Sciencemadness Discussion Board

The Short Questions Thread (4)

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bfesser - 11-7-2013 at 21:15

In <strong>Nicodem's</strong> words:
Quote:
The <a href="viewthread.php?tid=14239">old thread</a> has become too long so please continue here. Those who never received a proper reply in the old thread, please feel free to repost the question.

Quote:
This is a thread where you can post all those short questions you always wanted to ask but did not consider them worthy of a new thread. You can ask amateur science related questions of all kind as long as you think they are simple enough to be answered by other forum members in a preferably single post.
Consequently, self discipline in avoiding off topic replies is expected.

I would like to add that it would be helpful if you enter "Question"/"Answer" or something similar into the Subject field when posting.

[Edited on 7/12/13 by bfesser]

Question

Variscite - 11-7-2013 at 21:47

I bought some Clean Shot H2SO4 drain cleaner the other day, it says it contains inhibitors in it. It has a clear purple color to it. I was wondering if anyone knew what these inhibitors were? Ive done some research on this, but havent found much, some say they are flourinated. I would also like to know the purity of this stuff, ive read about suspected Se impurities (eek)! What could the applications and constraints be of this H2SO4 vs say technical grade?

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: added to subject field]

[Edited on 7/12/13 by bfesser]

Question

Random - 11-7-2013 at 21:55

How fast does urea hydrolize in Ca(OH)2? I don't care if ammonia is still in solution I just don't want any urea present there.

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: added to subject field]

[Edited on 7/12/13 by bfesser]

chemcam - 12-7-2013 at 10:31

Quote: Originally posted by Variscite  
I bought some Clean Shot H2SO4 drain cleaner ..(cut).. What could the applications and constraints be of this H2SO4 vs say technical grade?


I don't know much about the 'inhibitors' but I have heard it has something to do with its reactivity.
The purple color is just dye to make it seem more dangerous to anyone who uses it. As you know H2SO4 is clear.
What is most likely is that your acid is recycled from some industrial plant, meaning it will be riddled with metal impurities and other unknowns, possibly suspended carbon. The limitations are endless with recycled H2SO4 you don't want to get metal into your energetic materials or it will sensitize them. Whatever you use the acid for will be much harder to get 'pure'.
You should be able to clear it up a little bit by heating on a hot plate (may get rid of water also) but that is very dangerous so wear eye protection and use fume hood. Also, small additions of H2O2 should work as well look into 'Piranha solution' before attempting though.
You should also perform a titration on the acid to get its actual %, it would be nice if you could measure ppm somehow.

Question

Sublimatus - 14-7-2013 at 14:07

If anyone has some certified pure, finely ground anhydrous sodium bromide, could you tell me if it tends to clump or stick together, but then breaks down easily when knocking the bottle?

I'm curious to know if the cohesion I'm seeing is due to moisture or just ionic attraction (I've ground and heated the material to 200 C, so I should think all water has been driven off).

Thank you.

Dr.Bob - 15-7-2013 at 11:53

I know that dry KBr clumps readily due to moisture. But for very dry powders, often static will cause them to hold together in clumps or staticy strings, for lack of a better word, even after they are ground into a fine powder.

Answer (kind of, and to my own question)

Sublimatus - 15-7-2013 at 12:14

Thanks for the input.

The <strike>KBr</strike> NaBr was finely ground after being baked for two hours at 200 C, and then loaded into a glass bottle, which was again heated at 200 C for an hour before removing it from the oven and capping it tightly.

The <strike>KBr</strike> NaBr clumps and reclumps readily, but breaks apart relatively easily when the bottle is knocked. As two hours at 200 C should be long enough to destroy the dihydrate (which melts at 36 C) and completely dry the powder, I'm leaning towards the explanation being ionic attraction or static as you suggest. Also the fact that sodium chloride is sold with anti-clumping and other agents to keep it free flowing leads me to think that this is typical behavior.

Edit: I meant sodium bromide, but wrote potassium bromide. Must've had KBr on the brain after Dr. Bob referred to it.

[Edited on 7/15/2013 by Sublimatus]

[question(s)]

bfesser - 27-7-2013 at 11:36

<em>Q.</em> Why do hotplate manuals say not to cover the surface with Al foil?
<em>Q.</em> I plan to heat asphalt in a soup can on my metal-top hotplate. Will it be okay to put some Al foil on the top just this once?
<em>Q.</em> Should I go buy a fire extinguisher and burn cream, or just pre-dial 911?

[Edited on 27.7.13 by bfesser]

ElectroWin - 27-7-2013 at 12:34

Aluminum is amphoteric, dissolving in either acids or bases; so beware the pH of what you're cooking.

[Edited on 2013-7-27 by ElectroWin]

papaya - 27-7-2013 at 12:35

Why it is prohibited to extinguish a man on fire with the help of fire extinguisher ?

Vargouille - 29-7-2013 at 07:17

Quote: Originally posted by papaya  
Why it is prohibited to extinguish a man on fire with the help of fire extinguisher ?


