羧基

Then Doripenem came into the market in the July ,2005. We studied the synthesis of Doripemen.Firstly, we synthesized the chemical 2 from the starting material------o-hydroxylphenylacylamine through Reformastky reaction, alkylation, Diekmann reaction, enolization, esterification and etc. Secondly, we synthesized the chemical 3 from L — hydroxylproline through the protection of carboxyl, amidogen and hydroxyl group, reduction by NaBr, SN_2 substitution and Mitsumobu reaction.

我们以水杨酰胺为起始原料，经Reformatsky反应、烷基化、Diekmann环合、烯醇化、酯化等反应合成双环母核2；再从L-羟基脯氨酸出发，经酯化保护羧基、保护氨基、保护羟基、硼氢化还原酯得醇、Sn2取代和Mitsumobu反应等合成巯基侧链3；最后由化合物3经脱保护、水解得硫醇，和化合物2在二异丙基乙基胺的作用下缩合，最后Pd／C催化脱保护，历经16步反应最终得到产物多尼培南。

The 4-acetylenyl phenylformic acid synthesized with the method contains carboxyl and terminal alkynyl, and is a valuable synthesized used in organic chemistry and is of great prospect to be applied in biomedicine, medicine field, etc, particularly in replacing phenylacetylene which is recently widely used in the synthesis of aromatic heterocycle, such as triazole.

本发明方法合成的4-乙炔基苯甲酸结构中含有羧基和末端炔基，是有机化学中极有价值的合成"砌块"，在生物医学、医药等领域有着十分重要应用前景，特别是取代苯乙炔近年来被广泛用于三唑等芳香性杂环的合成。

The active site of His and VI are both imidazole group, but His also has reactive amido and -COOH with negative charge.

前两种配基中的主要活性位均是咪唑基团，但组氨酸分子中还含有负电性的羧基和具反应活性的胺基。

The results of experiments show that the random chain scission of maleated PHB obeys the six-membered ring ester decomposition process.

结果表明，PHB-g-MA的热分解机理与PHB相同：在高温条件下，PHB分子链的酯基部分形成六元环结构，断链时夺取亚甲基氢，生成羧基和双键两种端基。

Result Under the pretreatment conditions, the content of acetone extractives transformed. The hydroxyl and carboxyl, belonging to auxochromic groups, were oxidized into the carbonyl and ester groups. Also, there were plenty of auxochromic groups and chromophoric groups in the acetone extractives of silver chain.

结果］刺槐在预处理条件下，丙酮抽出物成分发生了变化，羟基、羧基等助色基团在预处理条件下氧化成羰基、酯基等发色基团，且丙酮抽出物的主要成分中含有大量发色基团和助色基团。

The hydroxyl and carboxyl, belonging to auxochromic groups, were oxidized into the carbonyl and ester groups, belonging to chromophoric groups, during inducing discoloration under the pretreatment conditions, which makes the wood color deeper. There were plenty of auxochromic groups and chromophoric groups in the acetone extractives of silver chain. The interaction between the auxochromic groups and the chromophoric groups made the wood color deeper.

结论］羟基、羧基等助色基团在预处理条件下氧化成羰基、酯基等发色基团，使木材的颜色加深；刺槐木材丙酮抽出物的主要成分中含有大量发色基团和助色基团，这些基团间的相互作用使木材颜色加深。

Thiol groups were good to be used in functionalizing gold nanoparticles, and ester bond formation and breakage played the major role in this research. Thioctic acid and 11-mercapto-1-undecanol were used to functionalize the gold nanoparticles and form ester bond by using the carboxylic acid group on thioctic acid and the hydroxyl group on 11-mercapto-1-undecanol. Concentrated sulfuric acid was used to be the catalyst in this reaction, and sodium hydroxide was added for the proceeding of the reverse reaction.

硫醇官能基在金奈米粒子的修饰有很好的效果，利用带有硫醇官能基之tioctic acid 与11-mercapto-1-undecanol (11-MUDO)分子修饰在金奈米粒子上，并使TA上之羧基和11-MUDO上之羟基脱水生成酯化键，浓硫酸则是反应中的催化剂，而氢氧化钠则可促使系统进行逆反应。

The pathway The first committed step in Fatty acid biosynthesis is the carboxylation of acetyl CoA to form malonyl CoA which is catalyzed by the biotin-containing enzyme acetyl CoA carboxylase.

途 径 脂肪酸合成的第一个关键步骤是乙酰-COA 羧基化形成丙二酰单酰 COA ，这一步是在含生物素的酶乙酰-COA 羧化酶的催化下进行的。

"Fatty acids are carboxylic acids with a long hydrocarbon chain, usually straight, as the fourth substituent group on the carboxyl group that makes the molecule an acid."

脂肪酸一般由一条偶数碳原子的直链组成，整个长链上及其一端都有氢原子，另一端有一个羧基，所以是一种羧酸。

Six carboxyl acids DEMB was produced with Michael Reaction using triethylamine as alkaline catalyst and solvent, malonic acid and itaconic acid as raw materials.

以三乙胺为催化剂和溶剂，衣康酸和丙二酸为原料，采用迈克尔加成反应合成了含有6个羧基的多元羧酸DEMB。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。