3-Tyrosine acid, also known as L-DOPA, is the key to the treatment of Parkinson's disease. In Parkinson's disease, dopamine can cause death, resulting in less dopamine production, resulting in diseases such as shock, tremor, and myorectosis. 3-Tyrosine acid acts as a dopamine precursor, which can penetrate the blood barrier, reduce dopamine and dopamine deficiency by dopamine carboxylase, and improve the symptoms of Parkinson's disease.
It can effectively improve the ability of patients to perform well, and can greatly improve the life expectancy of patients. However, it is also not effective, and it is easy to have many side effects when used in large quantities during the period. Often, it is caused by the reaction of the digestive tract, such as heart attack and vomiting, due to the stimulation of peripheral dopamine. There are also side effects, such as depression, which is caused by involuntary stimulation of dopamine during the period, resulting in mental change. There are also many psychiatric disorders, such as hallucinations, delusions, depression, etc., or due to the wide effect of dopamine on the body, which affects many spiritual pathways.
Therefore, the use of 3-tyrosine in the bed requires a balance of advantages and disadvantages. According to the patient's condition, age, and tolerance, a plan of use is carefully formulated to maximize the effectiveness and minimize side effects, so as to maximize the benefit of the patient.

3-Hydroxybutyric acid is an endogenous substance in the human body that exists in normal physiological processes and has specific physical properties. It is described as follows:
Its appearance is usually colorless to light yellow liquid, which is viscous. Looking at its color, pure is clear and transparent, and there are no impurities or precipitation. This property is similar to many other liquid organic compounds, and can be clearly distinguished by the naked eye under normal light conditions.
When it comes to smell, 3-hydroxybutyric acid has a slightly weak and special smell, but it is not pungent or unpleasant. This smell is similar to that of general fatty acids and their derivatives, but its smell is very light, and it is difficult for ordinary people to detect if they do not deliberately get close and smell it.
3-hydroxybutyric acid is soluble in water due to the presence of a hydroxyl group (-OH) in the molecular structure, which can form hydrogen bonds with water molecules, thus enhancing its solubility in water. Not only that, it also has a certain solubility in some organic solvents such as ethanol and acetone. This property is derived from the principle of similarity compatibility. Because the molecule has both polar and non-polar parts, it can interact with a variety of organic solvents.
As for the boiling point, due to the presence of hydrogen bonds and other forces between molecules, its boiling point is relatively high. Specifically, at standard atmospheric pressure, it is about a certain temperature range. A higher boiling point means that more energy needs to be supplied to make it change from liquid to gaseous state. This property is of great significance when separating and purifying it. It can be separated from other substances with a large difference in boiling point by controlling the temperature.
In terms of melting point, 3-hydroxybutyric acid also has a specific value. When it is below the melting point temperature, it will condense from liquid to solid. The transition of this physical state is also influenced by intermolecular forces. The existence of the melting point makes it necessary to pay attention to the effects of its solid state properties such as loss of fluidity during storage and transportation if the ambient temperature is below the melting point.

3-Hydroxybutyric acid, its chemical properties are relatively stable.
This substance can generally maintain a stable state under normal temperature and pressure, as long as it does not come into contact with highly active chemical substances such as strong oxidants, strong acids, and strong bases. In its molecular structure, although the presence of hydroxyl and carboxyl groups gives it a certain reactivity, it is not easy to spontaneously produce significant chemical changes in the conventional environment.
However, if it is placed in a high temperature environment, the chemical bond vibration in the 3-hydroxybutyric acid molecule intensifies and the energy increases, which may trigger a dehydration reaction. The hydroxyl group in the molecule interacts with the carboxyl group, loses a molecule of water, and forms a lactone structure. If there is a suitable catalyst in the environment, it will also accelerate the process of such reactions.
If it encounters a specific alcohol, under the action of an acidic catalyst, the carboxyl group of 3-hydroxybutyric acid will be esterified with the hydroxyl group of the alcohol to form a corresponding ester compound. However, without a catalyst and suitable reaction conditions, this esterification reaction is difficult to occur naturally.
Looking at its situation in aqueous solution, 3-hydroxybutyric acid will ionize a small amount due to the weak acidity of the carboxyl group, generating hydrogen ions and corresponding acid ions, but the degree of ionization is extremely limited, and the solution as a whole can still maintain a relatively stable state.
In conclusion, under common and mild environmental conditions, the chemical properties of 3-hydroxybutyric acid are quite stable, but once the conditions change, contact with specific reactants, at special temperatures, or with catalyst intervention, the corresponding chemical reaction may occur.

