METAL OXIDE ALKOXIDE POLYMERS: PART II. THE HYDROLYSIS OF TANTALUM PENTAETHOXIDE

1961 ◽  
Vol 39 (9) ◽  
pp. 1818-1826 ◽  
Author(s):  
D. C. Bradley ◽  
H. Holloway
Keyword(s):  
Metal Oxide ◽  
Tantalum Oxide ◽  
Structural Models ◽  
Degree Of Polymerization ◽  
Degree Of Hydrolysis ◽  
Oh Groups ◽  
Infrared Studies ◽  
Hydrolysis Of ◽  
Considerable Range ◽  
Characteristic Manner

The hydrolysis of tantalum pentaethoxide has been studied in boiling benzene and in boiling ethanol. Soluble tantalum oxide ethoxides were obtained over a considerable range of hydrolysis. Infrared studies suggest that Ta—OH groups are absent in these products. Ebulliometric studies have shown that the number-average degree of polymerization varies with the degree of hydrolysis in a characteristic manner and this has been quantitatively explained in terms of fundamental structural models based on octahedrally 6-co-ordinated tantalum.

METAL OXIDE ALKOXIDE POLYMERS: PART I. THE HYDROLYSIS OF SOME PRIMARY ALKOXIDES OF ZIRCONIUM

1961 ◽  
Vol 39 (7) ◽  
pp. 1434-1443 ◽  
Author(s):  
D. C. Bradley ◽  
D. G. Carter
Keyword(s):  
Metal Oxide ◽  
Zirconium Oxide ◽  
Structural Models ◽  
Degree Of Polymerization ◽  
Degree Of Hydrolysis ◽  
Zirconium Alkoxides ◽  
Hydrolysis Of

Ebulliometric studies have been made on the hydrolysis of some zirconium alkoxides, Zr(OR)4 where R = Et, Prn, Bui, and Bun. The variation of the degree of polymerization of the zirconium oxide alkoxides so produced was determined as a function of the degree of hydrolysis. The results are interpreted in terms of structural models based on octahedrally 6-co-ordinated zirconium.

METAL OXIDE ALKOXIDE POLYMERS: PART IV. THE HYDROLYSIS OF SOME TANTALUM ALKOXIDES

1962 ◽  
Vol 40 (1) ◽  
pp. 62-72 ◽  
Author(s):  
D. C. Bradley ◽  
H. Holloway
Keyword(s):  
Metal Oxide ◽  
Tantalum Oxide ◽  
Structural Models ◽  
Degree Of Hydrolysis ◽  
Important Data ◽  
Polymeric Nature ◽  
Hydrolysis Of

Ebulliometric studies on the hydrolysis of tantalum pentaalkoxides Ta(OR)5, where R = Me, Prn, Bun, and Bus, have furnished important data on the polymeric nature of tantalum oxide alkoxides. It is shown from the variation of number-average degrees of polymerization as a function of degree of hydrolysis that the polymers conform to certain structural models. The structural models involve 6-co-ordinated tantalum.

METAL OXIDE TRIALKYLSILYLOXIDE POLYMERS (POLYTRIALKYLSILOXANOMETALLOXANES): PART I. TITANIUM OXIDE TRIMETHYLSILYLOXIDE POLYMERS

1963 ◽  
Vol 41 (3) ◽  
pp. 629-635 ◽  
Author(s):  
D. C. Bradley ◽  
C. Prevedorou-Demas
Keyword(s):  
Molecular Weight ◽  
Metal Oxide ◽  
Titanium Oxide ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Degree Of Hydrolysis ◽  
Controlled Conditions

Tetrakis-(trimethylsilyloxy)-titanium Ti(OSiMe3)4 has been hydrolyzed under controlled conditions in dioxane. The initial products of hydrolysis undergo facile disproportionation, e.g. 3Ti2O(OSiMe3)6 → 4Ti(OSiMe3)4 + polymeric Ti2O3(OSiMe3)2. Molecular weight determinations were made on the titanium oxide trimethylsilyloxide polymers (polytrimethylsiloxanotitanoxanes) obtained by thermal disproportionation. Structures have been suggested for the polymers on the basis of the variation of number-average degree of polymerization with the degree of hydrolysis.

