The experience gained by the methyl glucosides makes it exceedingly probable that the simpler polyhydric alcohols also are suitable substances to employ in these syntheses; as a matter of fact, glycerol has been condensed with gallic acid.
Especially interesting appears the fact of plants utilising sugars for the esterification of acids, just as glycerol or monohydric alcohols may be employed for the same purpose.
No glycollic acid, oxalic acid, glycol, or glycerol was produced.
Of the three chief by-products of alcoholic fermentation, only glycerol remains at present referable directly to the sugar.
A small amount of glycerol is thus necessarily formed, as is actually found to be the case.
The white powder thus obtained is not completely soluble in water but is almost entirely dissolved by aqueous glycerol (2ยท5 to 20 per cent.
The lipase of castor oil seeds, a glycerol extract of the intestinal mucous membrane of the rabbit and pig, and an aqueous extract of bran have a slow hydrolytic action, whereas pepsin and trypsin are without effect.
On some of Pasteur's results, notably the very important one of the cultivation of yeast in a synthetic medium, he casts grave doubt, whilst he explains the production of glycerol and succinic acid as due to independent reactions.
The function of the glycerol is not understood but is probably that of lessening the rate of destruction of the yeast enzymes.
A small portion of this is converted by a reaction which may be variously interpreted as a Cannizzaro transformation or a reductase reaction into glycerol and pyruvic acid.
Since early work indicated the need for adding glycerol to diluted semen in order to protect the sperm during freezing, it was considered important to determine the levels of glycerol that sperm would tolerate at 5 deg.
Xylose was less effective, but its addition resulted in slightly better sperm survival than glycerol alone.
These investigators also gave a good account of their work at the British National Institute of Medical Research in London, where in 1949 they demonstrated that glycerol would protect fowl sperm so that it would survive freezing.
Effect of Sperm Numbers and Glycerol Level in Final Mixture on Freezability of Bull Sperm at -79 deg.
Portions of each diluted sample were tested at these stages of the procedure with glycerol alone added and with glycerol and various sugars added.
The most noticeable effect of the increase in glycerol level was the reduction in the rate of forward motion of the sperm.
While survival was fair over a short period of time with 19 percent glycerol at -20 deg.
These effects are discussed in the section on glycerol additions beginning on page 17.
I] The control differed from the 0-glycerol treatment in that no additional citrate or glycerol solution was added.
K] Glycerollevel in the final frozen mixture was 7 percent.
In other attempts at addingglycerol in order to freeze semen, the final proportion of yolk was diminished and better sperm survival was obtained.
M] Glycerollevel in the final frozen mixture was 7 percent.
A wax obtained from Rhus succedanea was shown by Stahmer to contain palmitic acid and glycerol in the form ofglycerol palmitate.
The percentage of glycerol obtained above includes any oxidizable impurities present after the purification.
At the present time the prices of glycerol and caustic potash are abnormally high, but the committee has considered that the methods adopted are for normal times and normal prices.
Determine the apparent percentage of glycerol in the sample by the acetin process as described.
Determination of the Glycerol Value of the Acetylizable Impurities.
From the N/1 NaOH consumed calculate the percentage of glycerol (including acetylizable impurities) after making the correction for the blank test described below.
Caustic soda cannot be substituted for caustic potash in the glycerol method.
This theory has been definitely disproved and it is now known that fats enter the blood only after a chemical splitting into glycerol and fatty acids, the latter being, to a large extent, combined with alkalies in the form of soaps.
A littleglycerol is present in the volatile matter.
Glycerol possesses all the characteristic properties of an alcohol, forming alcoholates with alkalies, esters with acids, etc.
Fats can be artificially synthetized by heating mixtures of glycerol and fatty acids, under considerable pressure, for some time at temperatures of 200 deg.
Glycerol This process, since it yields soap as one of its products, is called "saponification.
Fourth, that the sugar produced by the oxidation of fats is derived either from the glycerol or from the fatty acids of the fat, depending upon the nature of the latter.
When glycerol is heated with dehydrating agents, it is easily converted into acrolein, an unsaturated aldehyde having a peculiar characteristic pungent odor.
Most natural fats are mixtures of several different triglycerides in each of which the three (OH) groups of the glycerol has been replaced by the same organic acid radical, as in the example of stearin shown above.
Compounds of all of these types have been produced by combinations of glycerol with varying proportions of organic acids under carefully controlled conditions; and all of them found to possess fat-like properties.
In these, various sugars replace part or all of the glycerol as the alcoholic part of the ester.
Laurin (Trilaurin) may be prepared synthetically from glycerol and lauric acid.
Schutzenberger in 1876 showed that when castor seeds are steeped in water, fatty acids and glycerol are liberated, and attributed this to the hydrolytic action of an enzyme present in the seeds.
The formula for the calculation of the percentage of glycerol then becomes:-- {0.
N/1 caustic alkali for its saponification, so that the percentage ofglycerol may be calculated from the following formula:-- 35.
This is then saponified with a known volume of standard alkali, the excess of which is titrated with acid, and the percentage of glycerol calculated from the amount of alkali absorbed.
Hence, the acetin formed from the glycerol present in 1.
This consists in converting the glycerol into its ester with acetic acid, the acetic triglyceride, or triacetin being formed.
The estimation of actual glycerol in this is necessarily a matter of considerable importance, and a very large number of processes, which are constantly being added to, have been suggested for the purpose.
Enzyme B attacks this residue and splits off the remaining fatty acid group from it, enzyme C liberates only the choline from lecithin, and enzyme D opens lecithin at the ester bond between glycerol and phosphoric acid.
An empty catch-flask should be connected between the generator and the absorption flask in case any glycerol tends to suck back at the start of the reaction.
In a number of experiments, the glycerol used contained an appreciable amount of water.
The previous work, described in the literature, indicated that the best yields were obtained by the treatment of glycerol containing 1-2 per cent of acetic acid as a catalyst by gaseous hydrogen chloride.
Of the above methods, the only ones which need be considered are those in which a mixture of aniline, glycerol and sulfuric acid is heated with an oxidizing agent.
Pelouse, he says, "when glycerol is poured into a mixture of sulphuric acid of a specific gravity of 1.
It is thus obvious that picric acid is much less explosive than the nitric ethers, such as nitro-glycerol and nitro-cellulose, and very considerably less explosive than the nitrogen compounds and fulminates.
Nitro-glycerol, or glycerol tri-nitrate, was discovered by Sobrero in the year 1847.
By agitating glycerol with chloroform, fatty acids, rosin oil, and some other impurities are dissolved, while certain others form a turbid layer between the chloroform and the supernatant liquid.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "glycerol" in a variety of sentences. We hope that you will now be able to make sentences using this word.
