The Research About Detection And Solubilization Increasing Of Vitamin A And The Biomimetic Synthesis Of Nitrogen Compounds

Vitamin A has the function of promoting the growth and maintaining skin integrity, bones and visual sense. It is widely used in the practice, and a lot of foods, medicines and health care products are supplemented with vitamin A. Due to its instability in the external environment, susceptible to light, oxygen, the detection of vitamin A in all kinds of products is still a challenge. The current detection technology is of low accuracy, repeatability and takes long time, so, looking for a simple, accurate and high reproducibility detection method has practical importance. In addition, vitamin A is fat-soluble and almost insoluble in water. This limits its application in water soluble products. Therefore, transforming fat-soluble vitamin A into water-soluble vitamin A also has important practical significance.The detection methods such as direct solvent dilution, solid phase SPE column elution, chloroform extraction and chloroform ultrasound were taken respectively to the content detection of vitamin A. The results showed that chloroform ultrasound method can accurately and efficiently detect the content of vitamin A in samples. Chromatographic conditions:the C18 alkyl bonding silica gel as the filling agent, methanol as mobile phase; flow velocity:1.0ml/min; detected wavelength:325nm; column temperature:30℃. The ultrasound treatment method of sample:weighing about 0.5g sample to a beaker, added 3g diatomite, mixing well, taking chloroform of 100ml into the beaker, recording the weight, then ultrasound for 40min, cover the weight loss. The test of this content detection method of vitamin A shows that this method is feasible.In this paper, the method of solubilization increasing of vitamin A was also studied. The physical dispersion technique, solid dispersion technique and the spray drying technology were adopted respectively. The results showed that the spray drying technology work well and the vitamin A powder obtained can dissolve fast in cold water.Hantzsch dihydropyridine esters, as a analogue of NADH, is a kind of cheap, readily available, non-toxic and widely used organoreductant in organic synthesis. Nitrogen compunds widely exist in food and drugs. The research shows that the imine reduction or direct reductive amination are the effective ways to abtain nirogen compounds with Hantzsch dihydropyridine esters as hydrogen source in the presence of Lewis acid or Bronsted acid, such as Sc(OTf)3, ZnCl2 or phosphoric acid derivatives. But, so far, catalyst acids are absolutely necessarily in these reactions. The catalyst-free reduction has not reported. In addition, for the preparation of chiral nitrogen compounds, the reported catalyst is limited to chiral phosphoric acid derivatives. Therefore, with Hantzsch dihydropyridine esters as hydrogen source, the study on catalyst-free imine reduction, reductive amination and preparation of new type of Brφnsted acid organocatalysts adapted to the reduction of imines seem to be important.In this article, Hantzsch dihydropyridine ester was used as hydrogen source to the reduction of aldimines. Under catalyst-free condition, the reduction of aldimines was realized. The optimal reaction condition was that the reaction was carried out in toluene with 1.1 equiv of Hantzsch esters for 24h at 70℃. Under this optimal condition, a series of aldimines were reduced and the yield was up to 99%. In the further study, catalyst-free reductive amination of aldehydes under microwave irradiation was studied with Hantzsch dihydropyridine ester as hydrogen source. The reaction conditions were optimized. The best result was obtained when the reaction was performed in chloroform with 1.2 equiv of Hantzsch esters for 30min at 55℃. The reduction of a series of aldimines was realized under this optimal condition, and the yield was up to 95%.Meanwhile, in this paper, a series of chiral urea derivatives were synthesized through the reaction of isothiocyanates, isocyanates and tert-butyl sulfonamide, cyclohexanediamine, biphenyl aminoethyl alcohol. These catalysts were used in the reduction of imines with the Hantzsch esters as the hydrogen source which the yield was up to 85%.