Sweet triangle system theory:甜味三角系统理论_留学生作业

Abstract摘要

糖类甜味与化合物结构的关系由夏伦伯格进行解释,并得到人们的认可,他提出带负电的相距0.25-4.0A(260-300nm)的原子A和B通过氢键相连.AH,B单元表示相邻碳原子上的两个羟基,其中的一个羟基拥有AH功能,B代表另一羟基的氧原子.他假设甜味的产生是因为供体甜味物质和受体之间有一对氢键,这对氢键是供体的AH,B系统和与受体蛋白上的AH,B系统结合形成的.
Relationship with the compound of carbohydrate sweetening explained by Shallenberge and recognized by the people he made away negatively charged 0.25-4.0A (260-300nm) of atoms A and B are connected by hydrogen bonds . AH, B represents relative units two hydroxyl groups on neighboring carbon atoms , wherein the AH has a hydroxyl functionality , an oxygen atom and B represents a hydroxyl group to another , he is assumed to produce because of the sweetness of a sweet substance hydrogen bond donor and acceptor , which the hydrogen donor is AH, B system , and in combination with AH, B system is formed on the receptor protein . AH, B system theoretical model shown in Figure 1-7. glucosyl saccharide group is required to produce the sweetness smallest group in the saccharide material a, B are the same as the same hydroxyl oxygen atom , two hydroxyl groups can be used as rough AH or B, and both can exchange their role in various other types of sweet flavor compounds (including amino acids ) can not be a swap roles . easily with the receptor protein as a sweet substance forming a hydrogen bond donor , since the peptide bond on the NH and carbonyl (C = O) as AH, B cells . the reason for all the sweet sweet compounds can rely on the hypothesis to explain this is AH-B system sweetness mechanism theory .

Kier[5]在AH,B系统理论的基础上,通过对1-烷氧-2-氨基-硝基苯的研究发现了另一个具有特性的基团,也就是AH,B以外的第三个基团X.他对AH,B系统理论进行了扩展,在很大程度上弥补了AH-B双氢键假说的不足,形成了著名的AH-B-X甜味三角理论.该理论指出X基团在与AH,B分别相距0.35 nm和0.55 nm的地方与二者构成AH-B-X甜味三角形(生甜作为亲脂性基团的X与AH,B这三个基团形成一个呈味的甜味三角形基团).

Kier [5] On the basis of AH, B systems theory, through on-1 - Alkyloxyl - Amino - nitrobenzene with features found another group , which is outside the AH, B third group X. he AH, B system theory has been extended to a large extent make up for the lack of AH-B dual hydrogen hypothesis , the formation of the famous AH-BX sweet triangle theory the theory states that X group with the AH, B , respectively 0.35 nm and 0.55 nm apart in both the local and the triangle constituting the AH-BX sweetness ( sweetening lipophilic group as X and AH, B three groups form a sweet taste triangle groups ) .

Theory to explain the causes of sweetness sweetness of sucralose甜味理论解释三氯蔗糖甜味成因

Sucralose is sucrose halides , since it was found that sucrose halides with sweetness and sweetness is much higher than sucrose , people sucrose halides produced a great deal of interest , due to the physical and chemical properties and safety of sucralose high , so people be studied and applied to enhance people's lives in a very important factor sweetness is lipophilic - hydrophilic balance that sweetness hydrophobic molecules with a hydrophobic membrane sweet taste receptor combination of parts , is easy to make the adsorbed molecules sweetness sweetness receptor membrane by introducing a suitable hydrophobic group in position X can effectively increase the hydrophobicity of the sugar molecules , thereby significantly enhancing the sweetness of sugar molecules with receptor protein force , greatly improving the sweetness.

