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  • 常规

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  • 埃斯特

    Ancient perfume flask shaped like a bird, dating from 580-550 B.C.

    An ancient perfume flask dating from around 580-550 B.C.
    ::一个古老的香水瓶子 来源于公元前580 -550年左右

    What is that smell?
    ::这是什么味道?

    Perfumes contain ingredients from a number of sources. Musk is obtained from animals, but the vast majority of perfume components are obtained from plants. Approximately 2,000 plant species have been used as sources for perfume materials. The needed chemicals are extracted using solvent extraction or distillation . The oils are diluted with ethanol to varying degrees, depending on the price of the finished product – the less ethanol present (meaning there is a higher percentage of the active odor ingredients), the more expensive the perfume.
    ::泡沫含有来自多种来源的成分。 Musk是从动物那里获得的,但绝大多数香水成分都是从植物那里获得的。 大约2 000种植物已经被用作香水材料的来源。 需要的化学剂是通过溶剂提取或蒸馏而提取的。 石油在不同程度上被乙醇稀释,这取决于成品的价格 — — 现有的乙醇越少(这意味着活性香味成分的比例越高 ) , 香水价格越高。

    Esters
    ::埃斯特

    An ester is an organic compound that is a derivative of a carboxylic acid in which the hydrogen of the hydroxyl group has been replaced with an alkyl group . The structure is the product of a carboxylic acid (the R-portion) and an (the R’-portion). The general formula for an ester is shown below.
    ::酯是一种有机化合物,是一种箱状酸的衍生物,其中氢氧化物组的氢被一个烷基化合物组所取代,其结构是箱式酸(R-portion)和(R-portion)的产物。一个酯的一般公式如下所示。

    General formula for an ester, illustrating its structure with alkyl and carboxylic acid portions.

    The R group can either be a hydrogen atom or a carbon chain. The R’ group must be a carbon chain since a hydrogen atom would make the molecule a carboxylic acid. The steps for naming esters along with two examples are shown below.
    ::R组可以是氢原子,也可以是碳链。 R组必须是一个碳链,因为氢原子将使分子成为碳酸。 命名酯的步骤和两个例子见下文。

    1. Identify and name the alkyl group (R’) that has replaced the hydrogen of the hydroxyl group. This is the first part of the ester name.
      ::确定并命名取代了氢氧基组氢的烷基组(R),这是酯名的第一部分。
    2. Name the carboxylic acid portion of the molecule (R-COO), but change the ending of the name from –oic acid to –oate . This is the second part of the ester name.
      ::点名分子中的箱状酸部分( R- COO ) , 但将名称的结尾从 - ocic 酸改为 - oate 。 这是 ester 名称的第二部分 。
    3. Leave a space between the alkyl group name and the name of the carboxylic acid derivative.
      ::在alkyl组名称与箱式酸衍生物名称之间留出一个空格。

    Chemical structure depicting the formation of esters and their components.

    Esters have lower boiling points than the from which they were derived because they cannot form with each other. This is because there are no hydrogen atoms bonded to oxygen atoms, as in the acid. Esters with shorter carbon chains are soluble in water, while those with longer chains are less soluble.
    ::碳链较短的埃斯特斯(Esters)的沸点比它们从中得出的沸点要低,因为它们无法相互形成。 这是因为没有氢原子与氧原子(如酸类 ) 。 碳链较短的埃斯特斯(Estes)在水中可以溶解,而链较长的埃斯特斯(Estes)则不易溶解。

    Esters are very commonly found in plants and are responsible for many distinctive odors and flavors. For example, methyl salicylate has the odor and flavor of oil of wintergreen, while propyl ethanoate has that of a pear.
    ::埃斯特斯(Esters)在植物中非常常见,并造成许多独特的气味和口味。 比如,甲基硅酸盐有冬季绿色油的气味和口味,而丙基乙酸盐则有梨的气味和口味。

    Wintergreen berries and a green pear, representing ester sources and flavors.

    Ester examples.
    ::Ester 实例。

     

     

     

    Review
    ::回顾

    1. What two types of molecules form  an ester?
      ::哪种两种分子形成酯?
    2. Do esters boil at lower or higher temperatures than the carboxylic acids they came from?
      ::消毒剂是否以低于或高于其原生的 箱状酸的温度沸腾?
    3. What does propyl ethanoate smell like?
      ::丙基乙酸乙酸酯的味道是什么?