It depends on the type of extinguisher that you use. CO2 extinguishers are highly compressed, so when they come out they're very cold, which can cause frostbite. Also, if the person is on the ground, the CO2 can suffocate them. Some ABC dry chemical extinguishers are safe because their contents are of negligible toxicity, but you should check their MSDS to make sure. Of course, the person will want to cover their face with their hands if you use a dry chemical extinguisher on them, but other than that it's fairly safe.

http://www.homeofpoi.com/lessons_all/teach/Fire-Extinguisher...

Mailinmypocket - 29-7-2013 at 07:25

Quote: Originally posted by bfesser  
<em>Q.</em> Why do hotplate manuals say not to cover the surface with Al foil?

[Edited on 27.7.13 by bfesser]


I think it may be due to the aluminum reflecting the heat back to the heating surface which may cause problems with the thermostat... My ceramic top plate also says to not heat metal vessels on it, I went against this and heated a stainless steel bowl for a hot water bath. The entire unit became very hot after about an hour- this never happened before when using glass water baths. I could have seen it leading to a failure of some sort if I kept it up. My theory about the aluminum reflecting the heat back may be wrong though- maybe somebody knows more on this.

DJF90 - 29-7-2013 at 13:22

Al foil can trap air pockets which insulate the heating surface, causing the aluminium plate to melt. Peach experienced this first hand IIRC... came back to look at his reaction and found his hotplate had turned to a puddle of molten Al (exaggeration on my part, but it was pretty serious!).

LiD - 1-8-2013 at 04:38

I would like to ask, that if I would react an alkene with OsO4 in methanol, some potassium methoxide and NMO as an oxidant, than what would be my product be?

Or asking in another way: if I use an alcohol instead of water for opening the osmium-alkene intermedier, than would an ether form or not?



Mailinmypocket - 1-8-2013 at 07:56

I'm attempting a hydrogenation reaction and it calls for rhodium catalyst on alumina... I only have a small quantity of rhodium powder, can this be used instead or is it imperative that the rhodium/alumina be used? It is for the synthesis of zingerone btw.

Thanks

kristofvagyok - 1-8-2013 at 08:29

Quote: Originally posted by Mailinmypocket  
I only have a small quantity of rhodium powder, can this be used instead or is it imperative that the rhodium/alumina be used?


The surface of the Rh powder, compared to the Al2O3/Rh is several fold smaller and for heterogenous catalysis this one of the most important thing.

Make some Rh/Al2O3 or Rh/C from the powder, it's not that hard to make and if you regenerate the catalyst properly, it could be used several times.

Mailinmypocket - 1-8-2013 at 10:40

Ah, makes sense. Do you happen to have any facile ways of preparing a rhodium catalyst on alumina or carbon? I'm having a bit of difficulty locating such a procedure...

kristofvagyok - 1-8-2013 at 16:35

From US5597772

Rhodium was next added to the fumace-aged alumina. A
14 g sample of furnace-aged alumina was mixed with an
aqueous solution of rhodium nitrate con-
taining a total of 0.085 grams of rhodium. The mixture was
first dried at room temperature, then at 100° C., and subse-
quently calcined at 550° C. for 4 hours. The process outlined
above constitutes the rhodium impregnation/drying/calcin-
ing step according to Scheme l of FIG. 2 (comparative
example). The catalyst at this point was in the so-called
“fresh” state, designated D-l , with a Rh loading of 0.6 wt %,

Mailinmypocket - 2-8-2013 at 06:00

Quote: Originally posted by kristofvagyok  
From US5597772

Rhodium was next added to the fumace-aged alumina. A
14 g sample of furnace-aged alumina was mixed with an
aqueous solution of rhodium nitrate con-
taining a total of 0.085 grams of rhodium. The mixture was
first dried at room temperature, then at 100° C., and subse-
quently calcined at 550° C. for 4 hours. The process outlined
above constitutes the rhodium impregnation/drying/calcin-
ing step according to Scheme l of FIG. 2 (comparative
example). The catalyst at this point was in the so-called
“fresh” state, designated D-l , with a Rh loading of 0.6 wt %,


Thank you! It sounds like a bit of a challenge but ill give it a shot.

Absorption of Water and HCl by Strong Bases

subsecret - 2-8-2013 at 10:14

My gas generator releases small amounts of HCl gas when it's producing CO2. Additionally, some water vapor is also released. I need a source of clean CO2 for experiments, and I was wondering what the best way tould be to remove these gases. Could I run the output through a tube of sodium hydroxide?

