Wednesday, November 20, 2013

preparation of 10% Methanolic HCl solution

It is a very economical method to make methanolic HCl. Here we form in situ HCl by mixing methanol with acetyl chloride.

For this, take 4036 micro litre methanol and cool it to 0 degree celcious using ice bath. then add 964 microlitre Acetyl chloride dropwise to it.

Mix it properly. It makes 10% solution of HCl in methanol. 

Friday, October 11, 2013

How to search Scholarly scientific Articles Online

When your teacher, lecturer, and internal common sense tell you that there's a lot of misinformed hogwash and misinformation online, it's not all bad news! You can find scholarly articles online with peer review and referencing up to your eyeballs. The utility and reliability of the articles is till up to your critical mind but here is how to go about finding them. This article also tries to highlight where you're more likely to get free access but there may be times when payment is required.
 
1) Turn to Google Scholar. To begin with, this is a good place to search for scholarly works. It can be found at: http://scholar.google.com. It may have your own country's URL ending though, so you can also simply google "Google Scholar" for the local return. This search mechanism provides you with the opportunity to search across numerous disciplines and sources. It searches journals, theses, abstracts, articles, etc.
  • Simple keyword searches may not be as beneficial in terms of returns as in the normal Google search engine. Try using the advanced search options to search for phrases, titles, authors, etc.
  • The returns in the search will be a list of citations in order of relevance (rather than chronologically as you usually get with academic article searches). When you click on one, it will give you publication information, such as the name of the journal, date of publication and the publisher. If you click on the article title, you'll get more information and possibly be taken to an abstract or the full text (meaning you can access the article free-of-charge). If the full text does not appear, you will usually get linked straight to the publisher's page or a public database if there is one.

2) search in http://www.ncbi.nlm.nih.gov/pubmed "Pubmed" search.


3) Search in Sciencedirect
try in http://www.sciencedirect.com/


4) Look at the individual websites of well known journal publishers. These will contain a lot of abstracts that can be downloaded with payment, although sometimes they are free of charge as well. Some journal publishers provide periods of time when articles are available for free in particular disciplines such as the social sciences. However, this option is likely to require payment for much of the access unless you are a student or employee of an educational institution or employee of a firm/corporation that subscribes to the relevant journals.


5) Visit the DOAJ. This is the Directory of Open Access Journals and it is found at: http://www.doaj.org/. As its name suggests, it is free of charge and here you can search for quality controlled scientific and scholarly journals in a wide range of fields and languages.

6) Check out professional articles that have been produced by professional firms and professional societies. In the areas of law, medicine, engineering, psychology, and other professions, you can often find reputable articles offering guidance from top people in their professions. Partly marketing, partly ongoing information for continued learning for professionals, these are often freely available to anyone interested in checking them out.


7) Check out universities. A number of universities are taking a very open approach to providing scholarly articles to the general public, which is an excellent initiative because the more people who have correct facts in this world, the better. You'll need to hunt around to find which universities have a more open policy on providing access to articles online.


Tips:

  • If you find that an article you want requires payment, don't give up just yet. Try your local library's electronic access first to see if they subscribe to the relevant journal or to see if they can order it in for you. And if you know someone studying at university or working in a professional capacity, you might be able to ask them to kindly look up an article for you if they have access to a particular journal.
  • Search for "gateways" to free journals online.

source : http://www.wikihow.com/Find-Scholarly-Articles-Online

Thursday, August 8, 2013

drying of Dimethysulfoxide DMSO

I need dry DMSO for a reaction.Dimethyl sulfoxide (DMSO) is a hygroscopic material. I am suggesting here common methods to dry DMSO.
  1. Vacuum Distillation Method. A convenient method of preparing nearly anhydrous DMSO is to add approximately 20% excess DMSO to the reaction vessel and remove the excess and water by slow distillation through a packed column under vacuum.To distill this nearly anhydrous DMSO, non- jointed, all-glass equipment is required. For the majority of applications, removal of most of the water as a distillation forerun is adequate. It is convenient and requires no special equipment. For cases where very dry DMSO is needed, the next method gives a product with negligible water content.
  2. Molecular Sieves Drying Method. DMSO can be dried to 10 ppm water or less using Linde molecular sieves. A glass column (5' x 1" ID )was packed with one pound molecular sieves (4Å, 14 x 30 mesh). It was activated by heating 16 hours at 325°C, with an ar- gon flow of 6-7 ft 3 /hr. Thirty liters of DMSO with 270 ppm (0.027%) water were passed through this column. At the mid- point, the DMSO may contained 6-10 ppm water. The second half may contain 15-30 ppm. Column regeneration requires washing the column first with DMSO containing 10% water, then 50% DMSO-50% water and finally with water. An extreme heat buildup results from an initial water wash due to heat of solution of DMSO. Repeat the activa- tion step described above after the wash. For this Molecular sieve of 4nm is used.
  3. Distillation from CaH 2 : Distillation from calcium hydride has been widely used in literature reports. However, this procedure has been found to be less effective and less convenient than the first two methods described above. Typically, calcium hydride powder is stirred with DMSO in a flask vented through a phosphorus pentoxide tube. After 18 hours, the distillate (bp 4 mm Hg, 64°C) may contain 90 ppm water. After 7 days exposure, the distillate may still contain 25 ppm water. 
References
  1. http://www.gaylordchemical.com/index.php?page=109b-dmso-drying-dimethyl-sulfoxide
  2. http://delloyd.50megs.com/moreinfo/drying.html