Micromole Of Acid Research Articles

Hydrogen-Catalyzed Acid Transformation for the Hydration of Alkenes and Epoxy Alkanes over Co-N Frustrated Lewis Pair Surfaces.

Hydrogen (H2) is widely used as a reductant for many hydrogenation reactions; however, it has not been recognized as a catalyst for the acid transformation of active sites on solid surface. Here, we report the H2-promoted hydration of alkenes (such as styrenes and cyclic alkenes) and epoxy alkanes over single-atom Co-dispersed nitrogen-doped carbon (Co-NC) via a transformation mechanism of acid-base sites. Specifically, the specific catalytic activity and selectivity of Co-NC are superior to those of classical solid acids (acidic zeolites and resins) per micromole of acid, whereas the hydration catalysis does not take place under a nitrogen atmosphere. Detailed investigations indicate that H2 can be heterolyzed on the Co-N bond to form Hδ--Co-N-Hδ+ and then be converted into OHδ--Co-N-Hδ+ accompanied by H2 generation via a H2O-mediated path, which significantly reduces the activation energy for hydration reactions. This work not only provides a novel catalytic method for hydration reactions but also removes the conceptual barriers between hydrogenation and acid catalysis.

Rates of production of individual volatile fatty acids in the rumen of lactating cows.

The rumen fermentation rates in individual lactating cows were measured in four different experiments. The results disclosed that the amounts and proportions of volatile acids formed could vary widely. In one case, a marked difference in the proportions of the acids produced arose within the experiment and correlated with a difference in the proportion of methane formed. The average rate of production per day was 10.5 moles butyric acid, 12.8 moles propionic acid, and 40 moles acetic acid. Manometric estimations of rate gave lower results than those obtained by the zero-time method, due to delay after sampling and to failure of the acids to liberate stoichiometric quantities of carbon dioxide. For those experiments in which zero-time rates were estimated, the average specific absorption rates, i.e., the amount absorbed per hour per micromole of acid in the rumen, were 0.37 for butyric acid, 0.38 for propionic acid, and 0.26 for acetic acid. The carbon dioxide, acids, and microbial cells produced in the rumen fermentation are estimated to account for about 90% of the carbon found in the milk and respiratory CO(2) of the cows. The carbon dioxide from the fermentation was about 27% of the carbon dioxide exhaled.

Rates of Production of Individual Volatile Fatty Acids in the Rumen of Lactating Cows1

The rumen fermentation rates in individual lactating cows were measured in four different experiments. The results disclosed that the amounts and proportions of volatile acids formed could vary widely. In one case, a marked difference in the proportions of the acids produced arose within the experiment and correlated with a difference in the proportion of methane formed. The average rate of production per day was 10.5 moles butyric acid, 12.8 moles propionic acid, and 40 moles acetic acid. Manometric estimations of rate gave lower results than those obtained by the zero-time method, due to delay after sampling and to failure of the acids to liberate stoichiometric quantities of carbon dioxide. For those experiments in which zero-time rates were estimated, the average specific absorption rates, i.e., the amount absorbed per hour per micromole of acid in the rumen, were 0.37 for butyric acid, 0.38 for propionic acid, and 0.26 for acetic acid. The carbon dioxide, acids, and microbial cells produced in the rumen fermentation are estimated to account for about 90% of the carbon found in the milk and respiratory CO(2) of the cows. The carbon dioxide from the fermentation was about 27% of the carbon dioxide exhaled.

IRRADIATION OF CHLOROFORM–WATER SYSTEMS WITH CO60 GAMMA-RAYS AND BETATRON X RAYS

The production of acid from two commercial brands of chloroform, on exposure to Co60 gamma-rays and high energy X rays from a betatron, has been measured. Inhibitor-free chloroform liberates acid in amounts varying linearly with the radiation dose. The specific yield, in micromoles of acid produced per liter of chloroform per kiloroentgen, varies inversely as the square root of the dose rate. The specific yields are slightly less for betatron radiations, compared with Co60 gamma-rays. The average lifetime of the free radical chains is about one second.