Any help is appreciated.

bfesser - 2-8-2013 at 10:15

You just answered your own question. You'll lose a little CO<sub>2</sub> in the formation of Na<sub>2</sub>CO<sub>3</sub> and NaHCO<sub>3</sub>, however.
Quote:
<table><tr><td><div align="center">13. GAS GENERATORS</div>
(a) <em>Carbon Dioxide, Hydrogen, an Hydrogen Sulphide.</em> The simplest form of generator for these gases is shown in Fig. 7. The solid material, cracked marble for carbon dioxide, feathered zinc for hydrogen, and ferrous sulphide for hydrogen sulphide is placed in the 300-cc. thick-walled generator bottle. The tubes are fitted as shown, and in the drying tube is placed a plug of cotton wool to strain the acid spray out of the gas, or if the gas is to be dried, granulated calcium chloride held in place with a plug of cotton wool on either side. Enough water is poured in through the thistle tube to cover its lower end and then about 5 cc. of 6 <em>N</em> HCl. The gas begins to generate rather slowly, but if one is impatient and adds more acid at once the reaction will soon become so violent as to drive foam out through the delivery tube. After a few minutes add more acid, 1 cc. at a time, in order to keep up the evolution of gas at the desired rate.<br /><br />&ndash; <em>Synthetic Inorganic Chemistry: a Course of Laboratory and Classroom Study for First Year College Students</em>. Blanchard, Phelan, & Davis. 5th ed., Wiley & Sons, 1936.</td><td>figure_7.jpg - 45kB</td></tr></table>
Oh, for fuck's sake! I just realized that we have <a href="http://www.sciencemadness.org/library/books/synthetic_inorganic_chemistry_blanchard_5thed1937.pdf#page=28">this book in the library</a> <img src="../scipics/_pdf.png" />&mdash;pages 18&ndash;19 in the book (28&ndash;29 in the PDF). PDFs of this and other editions are also freely available elsewhere. I need to get used to finding things online rather than immediately jumping to my bookshelves. I'd rather not think about how many times I may have done this in the past. This damned newfangled internets thing! After all that effort of selecting the book from my shelf, finding the section from memory, transcribing the text, taking the photo, carefully cleaning it up in Photoshop... :(

[Edited on 2.8.13 by bfesser]

subsecret - 2-8-2013 at 18:08

Thank you.

ChemistryGhost - 5-8-2013 at 12:05

Can 1,4-dimethoxybenzene be alkylated with ethylene epoxide using Iron(III) chloride?

Grignard Addition to Nitriles

Metacelsus - 9-8-2013 at 17:49

When a Grignard reagent reacts with a nitrile, an imine salt is formed, which is usually hydrolyzed to a ketone.
http://www.chem.ucalgary.ca/courses/350/Carey5th/Ch20/ch20-3...
Is there any way to form an amine from this intermediate imine salt, without going through the ketone?

(For example, sec-butylamine from ethylmagnesium bromide and acetonitrile.)

sonogashira - 10-8-2013 at 02:06

Yes, and in good yields. One may add diborane/THF or methanol/NaBH4 etc. For an example of the former: http://www.sciencedirect.com/science/article/pii/S0040403902...
Search on google scholar; there are plenty of examples and links to freely-accessible papers.

elementcollector1 - 13-8-2013 at 19:05

Does Schweizer's Reagent react with red phosphorus? (I know, cook question, but I can't exactly find a reference...)

sonogashira - 14-8-2013 at 13:50

How small can the incident area of a laser beam be made, in theory and in practice?

elementcollector1 - 14-8-2013 at 14:20

Quote: Originally posted by sonogashira  
How small can the incident area of a laser beam be made, in theory and in practice?

If I had to guess...
In theory: 1 photon wide
In practice: Microscopic (search 'optical tweezers')

confused - 15-8-2013 at 07:22

Im thinking of getting a hotplate stirrer for distillations/refluxes as its hard to get good control of temperature with an open flame...
would a maximum temperature of 350'C work for most common laboratory procedures?
is 350'C sufficent to concentrate sulfuric acid past 95% concentration?
and is there a significant diffrence between aluminium and ceramic top plates?

Varmint - 15-8-2013 at 09:30

sonogashira:

See the link regarding AIRY disk.

http://en.wikipedia.org/wiki/Airy_disk

In essence, the shorter the wavelength, the smaller the spot (which is why Blu-Ray holds much more data than the DVD which is written (or meant to be read) by a red laser beam.

No matter the wavelength, a single photon sized spot is absolutely out of the question.

This has applications in the real world as well, note how even cellphone cameras are reaching very high mega-pixel counts? At some point the sensors cannot be made any smaller because the airy disk will cover adjacent cells, rendering further increases in sensor pixel density useless.

Ergo, the sensors have a finite minimum size, after which the senor size must increase to utilize the comparatively "large" dot the airy disk represents for small image features you wish to preserve.

DAS

[Edited on 15-8-2013 by Varmint]

watson.fawkes - 15-8-2013 at 10:13

Quote: Originally posted by Varmint  
At some point the sensors cannot be made any smaller because the airy disk will cover adjacent cells, rendering further increases in sensor pixel density useless.
This is true about geometrical optics, the model in which the Airy disc sits. It's not quite the same with diffractive optics, or other optical models.

But if you're using an ordinary lens with its de facto aperture, I have nothing to disagree with invoking the Airy disk.

UnintentionalChaos - 15-8-2013 at 11:23

Nobody seems to find my questions in these threads, but I am looking to t-Butylate a primary amine (specifically GABA). Can anyone suggest reaction conditions?

sonogashira - 15-8-2013 at 12:38

Thank you Varmint.