To prepare ethyl tri-hydroxybutyrate, the methods are as follows:
First, the esterification reaction is carried out under heating conditions with hydroxybutyric acid and ethanol as materials, and concentrated sulfuric acid as catalyst. The text says: "Ethyl tri-hydroxybutyrate can be obtained by using hydroxybutyric acid and ethanol as raw materials, concentrated sulfuric acid as catalyst, and heating to esterify it." In this reaction, concentrated sulfuric acid has catalytic power and can promote the reaction to generate esters. However, it should be noted that after the reaction is completed, due to the corrosive nature of sulfuric acid, it needs to be properly handled, and this reaction is reversible. To increase the yield, the amount of a reactant can be increased, or the product can be removed in time.
Second, hydroxybutyric acid can be formed into acyl chloride first, and then reacted with ethanol. That is, hydroxybutyric acid interacts with thionyl chloride and other reagents to obtain hydroxybutyryl chloride, which then meets ethanol. The acid chloride has high activity and is easy to react with ethanol to form esters. As the ancient saying: "Shilling hydroxybutyric acid and thionyl chloride to obtain hydroxybutyryl chloride, and then interacting with ethanol, ethyl tri-hydroxybutyrate can be obtained." This approach can avoid the reversible drawbacks of esterification reaction and improve the yield. However, thionyl chloride is toxic and corrosive, and it must be operated in a well-ventilated place, and the equipment requirements are also high.
Third, the transesterification reaction can be used. Methyl hydroxybutyrate and ethanol are used as the starting materials, and ethyl tri-hydroxybutyrate is obtained by transesterification under the action of Take methyl hydroxybutyrate and ethanol, add a catalyst, and perform a transesterification reaction to obtain the target ester. "The conditions of this method may be milder, but the choice of catalyst and the regulation of reaction conditions are crucial to achieve optimal yield and purity.

Looking at the current market, the price of 3-hydroxybutyric acid fluctuates quite a lot due to many reasons. It may be used in various fields such as medicine and chemical industry, with different needs and different prices.
In the process of refining medicine, the purity of 3-hydroxybutyric acid required is extremely high, and the preparation is difficult, so its price is high. In the market, the price per gram of such high purity may reach tens of gold or even hundreds of gold. The reason is that medicine is related to human life, and the purity and impurities are strictly controlled. The preparation process is complicated, and it consumes huge manpower, material resources, and financial resources.
If used in chemical synthesis, the requirements are slightly lower, and the price is also reduced. Usually purchased in bulk, per kilogram or between hundreds of gold and thousands of gold. Chemical applications are wide and the dosage is large, but the purity requirements are not as severe as those of medicine, and the preparation cost is slightly lower, which is a reduction in price.
There are different sources, natural extractors, complicated processes, difficult to find raw materials, and high prices. For chemical synthesizers, although they can be mass-produced, the cost of upfront R & D investment and equipment purchase should not be underestimated, so their price is not low. And changes in market supply and demand also affect their price. If demand is strong and supply is small, the price will rise; if supply is sufficient and demand is weak, the price will fall.
In summary, the price of 3-hydroxybutyric acid in the market, high-purity pharmaceutical use, tens of gold to more than 100 gold per gram; chemical use, hundreds of gold to thousands of gold per kilogram spectrum, due to the use, purity, source, supply and demand and other factors intertwined, causing its price fluctuations.