Based on AH, B, X theoretical sweetness of the high intensity of the reasons for people to interpret sucralose , substituted C1 found proton receptive group O atom not high , representing 6% ~ 22% O atoms. sucralose and sucrose derivatives OH and C1 coexist in the molecule , and almost no sweet taste receptor C1 substituents form hydrogen bonds , so sucralose and its derivatives AH-B is the only part of the mother free hydroxyl group. sucralose has five OH groups , scientists Mathlouthi experimental analysis two authentication exists in the AH-B of sucralose , i.e., 3'-OH / 2-O 2-OH , and on this basis after / 3-O group were used as a sweetening triangle AH-B right, sweet receptor and they have two binding sites form a double hydrogen bond , resulting in a strong stimulation of sweetness because of its molecule C-1 ', C-4 and C-6 ' position of the chloro group is introduced , so that a triangle X sweetness lipophilic region becomes large , so that it is the membrane protein and the binding force of buds increased when the molecular sweetening group AH / B system when C-2 and C-3 ' hydroxyl and hydrogen bonding interactions occurring protein in the taste buds , it produced a greater and more lasting sweet stimuli , so the sweetness of sucralose is high [ 22 ] .

Currently permitted countries sucralose for use in food has been more than thirty , including the United States, where relatively broad range of applications in Japan , more than 400 kinds of foods are added using now many manufacturers of sucralose in China has registration, the total production of sucralose is about 150 tons , which is still far from meeting the needs of consumption , so our need to import sucralose, its price is about 2000 ~ 2500 yuan / kg. sucralose is far perfect sugar substitute, but the production process of the preparation of sucralose complex , and the threshold requirements are high technology content , a step often due to variations in a parameter will result in such small factors of the reaction failed so how to reduce their production costs , is a subject worthy of the great efforts of . sucralose as a sweetener in a new country has a strong market competitiveness , with some prospects. also give China has entered or about to enter the field of industrial product manufacturers to provide better opportunities. sucralose position in the food industry will be increasingly important in the long run , the production and application of sucralose in our country will have a significant social and economic benefits , will also promote China's high intensity sweeteners and raise the level of the food industry , to promote social progress and economic development.

Method of trityl protecting group called full five-step method and the method is the first method for the synthesis of sucralose , because the activity of various sugar hydroxyl groups are different , the size of the active 6,6 '> 4 > 1 ' > 4' > 2,3,3 ' method is the use of a trityl protecting group larger trityl protecting three primary hydroxyl groups of sucrose , after acetylation , detritylation reaction , then after acetyl migration , making sucrose 4,1 ', 6' free hydroxyl group while the other five positions are protected , and finally by chlorination, deacetylation to give the desired product sucralose.

Hough L. using triphenylmethyl chloride to react with hydroxyl groups to protect the three primary hydroxy ether , and then acetic anhydride to form an ester and reacting the hydroxy protecting the remaining five , then place in a solution of acetic acid and removal of trityl acetyl group transfer reaction of the resulting intermediate in pyridine solution at -75 ℃ by thionyl chloride and finally deacetylated synthesis of sucralose , the total yield of 14.6% . synthetic route shown in Figure 2-1 .

Jenner MR basis Houhg L. synthetic route on its transformation , and the detritylation reaction of acetyl groups migrated separately , and improved chlorination process , making it possible to greatly increase industrialization, the total yield up to 28.8%.

Tritylation purity sucralose synthesis intermediates and high, but the longer trityl reaction route , cycle time is longer, the complexity of the reaction conditions required to control many factors, and the use of part of the raw material triphenylchloromethane , pyridine is more expensive, resulting in high production costs , low cost industrial production , as a single group protection law is advantageous.

Single group Protection Act单基团保护法

Protection of one group is also called three-step method . Sucrose hydroxyl groups in the molecule is the most active activity 6 and 6 ' , but six hydroxyl groups play a crucial role in the sweetness of sucrose , so we should be considered first chlorinated sucrose 6 is not hydroxy chloride , chlorinated before we consider the first six protected hydroxy , and then use 4, l, 6 ' position of the three hydroxyl groups other than the hydroxyl-reactive activity , selective chlorination of three free hydroxyl groups , and then deprotected to obtain the final sucralose.