"t-Butylate a primary amine (specifically GABA)."
You may make it via THF to Cl(CH2)4OH [with HCl] to Cl(CH2)3COOH to your amine, alternatively. Or GBL to the chloride directly.



[Edited on 15-8-2013 by sonogashira]

UnintentionalChaos - 15-8-2013 at 18:28

Quote: Originally posted by sonogashira  


"t-Butylate a primary amine (specifically GABA)."
You may make it via THF to Cl(CH2)4OH [with HCl] to Cl(CH2)3COOH to your amine, alternatively. Or GBL to the chloride directly.


Disregard the post that used to be here. Found http://www.sciencemadness.org/talk/viewthread.php?tid=8477

Get the distinct impression that it's not happening and I need an alternate route.

[Edited on 8-16-13 by UnintentionalChaos]

Molecular sieves?

Mailinmypocket - 16-8-2013 at 10:32

So, being lucky enough to be a diabetic(T1) I need to use glucose test strips to determine my blood glucose levels. The manufacturer of the strips recently changed the small vials to include a plastic capsule filled with small beads, I immediately took it apart to squirrel away these beads in case they may be of use. My question is, what are they? I'm thinking some sort of molecular sieve (perhaps 4A?) but I'm not sure. There is sadly no MSDS or other information available from the manufacturer either. Given the ingredients, does anyone have a clue of what these things might be?


image.jpg - 138kB image.jpg - 112kB

watson.fawkes - 16-8-2013 at 10:39

Quote: Originally posted by Mailinmypocket  
Given the ingredients, does anyone have a clue of what these things might be?
It's a desiccant. The ingredients on the package have nothing to do with the beads.

Mailinmypocket - 16-8-2013 at 10:56

Hmm... Okay. I thought perhaps the glucose oxidase was oxygen sensitive or something. I wish I knew the composition of this stuff though.

watson.fawkes - 16-8-2013 at 11:11

Quote: Originally posted by Mailinmypocket  
I thought perhaps the glucose oxidase was oxygen sensitive or something. I wish I knew the composition of this stuff though.
It might also be an oxygen scavenger, too. The most common one I've seen, though, is finely divided elemental iron.

As to what the prills are, my first guess, just from the photo, was calcium chloride. If you want to get some indirect evidence, dry them in an oven and weigh. Put them in an "anti-desiccator" with a liquid water source to saturate the atmosphere inside. After a week, weigh them again. Since different desiccants have different capacities to sequester water, it'll give some idea.

elementcollector1 - 18-8-2013 at 21:55

Does 'cryohol' (a mixture of dry ice and ethanol) still work if you replace the ethanol with isopropanol? I think it should, but mine failed to liquefy chlorine and it has me wondering.

EDIT: On that note, are there any alternative cryohol mixes? Dry ice is hard to come by where I am.

[Edited on 19-8-2013 by elementcollector1]

confused - 18-8-2013 at 22:07

you could try acetone if isopropanol doesn't work
It should though, according to wiki, it should reach -77'c

i would say LN2, but since dry ice is already hard to come by...
maybe you could try some form of mechanical cooling, but i doubt it will reach anywhere near dry ice would get you

http://en.wikipedia.org/wiki/List_of_cooling_baths

[Edited on 19-8-2013 by confused]

karlos³ - 2-9-2013 at 19:47

Hello people,
I would like to know if an aromatic amide can in a one-pot reaction be halogenated to the N-haloamide and on the aromatic ring too?
To be specific, im talking about the hofmann rearrangement, which I want to use to make 4-chloroaniline from benzamide with TCCA in methanol, then rearrangement with lye.
I cant find any reason why it wont work if I would just use two times the stochiometric amount of TCCA and take two times more care during addition?

There are papers out there for the use of TCCA for N-chloroamides/hofmann rearrangement, there are papers out there for aromatic halogenation, but i cant find any thats stating this will not work, or why it is undesirable?
Or maybe its just rare someone wants to do such a thing?

I had some paper which proves my assumption it could be possible, it was stating ring-halogenation of an aromatic amide during a hofmann rearrangement. when hypochlorite solution was used in excess, as a side product.

Seems just logical it would work, as its for both cases an electrophilic chlorination.
Can someone tell me if I missed something?
Or is it indeed possible to make 4-Chloroaniline from Benzamide in one shot?

sonogashira - 3-9-2013 at 00:23

If I recall correctly, you will need acidic conditions to chlorinate the benzene ring. I have some examples of NCS aromatic chlorination using sulphuric acid, or acetic acid, so I imagine that TCCA should need similar conditions. Please post the papers that you have on TCCA aromatic chlorination.

karlos³ - 3-9-2013 at 04:42

Yes indeed, my reference use sulfuric acid as well as catalyst, forgot about the conditions needed, that wont do it.