Structural aspects of the hydrolysis products of metal alkoxides and metal trialkylsilyloxides

1969 ◽  
Vol 47 (22) ◽  
pp. 4101-4111 ◽  
Author(s):  
J. W. Lorimer ◽  
D. E. G. Jones
Keyword(s):  
Metal Oxide ◽  
Complex Structure ◽  
Theoretical Models ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Degree Of Hydrolysis ◽  
Special Cases ◽  
Plausible Mechanism ◽  
Branched Chains ◽  
Structural Aspects

The average degree of polymerization [Formula: see text] depends on the average degree of hydrolysis [Formula: see text] as[Formula: see text] over a large range of [Formula: see text] for all metal oxide alkoxides and oxide trialkylsilyloxides that have been formed by hydrolysis and examined in solution. A number of general theoretical models are developed which permit quantitative interpretation of the parameters a and b. Mixtures of linear or branched chains in proportions governed wholly or partly by the degree of polymerization of the unhydrolyzed alkoxide can explain all the data on oxide alkoxides in solution in their corresponding alcohol, and the model leads to a plausible mechanism for disproportionation. Similar models with more complex structure can be involved in the metal oxide trialkylsilyloxides. Heterogeneity in the composition of the repeating units or in the number of metal–oxygen–metal bridges between successive repeating units can also be significant for both oxide alkoxides and oxide trialkylsilyloxides. Models involving cyclic chains are possible, but steric effects make them improbable in many cases. Mixtures of chains with equal average degrees of hydrolysis for each type of chain have been assumed in previous analyses, but are shown to be special cases of the more general model.

scholarly journals Hydrolysis of organometallic and metal–amide precursors: synthesis routes to oxo-bridged heterometallic complexes, metal-oxo clusters and metal oxide nanoparticles

2018 ◽  
Vol 47 (11) ◽  
pp. 3638-3662 ◽  
Author(s):  
J. A. Garden ◽  
S. D. Pike
Keyword(s):  
Metal Oxide ◽  
Metal Oxide Nanoparticles ◽  
Heterometallic Complexes ◽  
Oxide Nanoparticles ◽  
Oh Groups ◽  
Synthesis Routes ◽  
Hydrolysis Of ◽  
Metal Oxo Clusters

Organometallic and metal amide reagents react with –OH groups to generate metal–oxygen connectivity, yielding metal-oxo heterobimetallics, clusters and nanoparticles.

METAL OXIDE ALKOXIDE POLYMERS: PART III. THE HYDROLYSIS OF SECONDARY AND TERTIARY ALKOXIDES OF ZIRCONIUM

1962 ◽  
Vol 40 (1) ◽  
pp. 15-21 ◽  
Author(s):  
D. C. Bradley ◽  
D. G. Carter
Keyword(s):  
Metal Oxide ◽  
Structural Models ◽  
Zirconium Alkoxides ◽  
Hydrolysis Of

The hydrolysis of zirconium alkoxides with secondary or tertiary alkoxide groups Zr(OR)4, where R = Pri, Bus, Bul, and Amt, has been studied. The relatively low polymers formed by the metal oxide alkoxides have been interpreted on the basis of structural models involving octahedrally 6-co-ordinated zirconium.

Metal Oxide Trialkylsilyloxide Polymers. Part VI. Aluminum Oxide Trimethylsilyloxides

1971 ◽  
Vol 49 (13) ◽  
pp. 2310-2314 ◽  
Author(s):  
D. C. Bradley ◽  
J. W. Lorimer ◽  
C. Prevedorou-Demas
Keyword(s):  
Metal Oxide ◽  
Aluminum Oxide ◽  
Linear Dependence ◽  
Degree Of Polymerization ◽  
Oh Groups ◽  
Molecular Weights ◽  
Controlled Conditions ◽  
Adjacent Unit ◽  
Oxygen Atoms

