Comments for PMGB http://pmgb.wordpress.com chemical reaction procedures Tue, 10 Nov 2009 16:18:40 +0000 http://wordpress.com/ hourly 1 Comment on About by pmgb http://pmgb.wordpress.com/about/#comment-142 pmgb Tue, 10 Nov 2009 16:18:40 +0000 #comment-142 Thank you. Thank you.

]]> Comment on About by William Lee http://pmgb.wordpress.com/about/#comment-141 William Lee Mon, 09 Nov 2009 18:47:02 +0000 #comment-141 Our website Science.org is a informational databases and online news publication for anything and everything related to science and technology. We recently ran a poll asking our website users regarding what online informational resources they use to keep up to date or even to simply find great information. It seems many of our users have labeled your blog as an excellent source of Space information. We have reviewed your blog and must say, we absolutely love the information you have made available to the public and would love to make your blog a part of our top science blogs. After browsing your blog, our research team has decided to award you a Top science Blogs award banner. Our website Science.org is a informational databases and online news publication for anything and everything related to science and technology. We recently ran a poll asking our website users regarding what online informational resources they use to keep up to date or even to simply find great information. It seems many of our users have labeled your blog as an excellent source of Space information. We have reviewed your blog and must say, we absolutely love the information you have made available to the public and would love to make your blog a part of our top science blogs. After browsing your blog, our research team has decided to award you a Top science Blogs award banner.

]]> Comment on HCl and other salts by pmgb http://pmgb.wordpress.com/2008/03/25/amine-hcl-salt-to-free-base-and-vice-versa/#comment-137 pmgb Thu, 05 Feb 2009 18:16:11 +0000 http://pmgb.wordpress.com/?p=30#comment-137 Thank you. How much acetyl chloride you add to how much ethanol to make 2N ethanolic HCl? Thank you. How much acetyl chloride you add to how much ethanol to make 2N ethanolic HCl?

]]> Comment on HCl and other salts by Steve http://pmgb.wordpress.com/2008/03/25/amine-hcl-salt-to-free-base-and-vice-versa/#comment-136 Steve Thu, 05 Feb 2009 05:47:11 +0000 http://pmgb.wordpress.com/?p=30#comment-136 Patrick, Another option is ethanolic HCl, easily prepared by the (slow) addition of acetyl chloride to ethanol. To the protected amine in a minimal amount of ethanol add slight excess of the HCl solution (I prepare a 2N solution, keeps well on the shelf) and reflux ~20 min. Often nice crystals can be precipitated (after filtration!) with the addition of ether and cooling, or in the fridge overnight. Patrick,

Another option is ethanolic HCl, easily prepared by the (slow) addition of acetyl chloride to ethanol. To the protected amine in a minimal amount of ethanol add slight excess of the HCl solution (I prepare a 2N solution, keeps well on the shelf) and reflux ~20 min. Often nice crystals can be precipitated (after filtration!) with the addition of ether and cooling, or in the fridge overnight.

]]> Comment on Reduction of esters by james http://pmgb.wordpress.com/2008/03/21/reduction-of-esters/#comment-133 james Wed, 21 Jan 2009 11:15:31 +0000 http://pmgb.wordpress.com/2008/03/21/reduction-of-esters/#comment-133 I saw http://pmgb.wordpress.com/2008/03/21/reduction-of-esters/ and wanted to mention a useful site: http://www.FreePatentsOnline.com It provides free patent searching, free PDF downloading, allows annoting documents and sharing them, and free alerts for new documents. If you have a spot, a link to let your users know abou the site would be great. I saw http://pmgb.wordpress.com/2008/03/21/reduction-of-esters/ and wanted to mention a useful site: http://www.FreePatentsOnline.com

It provides free patent searching, free PDF downloading, allows annoting documents and sharing them, and free alerts for new documents.

If you have a spot, a link to let your users know abou the site would be great.

]]> Comment on Mono N-alkylation by ian http://pmgb.wordpress.com/2008/03/23/n-alkylation-of-primary-amines-to-secondary-amines/#comment-132 ian Wed, 21 Jan 2009 03:02:56 +0000 http://pmgb.wordpress.com/?p=7#comment-132 iodo is better leaving group the rxn could just be run longer in the case of hindered bromides. the reason yeilds are low is water in inhibiting the sn2 reaction. also noted the higher dielectric constant aprotic solvents give better yeilds and selectivity condidered dimethyl sulfone? iodo is better leaving group the rxn could just be run longer in the case of hindered bromides.
the reason yeilds are low is water in inhibiting the sn2 reaction.
also noted the higher dielectric constant aprotic solvents give better yeilds and selectivity
condidered dimethyl sulfone?