But I got another ref, actually a bromination, with TCCA/NaBr to form tribromoisocyanuric acid/TBCA, in methanol.
Just TBCA in MeOH.
The attached reference for N-haloamide preparation uses just TCCA in MeOH.
How about now, that seems to work in theory?

Could the reaction of TBCA and benzamide lead to 4,N-dibromobenzamide?

I only post both relevant references, since i think i got them from here and dont want to waste polverones bandwidth;).

Attachment: jo00828a039.pdf (149kB)
This file has been downloaded 3251 times

Attachment: A New Regioselective Bromination of Activated Aromatic Rings.pdf (69kB)
This file has been downloaded 1446 times


sonogashira - 4-9-2013 at 03:27

Thanks. Here's a paper for 4-chlorination of N-acetylaniline with TCCA, if it's of any use.


Attachment: 4-chloroaniline.pdf (65kB)
This file has been downloaded 551 times


plante1999 - 9-9-2013 at 11:37

Does anyone have a good plating book (including chromium plating) to refer me to?

A download link would also be highly apprecied, (reference section or U2U).

IrC - 9-9-2013 at 13:18

Quote: Originally posted by plante1999  
Does anyone have a good plating book (including chromium plating) to refer me to?

A download link would also be highly apprecied, (reference section or U2U).


Old books yet still good. Much of the reason I find old books useful is they are free, they also cover making things used in the art, many of the procedures being old but proven are much easier for a home lab to build using available salvage.

http://archive.org/details/electroplatingtr00reet

http://archive.org/details/principleselect00fielgoog

http://archive.org/details/removalofcopperi00somm

http://archive.org/details/practicalelectro00brun

http://archive.org/details/completetreatise00langrich

http://archive.org/details/electrodepositio00languoft

http://archive.org/details/practicalelectro00bedeuoft

http://archive.org/details/acompletetreati00langgoog

http://archive.org/details/electroplatingma00harp

http://archive.org/details/structureofchrom93353kasp

http://archive.org/details/protectivevalueo13333blum

http://archive.org/details/acceleratedtests13451stra

http://archive.org/details/throwingpowerinc41271farb

http://archive.org/details/jresv43n2p101

http://archive.org/details/jresv46n6p472

http://archive.org/details/jstor-41326936

http://archive.org/details/cleaningelectrop02ream

http://archive.org/details/radiochemicalstu18rein

http://archive.org/details/practicalhandboo00trev

http://archive.org/details/bstj59-2-169

http://archive.org/details/cleaningelectrop00ream

http://archive.org/details/TheBrushElectricLightAndElectro-p...

http://archive.org/details/electroplatinga00wattgoog

http://archive.org/details/TheBrushElectricLightAndElectro-p...

http://archive.org/details/practicalelectro00bede

http://archive.org/details/electroplatingtr00barcrich

http://archive.org/details/electroplatingwi00hasl


[Edited on 9-10-2013 by IrC]

Variscite - 9-9-2013 at 17:28

What are the pros and cons of a 14/20 setup vs a 24/40 setup for the home chemist? As in learning the reactions, I know it would be fine. But what about a reasonable amount of reagent preparation, too small to be useful?

methOH vs. methoxide

roXefeller - 9-9-2013 at 17:32

I've been trolling the forums for a couple years now, but this is obviously my first question: Why do many people discussing reagents abbreviate to methOH or methoxide? I can generally study the process occuring and figure whether it is methanol (methyl with hydroxyl) or a base like NaOH dissolved in methanol. But why would we want to default to these less exacting abbreviations in a discipline that usually requires exact naming (nitrite v. nitrate, nitrous oxide v. nitric oxide, or the many o- m- p-1- 2- etc variations of functional groups on a benzene ring)? Thanks so much for the forum. I'm finally able to get back to my chemistry interests after going through a mechanical eng detour.

bfesser - 9-9-2013 at 18:18

This is the first I've seen "methOH." MeOH is common and acceptable. Here are a couple references you may find helpful:

<strong><a href="http://bama.ua.edu/~blacksto/SCB_page/SCB%20site/research%20handouts/joc_abbreviations.pdf" target="_blank">Standard Abbreviations and Acronyms</a></strong> <img src="../scipics/_pdf.png" /> (The Journal of Organic Chemistry)
<strong><a href="http://www.chem.wisc.edu/areas/reich/handouts/acronyms.pdf" target="_blank">Organic Chemistry Acronyms</a></strong> <img src="../scipics/_pdf.png" /> (UW-Madison Chem.)

<em>Welcome to [active] Science Madness!</em>

Question

confused - 12-9-2013 at 07:18

Hi,
what causes the errosion of carbon electrodes during electrolysis of a copper sulfate solution?

elementcollector1 - 12-9-2013 at 11:20

Quote: Originally posted by confused  
Hi,
what causes the errosion of carbon electrodes during electrolysis of a copper sulfate solution?

Mainly the production of sulfuric acid. Carbon seems to be soluble in it to some extent, and carbon electrodes may form some sort of intercalated 'graphite oxide' from the oxygen of the water which degrades the structure.
This is all speculation, though.

manimal - 13-9-2013 at 00:57

In esterifications using acid anhydrides, is the anhydride a uniquely (more) reactive species that reacts more readily with an alcohol than does the carboxylic acid alone, or does the anhydride facilitate the reaction only by removing formed water?

