol can be accompHshed by the catalytic reduction under pressure of dimethyl terephthalate ia a methanol solution (47,65). This glycol also may be prepared by the depolymerization and catalytic reduction of linear polyesters that have alkylene terephthalates as primary constituents. Poly(ethylene terephthalate) may be hydrogenated ia the presence of methanol under pressure and heat to give good yields of the glycol (see Polyesters) (66,67). 

Manufacture. Hydroxypivalyl hydroxypivalate may be produced by the esterification of hydroxypivaUc acid with neopentyl glycol or by the intermolecular oxidation—reduction (Tishchenko reaction) of hydroxypivaldehyde using an aluminum alkoxide catalyst (100,101). 

---