]]> Comment on HCl and other salts by Bookmarks about Freebase http://pmgb.wordpress.com/2008/03/25/amine-hcl-salt-to-free-base-and-vice-versa/#comment-131 Bookmarks about Freebase Sun, 18 Jan 2009 18:30:39 +0000 http://pmgb.wordpress.com/?p=30#comment-131 [...] - bookmarked by 3 members originally found by alink on 2008-12-19 Amine HCl salt to free base and vice versa http://pmgb.wordpress.com/2008/03/25/amine-hcl-salt-to-free-base-and-vice-versa/ - bookmarked by 1 [...] [...] – bookmarked by 3 members originally found by alink on 2008-12-19 Amine HCl salt to free base and vice versa http://pmgb.wordpress.com/2008/03/25/amine-hcl-salt-to-free-base-and-vice-versa/ – bookmarked by 1 [...]

]]> Comment on HCl and other salts by bw http://pmgb.wordpress.com/2008/03/25/amine-hcl-salt-to-free-base-and-vice-versa/#comment-127 bw Thu, 09 Oct 2008 18:58:02 +0000 http://pmgb.wordpress.com/?p=30#comment-127 HCl in ether can be made by adding sulfuric acid to NaCl and bubbling the resulting HCl gas into the ether. HCl in ether can be made by adding sulfuric acid to NaCl and bubbling the resulting HCl gas into the ether.

]]> Comment on Selective cleavage of Arylacetates to Phenols by milkshake http://pmgb.wordpress.com/2008/09/30/selective-cleavage-of-arylacetates-to-phenols/#comment-125 milkshake Thu, 02 Oct 2008 20:34:30 +0000 http://pmgb.wordpress.com/?p=104#comment-125 I was always using neat BBr3, uncomplexed, in DCM on ice bath, then warm up to RT. BBr3 It is one smoky nasty brownish badass liquid. I think the smoke comes from the water fog forming upon hydratation of anhydrous HBr. All anhydrous volatile strong acids smoke, and so do halides that hydrolyse instantly, SiCl4, TiCl4 etc I was always using neat BBr3, uncomplexed, in DCM on ice bath, then warm up to RT.

BBr3 It is one smoky nasty brownish badass liquid. I think the smoke comes from the water fog forming upon hydratation of anhydrous HBr. All anhydrous volatile strong acids smoke, and so do halides that hydrolyse instantly, SiCl4, TiCl4 etc

]]> Comment on Selective cleavage of Arylacetates to Phenols by pmgb http://pmgb.wordpress.com/2008/09/30/selective-cleavage-of-arylacetates-to-phenols/#comment-124 pmgb Thu, 02 Oct 2008 16:03:23 +0000 http://pmgb.wordpress.com/?p=104#comment-124 I have a question Milkshake. Did you ever use BBr3.(CH3)2S complex for O-demethylation. I have used BBr3.(CH3)2S complex in two cases but it seems like it does not work. Recently I tried to O-demethylate ethyl 4-methoxy-2-nitrobenzoate by refluxing it with 1.2 eq of BBr3.(CH3)2S complex in 1,2-dichloroethane for 12 h. The solution turned black but I recovered most of the starting material back. I suspect the quality BBr3.(CH3)2S complex from Aldrich. Why does BBr3.(CH3)2S complex fume so much when you open the bottle? I have a question Milkshake. Did you ever use BBr3.(CH3)2S complex for O-demethylation. I have used BBr3.(CH3)2S complex in two cases but it seems like it does not work. Recently I tried to O-demethylate ethyl 4-methoxy-2-nitrobenzoate by refluxing it with 1.2 eq of BBr3.(CH3)2S complex in 1,2-dichloroethane for 12 h. The solution turned black but I recovered most of the starting material back. I suspect the quality BBr3.(CH3)2S complex from Aldrich. Why does BBr3.(CH3)2S complex fume so much when you open the bottle?

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