DraconicAcid - 13-9-2013 at 10:21

Quote: Originally posted by manimal  
In esterifications using acid anhydrides, is the anhydride a uniquely (more) reactive species that reacts more readily with an alcohol than does the carboxylic acid alone, or does the anhydride facilitate the reaction only by removing formed water?


It's more reactive. The fact that it doesn't produce water to reverse the reaction is a bonus.

sonogashira - 16-9-2013 at 07:48

Is it possible to buy an electrical heater that is shaped like this, so that I may insert it into a tube? I don't know what they may be called. Ideally only the top would get hot, but it is not too important.


[Edited on 16-9-2013 by sonogashira]

confused - 16-9-2013 at 09:31

http://www.made-in-china.com/showroom/sonnong168/product-det...

http://zh4u.en.alibaba.com/product/1150672030-200418709/MCH_...

would this be close to what you are looking for?

i searched for "ceramic heating element" in google

sonogashira - 16-9-2013 at 12:11

Thanks. That might do. :)

Squall181 - 16-9-2013 at 16:47

I know that highly concentrated solutions of sodium hydroxides can dissolve glass.
Is this also true if the sodium hydroxide had been dissolved in say 90% ethanol?

Seems to me like it should but I am not sure. I have been looking at some XPS data and there seems to be a silicon peak in the scan (of these particular samples), and the only source I can think for this would be from the glass beaker that was used to prepare the reaction mixture.

Gooferking Science - 17-9-2013 at 04:26

What is the best source to get chemicals from? Sigma-Aldrich?

elementcollector1 - 17-9-2013 at 05:08

Quote: Originally posted by Gooferking Science  
What is the best source to get chemicals from? Sigma-Aldrich?

Definitely not. Try elemental-scientific, United Nuclear, HMS-Beagle, and/or Metallium.

woelen - 17-9-2013 at 06:17

Quote: Originally posted by Squall181  
I know that highly concentrated solutions of sodium hydroxides can dissolve glass.
Is this also true if the sodium hydroxide had been dissolved in say 90% ethanol?

Seems to me like it should but I am not sure. I have been looking at some XPS data and there seems to be a silicon peak in the scan (of these particular samples), and the only source I can think for this would be from the glass beaker that was used to prepare the reaction mixture.

Yes, as long as there is water in the mix, it is capable of attacking glass. The etching process will lead to formation of soluble silicates, which probably also are somewhat soluble in 90% ethanol.

Metacelsus - 17-9-2013 at 11:03

It all depends on the chemical. Sigma sells a great variety and has consistent purity, but their prices are insane. For amateur purposes, try your local hardware store or Ebay first. You may want to synthesize the chemical you want yourself if the precursors are cheap but the product is hard to get due to shipping restrictions (like bromine or nitric acid).

Dr.Bob - 19-9-2013 at 12:57

Quote: Originally posted by Squall181  
I know that highly concentrated solutions of sodium hydroxides can dissolve glass. Is this also true if the sodium hydroxide had been dissolved in say 90% ethanol?


Yes, this is also known as a "base bath", where a mixture of alcohol and strong base is used to clean glass, and will etch it is left long enough, or just dissolve glass frits.

Bob

Gooferking Science - 20-9-2013 at 18:30

Where can I buy 10 - 20 ml ampoules at a decent price? I can't find them anywhere.....

Boron Trioxide - 21-9-2013 at 08:25

I was planning on purchasing some manganese sulphate however I cannot seem to find a Canadian supplier and all american suppliers will not ship to Canada, specifically I was looking at Alpha Chemical's product.

Is there a reason it is so hard to find in Canada, I cannot think of any reason for it to be banned, and I looked around and couldn't see any law against it? So do you think if I ship from the US it will get stopped at Customs?

SHADYCHASE54 - 21-9-2013 at 15:15

I have a quick question regarding cation exchange resin H+

My question is will H+ resin exchange only Na cation in a inorganic salt or can it swap other inorganic salts such as K, Li or Cs. I realize that the H+ cation exchanger would have the greatest affinity for Na cations' however in the absence of Na cations will the resin also exchange other alkaline metal cations?

kristofvagyok - 21-9-2013 at 15:47

Quote: Originally posted by SHADYCHASE54  
My question is will H+ resin exchange only Na cation in a inorganic salt or can it swap other inorganic salts such as K, Li or Cs.

The proper question would be, that does sulfuric acid react with all alkali salts on the same way? The answer is yes. However a little difference will be, depending on the alkali, but at all, it is really similar.