Depending on the esterification reagents , mono-ester synthesis routes are mainly the following methods , in 1982 Khan and Mufti first proposed single group protection law this route , then they choose the esterification reagent is acetic anhydride , and direct esterification , and then the esterification product of sucrose-6 - acetate selective chlorination , to facilitate isolation of the sucrose 6 - acetate , acetylated all its turn , then separated , and then sodium methoxide / methanol system deacetylation group to give sucralose, the total yield of 15.0% . the synthetic route shown in Figure 2-4 .

Conclusion结论

Neiditch protection 6 - Application of Metal hydroxy compounds are dibutyltin oxide , and it generates the sucrose 6 - benzoyl sucrose, and chlorination , etc. deacylation step of synthesizing sucralose synthesis of 6 - Benzoyl sucrose yield 94.4% , the effect is obvious form monoester ideal , but dibutyl tin oxide is expensive , if not effectively solve the problem of recovery of dibutyl tin oxide , and its future industrialization relatively slim . synthesis route shown in Figure 2-5.

Mentech J is the use of isopropyl azodicarboxylate Synthesis of 6 - benzoyl sucrose to sucrose 6 - protected, the reaction takes place under catalytic isopropyl azodicarboxylate , and then chlorination, prepared deacylation sucralose, the total yield of 21.5% , but a higher catalyst diisopropyl azodicarboxylate cool price, a larger amount, is not conducive to reducing the costs of the following synthetic route :

Stephen B. First, the acetylation of all the hydroxyl groups of sucrose in the resulting enzyme-catalyzed selective removal of the eight three acetyl acetyl sucrose to give the desired intermediate , acetyl sucrose yield to 36.0% intermediates This shows a high enzymatic selectivity, but the separation process using a silica gel column separation more difficult to industrialize. their synthetic route is shown in Figure 2-8.

Raffinose can be seen as sucrose galactose derivative , a trisaccharide molecule , the raffinose galactose residues located just on the sucrose 6-C , acts as the role of sucrose 6-C natural protective group , as long as by selective chlorination in - was removed under hydrolysis galactosidase galactose group, made the law less sucralose step , easy to operate, the yield was 18.2% , while the use of the reaction process . of - galactosidase can be obtained , and economy , in immobilized form, but sucralose can be selectively crystallized from the reaction solvent , so that the reaction and reduce the cost of recovery in the positive direction , but currently raffinose yet industrial production , which is separated from beet sugar molasses or cottonseed powder, natural sources , or through - galactosidase synthesis derived from galactose and sucrose , simply can not meet the industrial production of sucralose demand for raw sugar cottonseed synthetic route shown in Figure 2-9.Hough L. using triphenylmethyl chloride to react with hydroxyl groups to protect the three primary hydroxy ether , and then acetic anhydride to form an ester and reacting the hydroxy protecting the remaining five , then place in a solution of acetic acid and removal of trityl acetyl group transfer reaction of the resulting intermediate in pyridine solution at -75 ℃ by thionyl chloride and finally deacetylated synthesis of sucralose , the total yield of 14.6% . synthetic route shown in Figure 2-1 .

This paper is prepared to study for a single group of sucralose Protection Act and information on access to the extensive literature on the basis of : sucrose as raw material, trimethylorthoacetate as the acylating agent , p-toluenesulfonic acid as a catalyst in the Preparation of sucrose-6 under conditions - acetate using thionyl chloride and DMF as a reaction reagent preparation Vilsimier chlorinated agent, an important intermediate for preparation of sucralose-6 - ethyl acetate, to give the final sucralose deacylation , the papers single group protection sucralose synthesis reaction route.

The paper by a large number of orthogonal experiment to find the single step synthesis of a protecting group sucralose optimal reaction conditions for the separation and purification methods to find the intermediates and final products of reaction scheme is short , the high cost of synthesis cost , a broad market research value.