沉浸式翻译Final examination: synthesis of 1‑phenylthiourea
期末考试：1-苯硫脲的合成
Objective:
目的：
To apply in a laboratory experiment the academic knowledge of organic synthesis linked to carbonyl addition and substitution;
在实验室实验中应用与羰基加成和取代相关的有机合成的学术知识;
To learn common separation techniques in organic synthesis laboratories, such as the effect of pH on ionization status and solubility, recrystallization, and filtration;
学习有机合成实验室中常见的分离技术，例如pH值对电离状态和溶解度、重结晶和过滤的影响;
To understand the multistep synthesis concept.
了解多步合成概念。
The exam contents mainly include:
考试内容主要包括：
Intensive reading of the literature (J. Chem. Educ. 2021, 98, 986−990);
精读文献（J. Chem. Educ. 2021， 98， 986−990）;
Understanding of the mechanism involved in the synthesis of 1-phenylthiourea;
了解1-苯硫脲合成的机理;
Successful accomplishment of the synthesis and purification of 1-phenylthiourea;
成功完成1-苯硫脲的合成和纯化;
Investigation of the effect of the pH value on reaction work up and purification;
研究pH值对反应工作和纯化的影响;
Comprehensive discussion.
全面讨论。
Lab Session 1:
实验环节 1：
A two neck round bottom flask (50 ml) was charged with ammonium thiocyanate (MW = 76.1 g/mol, 1.1 equiv., 11.0 mmol, 837 mg), acetone (15 mL) and benzoyl chloride (MW = 140.6 g/mol, d = 1.21 g/l, 1 equiv., 10.0 mmol, 1.16 ml) with magnetic stirring at room temperature. The round bottom flask was then coupled to a condenser and transferred to an oil bath and heated at 60 ºC for 15 minutes. Then aniline (MW = 93.1 g/mol, d = 1.03 g/ml, 1 equiv., 10.0 mmol, 0.911 ml) solubilized in acetone (3 ml) was added dropwise and the heating of the solution was maintained for approximately 20 minutes. The reaction was monitored by TLC until aniline consumption. Following this, the reaction medium was poured into 50 ml of room temperature water and stirred vigorously and the precipitate formed was vacuum filtered and kept under reduced pressure. This intermediate is highly stable and can be stored for use in the next class.
在室温下磁力搅拌，将两颈圆底烧瓶（50 ml）装入硫氰酸铵（MW = 76.1 g/mol，1.1当量，11.0 mmol，837 mg），丙酮（15 mL）和苯甲酰氯（MW = 140.6 g/mol，d = 1.21 g/l，1当量，10.0 mmol，1.16 ml）。然后将圆底烧瓶连接到冷凝器中，并转移到油浴中并在60ºC下加热15分钟。然后滴加溶于丙酮（3ml）的苯胺（分子量=93.1g/mol，d = 1.03g/ml，1当量，10.0mmol，0.911ml），并保持溶液的加热约20分钟。通过TLC监测反应，直到苯胺消耗。之后，将反应介质倒入50ml室温水中并剧烈搅拌，对形成的沉淀进行真空过滤并保持减压。该中间体非常稳定，可以存储以备下一类使用。
Lab Session 2:
实验环节 2：
This class involves the preparation, isolation and purification of 1-phenylthiourea (11) through hydrolysis of intermediate 7 obtained in the lab session 1. Before proceeding, the students will be advised to save a small amount of the starting material for the purpose of TLC analysis.
本课程涉及通过水解在实验室会话 1 中获得的中间体 7 来制备、分离和纯化 1-苯硫脲 （11）。在继续之前，建议学生保存少量的起始材料，以便进行TLC分析。
In a round bottom flask (50 ml) fitted with a condenser, intermediate 7 (approximately 2.3 g, MW = 256.32 g/mol, 8.90 mmol) is added to a sodium hydroxide aqueous solution (2.5 M, 15 ml) and stirred at 90 ºC for approximately 20 minutes. The reaction flask is then cooled to room temperature. This reaction can be monitored using TLC by both neutralization with NH4Cl and micro extraction of the TLC sample with ethyl acetate. Upon reaction completion, the effect of the pH value on reaction work up and purification is evaluated. Students are needed to acidify the reaction medium to pH 2 using HCl and to pH 8 using saturated NH4Cl. The effect of this treatment is analyzed and discussed through TLC analysis of the precipitate formed. All the students must then adjust to pH 8 (by using Na2CO3). The filtrate is isolated by vacuum filtration and washed with water and cold ethanol. The base and acid addition can be performed using a Pasteur pipette and the pH checked with pH indicator strips. In general, only a few milliliters of acid or base are spent during this procedure.
在装有冷凝器的圆底烧瓶（50ml）中，将中间体7（约2.3g，MW=256.32g/mol，8.90mmol）加入到氢氧化钠水溶液（2.5M，15ml）中，并在90ºC下搅拌约20分钟。然后将反应瓶冷却至室温。该反应可以通过用 NH 4 Cl 中和和用乙酸乙酯微萃取 TLC 样品来监测。反应完成后，评估pH值对反应工作和纯化的影响。学生需要使用 HCl 将反应介质酸化至 pH 2，使用饱和 NH 4 Cl 酸化至 pH 8。通过对形成的沉淀物进行TLC分析来分析和讨论这种处理的效果。然后，所有学生必须调整到pH值为8（通过使用Na 2 CO 3 ）。滤液通过真空过滤分离，并用水和冷乙醇洗涤。可以使用巴斯德移液管进行碱和酸的添加，并用pH指示条检查pH值。一般来说，在这个过程中只消耗几毫升的酸或碱。