What are strongly acidic ion exchange resins?

matrix: styrene-divinylbenzene (gel)
matrix active group: sulfonic acid functional group

bfesser - 21-9-2013 at 15:53

Quote: Originally posted by sonogashira  
Is it possible to buy an electrical heater that is shaped like this, so that I may insert it into a tube? I don't know what they may be called. Ideally only the top would get hot, but it is not too important.
Cylindrical? They're called cartridge heaters or cartridge heating elements.
Quote: Originally posted by Gooferking Science  
What is the best source to get chemicals from? Sigma-Aldrich?
Keep working on a positive posting record, then request access to References. I have compiled a fairly comprehensive list of suppliers and manufacturers, including many which are known to be amateur friendly. (It was moved there to keep it secret... not my idea.) Which reminds me, it's been a while since I last updated it...

[Edited on 21.9.13 by bfesser]

confused - 21-9-2013 at 16:10

Quote: Originally posted by Gooferking Science  
Where can I buy 10 - 20 ml ampoules at a decent price? I can't find them anywhere.....


you can make ampoules out of glass tubing

http://www.youtube.com/watch?v=cve_D3tWlzE

Question:

Pyro - 11-10-2013 at 14:22

Does anybody have an empty 1250ml amber glass pharmapac bottle they could weigh for me?
like this one in the foreground:
2013-05-08 14.03.06.jpg - 94kB

In this bottle is that dry unstabilized RP, I need to know approximately how much it contains but don't want to risk emptying it just to weigh it. (total mass=+-1000g)

Answer:
you can buy ampules at http://www.sciplus.com/ in the US and at:
http://www.ebay.nl/itm/275-st-5-ml-leer-Ampullen-aus-Glas-/3...
check his other listings, he has ampules in sizes 1ml-5ml-10ml is clear and brown glass

[Edited on 11-10-2013 by Pyro]

[Edited on 11-10-2013 by Pyro]

Mailinmypocket - 11-10-2013 at 15:39

Can't help, per se. But as far as weight goes you would be better off dumping the contents into something clean, weighing/taring the bottle, filling etc. I have found that identical vials, bottles, jars etc always have differences in the 1-1.5g range. Is this an issue or are you looking for an average mass?

Pyro - 12-10-2013 at 03:01

I mentioned why I didn't want to empty it as its over half full of finely powdered, dry and unstabilized RP. don't want to take the risk of transferring all that for the sake of weighing.
I just need an estimate on how much RP I have left, or might face a nasty surprise when I run out in the middle of a synth.

Gooferking Science - 13-10-2013 at 13:27

Could chloroform be made by bubbling chlorine gas through acetone with a bit of sodium hydroxide dissolved in it? The definition of the haloform reaction is "the excessive halogenation of a methyl ketone in the presence of a base." so I figure it should work...

UnintentionalChaos - 13-10-2013 at 13:40

Quote: Originally posted by Gooferking Science  
Could chloroform be made by bubbling chlorine gas through acetone with a bit of sodium hydroxide dissolved in it? The definition of the haloform reaction is "the excessive halogenation of a methyl ketone in the presence of a base." so I figure it should work...


You'd be better off bubbling Cl2 into sodium hydroxide solution and then adding acetone. or just buying unscented bleach by the gallon and skip the chlorine gas all together.

bismuthate - 13-10-2013 at 13:46

I believe that this makes chloroacetone with some NaOCl. Some chloroform would be formed hovever not much due to the reaction of chlorine and acetone also you would need quite a bit of sodium hydroxide not just a bit.
http://en.wikipedia.org/wiki/Chloroacetone
I would make chloroform from NaOCl bleach and acetone.
P.S. I found a unique way to make chloroacetone for anyone who needs it.
http://www.erowid.org/archive/rhodium/chemistry/haloacetone....

Question

Sublimatus - 15-10-2013 at 14:05

What's a typical amount of 4A molecular sieves to add to say 500 mL of ether to maintain dryness in storage? Enough to cover the bottom of the bottle? Less?

Metacelsus - 15-10-2013 at 17:42

What conditions are you storing it under, and for how long? A good starting estimate would be about 1 gram per 100 milliliters.

Sublimatus - 16-10-2013 at 14:17

It's stored in a brown glass bottle with a teflon-lined plastic cap, at room temperature, in a flammables cabinet. I'd like to put some molecular sieves in the bottle to scrub up any water that might end up in there anytime the bottle is opened.

What is your 1 gram per 100 milliliters suggestion based on?

My best guess is that the maximum I would ever put in is 34 grams. I came to this number by the following calculation:

500 mL of ether can dissolve 7.5 grams of water at room temperature (1.5 grams H20/100mL ether).

The manufacturer of these sieves claims they will absorb 22% of their own weight in water at 25 C.

To absorb the maxmium 7.5 grams would require 34 grams of molecular sieves.

That seems like overkill, but it's the only reasoned estimate I can come up with without advice from someone else with experience.

Metacelsus - 16-10-2013 at 14:47

My estimate is based on the procedure we use to store NMR solvents at the lab I work at. I assume you will pre-dry your ether, and the sieves are just to keep it dry during storage. In that case, you probably won't need 34 grams of sieves.

Sublimatus - 16-10-2013 at 14:55

I think you're right. The 34 grams was the maximum I could imagine using, and really seems like overkill.