Tris(trimethylsilyloxy)aluminum, [Al(OSiMe3)3]2, was hydrolyzed under controlled conditions in dioxane at 25 °C. The soluble initial products [AlOx(OH)z(OSiMe3)3−2x−z]n, with x = 0.03–0.65, underwent disproportionation when heated at 120–150 °C under vacuum to give final products with x = 0.8–1.1. Molecular weights were determined by cryoscopy in cyclohexane, and the linear dependence of 1/n on x was combined with an extension of the theory of regular polymer series to show that the number of OH groups, z, was small compared to the number of bridging oxygen atoms, x, per Al atom. The initial products consist of dimeric units, each linked to an adjacent unit by one or two oxygen bridges between aluminum atoms. The degree of polymerization is 1 to 4, based on the dimer unit. The final products have much higher degrees of polymerization (10–40, based on the dimer), and appear to contain a higher proportion of Al—O—Al bridges.

Polarographic study of hydrolysis of [8-lysine]vasopressin and its derivatives with blood serum of pregnant women

1980 ◽  
Vol 45 (4) ◽  
pp. 1099-1108 ◽  
Author(s):  
Mikuláš Chavko ◽  
Michal Bartík ◽  
Evžen Kasafírek
Keyword(s):  
Blood Serum ◽  
Pregnant Women ◽  
Degree Of Hydrolysis ◽  
Polarographic Study ◽  
Ph Optimum ◽  
Lysine Vasopressin ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Vasopressin Analogues

A polarographic study of the hydrolysis of [8-lysine]vasopressin and some hormonogens of the vasopressin series with the blood serum of women in the last week of pregnancy was studied. The dependence of hydrolysis on pH (pH optimum: 7.4-7.50, substrate concentration (Km 1.2 . 10-5M), pH stability and thermal stability were determined. The rate of hydrolysis of individual vasopressin analogues decreases in the order: [8-lysine]vasopressin > Nα-glycyl-prolyl[8-lysine]-vasopressin > Nα-leucyl-[8-lysine]vasopressin > Nα-alanyl-[8-lysine]vasopressin > Nα-phenyl alanyl-[8-lysine]vasopressin > Nα-diglycyl-[8-lysine]vasopressin > Nα-prolyl-[8-lysine]vasopressin > Nα-triglycyl-[8-lysine]vasopressin > Nα-sarcosyl-glycyl-[8-lysine]vasopressin. The degree of hydrolysis gradually increases to a multiple with the length of the pregnancy in consequence of the presence of oxytocine. However, vasopressin is also hydrolysed to a small extent with the enzymes from the blood sera of non-pregnant women. Under similar analytical conditions oxytocin was not hydrolysed with the sera of non-pregnant women and therefore oxytocin is a more suitable substrate than vasopressin for polarographic determination of serum oxytocinase.

Research on Enzymatic Hydrolysis of Whey Protein

2013 ◽  
Vol 411-414 ◽  
pp. 3205-3209
Author(s):  
Fang Qian ◽  
Lei Zhao ◽  
Shu Juan Jiang ◽  
Guang Qing Mu
Keyword(s):  
Enzymatic Hydrolysis ◽  
Whey Protein ◽  
Degree Of Hydrolysis ◽  
Quadratic Regression ◽  
Orthogonal Regression ◽  
Single Factor Analysis ◽  
Verification Test ◽  
Enzyme Dosage ◽  
Hydrolysis Conditions ◽  
Hydrolysis Of

Based on single factor analysis for the enzymatic hydrolysis of whey protein, papain was selected as the optimal enzyme and its enzymatic hydrolysis conditions were optimized by the quadratic regression orthogonal rotary test. The orthogonal regression model for degree of hydrolysis (DH) to three factors including temperature (X1), time (X2), enzyme dosage (X3) was established as follow: DH=10.40+0.22X1+0.30X2+1.31X3+0.019X1X2+0.011X1X3-0.039X2X3-0.39X12-0.16X22-0.40X32, Verification test showed a DH of 11.7% was obtained at the optimal hydrolysis condition of 56.6°C, 113.8 min and enzyme 8213.7 U /g protein, which basically consisted with the model theoretical value.

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