Hydroxyl value

Name Molecular formula Hydroxyl Value Acidity, % as acetic Carbonyl, wt % 0 Boiling range, °C Color, APHA Moisture, % Plash point, °C ... 

Fig. 2. Functional end groups and solution viscosity during polyester resin manufacture. Acid value is defined as the milligrams of KOH required to neutralize 1 g of polymer hydroxyl value is defined as the milligrams of acid equivalent required to neutralize 1 g of polymer. Solution viscosities are...

Formulations should be based on stoichiometric considerations. Based on a knowledge of the hydroxyl value of the polyol the amount of isocyanate necessary to cause chain growth should be calculated. The gas evolved will depend on the water content and additional isocyanate must be incorporated corresponding to the water present. When the isocyanate used equals the theoretical amount the system is said to have a TDI index of 100. In practice a slight excess of isocyanate is used (TDI index 105-110) to ensure complete... 

The increased durability obtained by siliconising a polyster resin comes from reacting a high hydroxyl value polyester with 20-30% of appropriate silicone resin. 

Hie extent of depolymerization of PET as a result of glycolysis requires the determination of die hydroxyl value of die glycolyzed PET ... 

The hydroxyl value (or hydroxyl number) method measures the number of -OH groups on a molecule. The result is reported in milligram of potassium hydroxide titrated by a sample of 1 g size thus it is a measure of both the chain length/molecular weight and purity of a... 

Results for the hydroxyl value determination were inconclusive the precision of the method and the normal range of results for receipts of EO were not significantly different. Combined with the finding of zero for the peroxide value, the oxidation hypothesis seems less likely. Moisture content and pH results were more interesting. Normally, pH readings on the ethoxylate were above 10. The moisture values were somewhat above typical values. These two results do not really support or refute the hypothesis of EO oxidation, but when solving a problem, any unusual or unexpected results are noteworthy. 

Precision The reproducibility of the method likewise must match the needs of the problem. The hydroxyl value method used in the Bulging Drum Problem might not have been precise enough to detect any differences between the good and bad EOs. 

Personnel Choosing an appropriate technique sometimes comes down to having the right person on your staff to perform the technique. If you, or no one in the lab, had had experience with the hydroxyl value titration, it might not have been an option in the Bulging Drum Problem. Certainly, if the operator of your triple quadrupole mass spectrometer is on vacation and there is no back-up operator, another method, or sending the samples to another lab, may be necessary. Should the method need to be transferred to another lab, does that lab have the requisite people for the job ... 

Estimation of alcohols and hydroxyl values by reaction with acetic anhydride (AA)... 

In a related assay, a hydroxyl value is determined for a fixed oil. A 1 3 mixture of AA in pyridine is used in the determination the pyridine is present as a catalyst. The hydroxyl value may be defined as ... 

To be completely accurate the acid value for the fixed oil should be added to the hydroxyl value since any free acid in the oil will titrate along with the excess reagents giving a small overestimate. The acid value for castor oil is about 2.0 giving a hydroxyl value for the above sample of 156. 

Reaction with acetic anhydride is used in pharmacopoeial assays of benzyl alcohol and dienestrol and determination of hydroxyl values of castor oil, cetosteryl alcohol and cetomacrogol. 

Oil % volatile (moisture) Hydroxyl value/mg of KOH g 1 Acid value/mg ofKOHg"1... 

Fig. 8. Zanamivir derivatives modified by replacement of the C-7 hydroxyl. Values in parentheses reflect the relative ability of the compounds to inhibit influenza A virus sialidase. The reference value for Zanamivir 1 is 1.0.

The hydroxyl value, methoxycarbonyl group content, acid value, melting point, content of diethylene glycol and of the obtained pre-condensates were determined in order to obtain more detailed information on the transesterification stage in the presence of the sodium salt of diethyl phosphite or di-sodium salt of 1,2-di-carbomethoxyethylphosphonic acid. 

Hydroxyl Value Determine as directed in Method II under Hydroxyl Value, Appendix VII. 

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