Tag Archives: LinkedIn

Upcoming Crystallization Conferences and Events

There are several interesting upcoming crystallization conferences and meetings. Continue reading

What is Happening in Crystallization

Here is what is happening in crystallization: Continue reading

过饱和度:晶体成核与增长的驱动力

这是结晶专题系列的第三个博贴。如果您还没有看此系列的第一和第二个博贴,可以在此找到它们: 结晶与沉淀介绍降低溶解度与驱动结晶过程的常用方法

过饱和度是液体析出结晶工艺过程的驱动力。 结晶科研人员们通过把结晶过程中的过饱和度控制在有效程度来获得对结晶工艺过程的控制。

过饱和度:在指定温度下溶液中溶质的实际浓度与其溶解度之间的差值定义为溶液的过饱和度。

下图示意出溶液过饱和度的概念,同时介绍亚稳态区宽度(MSZW)- 既出现初始结晶的动力学边缘。

过饱和度很关键,因为它是晶体成核与增长的驱动力。成核是新晶体产生的过程,或从溶液中自发生成(初级成核)或来自体系中已有晶体(间接成核)。晶体增长是指晶体的大小随溶液中的溶质进入晶格而增加的过程。这些通常相互竞争的机理过程会决定最终晶体大小的分布 ― 一个重要的产品属性。过饱和度与成核和增长之间的关系可由以下(简化了的)公式来定义:

G = 增长速率

kg = 增长常数

g = 增长级数

B = 成核速率

kb = 成核常数

b = 成核级数

ΔC = 过饱和度

对于有机化合物的结晶体系,增长级数的数值一般在1 与2 之间, 成核级数一般在5与10之间。当我们将理论曲线作图,便可以清楚地看到为什么控制过饱和度如此重要。在低过饱和条件下,晶体增长比成核速率快,导致较大的晶体颗粒分布。而在较高的过饱和度条件下,晶体成核与增长相比占主导,最终导致较小的晶体颗粒。这一图解将过饱和度与成核速率、增长速率、和晶体大小相关联,清楚地显示出在需要生成指定晶粒大小或分布指标时对过饱和度的控制是如何至关重要。

了解了晶粒大小如何取决于过饱和度,在本系列的下一个博贴里我们来看为什么晶粒大小很重要。与此同时,结晶珍宝图再一次显示出理解溶解度、亚稳态区宽度、尤其是过饱和度的重要性。

要获得更正式一些的信息,以下书籍是很好的起点:

 

如果您有兴趣与其他结晶工作者或爱好者讨论,考虑加入已有600多成员的LinkedIn结晶社团

Supersaturation: Driving Force For Crystal Nucleation & Growth

This is the third blog post in a series dedicated to crystallization.  In case you missed the first and second in the series, they are available here: Introduction to Crystallization and Precipitation and Common Ways to Reduce Solubility and Drive Crystallization.

Supersaturation is the driving force for all solution crystallization processes. Crystallization scientists gain control over crystallization process and product quality by carefully controlling the prevailing level of supersaturation during the process. Continue reading

Safe Scale-up of a Grignard Reaction – LinkedIn OPRD Group

Recently, I saw a conversation on the LinkedIn Organic Process Research & Development (OPRD) Group that began with the subject:  “Precaution during scale-up of a Grignard reaction?”.  This discussion regarding the safety of Grignard reactions on scale made me realize how useful old chemical reactions can be, although not necessarily well-understood or controlled. Continue reading

Calibration Free Supersaturation Assessment and Control for the Development and Optimization of Crystallization Processes On-Demand Webinar

In case you missed the live webinar, Calibration Free Supersaturation Assessment and Control for the Development and Optimization of Crystallization Processes, presented today by Mark Barrett, Ph.D., Senior Research and Development Engineer, Solid State Pharmaceutical Cluster (SSPC) – Ireland, the on-demand version of  Calibration Free Supersaturation Assessment and Control for the Development and Optimization of Crystallization Processes is now available.

View the Calibration Free Supersaturation Assessment and Control for the Development and Optimization of Crystallization Processes on-demand webinar.

If you are interested in discussing Crystallization topics with Mark Barrett and over 300 others who work in Crystallization, I invite you to join the LinkedIn Crystallization Community.

Pfizer YouTube video: Process Analytical Technology – Using Mid-IR spectroscopy to monitor a telescoped chemical reaction

Ian Clegg, an Associate Research Fellow at Pfizer Global Research and Development Sandwich Laboratories, United Kingdom recently posted a discussion on LinkedIn’s Process Analytical Technology (PAT) group site titled “PAT data (Mid-IR) posted onto YouTube.”

This YouTube video is entitled “Process Analytical Technology: Using Mid-IR spectroscopy to monitor a telescoped chemical reaction.”

httpv://www.youtube.com/watch?v=EWec0O6WtUU

In this video, 3 sequential chemical reactions are run in one vessel without stopping or isolating between reactions, and ReactIR™ (real-time in situ reaction analysis) is used to monitor all 3 reaction phases. All of the key reagents, intermediates and products produce unique peaks which show reaction progression without having to take samples. The video shows the spectra of the reaction as a function of time and how the spectra change. The video shows clearly which peaks were monitored and to which components those peaks correlate.

Continue reading