Thank you for your input, Cheddite Cheese.

bismuthate - 19-10-2013 at 04:44

How would NaBH4 react with chlorine?

Metacelsus - 19-10-2013 at 07:17

My guess:

NaBH4 + 4 Cl2 -> NaCl + BCl3 + 4 HCl

bismuthate - 19-10-2013 at 09:37

Thank you that could be a unique way to make boron if passed over a reducing agent.

Metacelsus - 19-10-2013 at 11:09

In my opinion, it would be near sacrilege to use (waste) sodium borohydride to isolate boron. Why not reduce boron trioxide with magnesium or aluminum?

bismuthate - 19-10-2013 at 11:15

Don't worry I'm would be making my own impure LiBH4 from boric acid, methanol, lithium ( I can get as much as I need), and hydrogen. I am in an unfortunate circumstance that does not allow me to make the trioxide.
Plus I'm making a creative method:D.

How to make copper gluconate

Hegi - 21-10-2013 at 10:41

I really need help with this reaction. I´m trying to make as many as possible compounds of copper and now my challenge is to make copper(II) gluconate. The idea is to get some gluconic acid and let it react with copper carbonate or copper hydroxide. I tried to oxidize glucose by reaction with iodine potassium iodide solution and sodium hydroxide then adding copper carbonate, the final solution was green/blue .. after heating it up it completely lost the color and nothing crystallized out after evaporating water. Anoyone knows where the problem is or better way to make my reaction succesful? :/

[Edited on 21-10-2013 by Hegi]

turd - 1-11-2013 at 05:37

In Tetrahedron 46 (1990), p. 7454 beta-nitrostyrene is reduced to the amine with BH3/THF generated in situ. Hydrolysis is performed with 1N HCl at 80-85°C for 2 h.

Is this really necessary? I thought boranes can be hydrolized by acidification at RT?

DJF90 - 2-11-2013 at 03:12

Borane itself is very readily quenched by the addition of water at 0*C. In the reduction of amides and nitro groups however, the product amine complexes any excess borane as the amine-borane adduct, which can be a great deal more difficult to hydrolyse (and thus release the free amine). Heating with 1M HCl is a common method, but I've found a patent (http://www.google.com/patents/WO2007106459A2) that suggests methanolysis in the presence of a catalytic amount of transition metal salt at ambient conditions. I suspect the amine tetramethylborate salt that results is readily hydrolysed by dilute acid, or perhaps even water.

[Edited on 2-11-2013 by DJF90]

turd - 3-11-2013 at 01:03

Thanks! That makes sense. I never realized amine/borane adducts were that stable. :o

Question

confused - 3-11-2013 at 01:04

Im thinking of sythesizing some sodium hydroxide since its impossible to buy it where i live

would this reaction work?
Ca(OH)2(aq) + Na2CO3(s) → CaCO3↓ + 2 NaOH(aq)
the solution would then be filtered to remove the CaCO3 and be evapourated to dryness in a suitable container to resist corrosion.

any idea on what container to use?
I'd rather not use glass as i dont want to contaminate the product with silicates.



[Edited on 3-11-2013 by confused]

bismuthate - 3-11-2013 at 03:50

NO! That reaction will not work, they just won't react.
You can make it by eletolysis.
gloss is just fine.

[Edited on 3-11-2013 by bismuthate]

plante1999 - 3-11-2013 at 04:07

It will work, simpl have to boil the two together long enough. It used to be an industrial process.

bismuthate - 3-11-2013 at 04:16

Oh! Well then I apologize. You shouldn't use glass for this one.

confused - 3-11-2013 at 04:29

in which case, what container would you reccomend that resists strong bases at elevated temperature

bismuthate - 3-11-2013 at 04:34

Well, steel works along with copper plated containers.

hyfalcon - 3-11-2013 at 04:43

Nickel is resistant all the way to molten NaOH.

[Edited on 3-11-2013 by hyfalcon]

bismuthate - 3-11-2013 at 04:52

Try aluminum *makes troll face*
You can silver plate glass and plate nickel or copper over that.There's a whole thread on it.

confused - 3-11-2013 at 05:03

would stainless steel work?

Gooferking Science - 3-11-2013 at 05:52

Take a look at this neon sign transformer. http://www.ebay.com/itm/NEW-12-000-volt-12kV-NEON-PRO-SIGN-P...

If you look at the description, it has a whole long speech about it not being able to be used as a power supply for jacob's ladders, tesla coils, ect... It also says trying to use it for something like that will void the warranty. Here's my question: Are solid state NST's like this unable to be used for anything other than neon signs, or are they just trying to deter people from using them for those projects? (I don't care about voiding the warranty)

confused - 3-11-2013 at 07:26

that seems to be one of the newer switch mode power supplies their alot higher frequency than iron cored NST. Im not entirely sure how it will affect using it for such projects.

Ideally you would want to use a iron cored neon sign transformer for such projects. But i can see how shipping would be a killer, try and find somewhere that makes neon signs, they'll probably have a few NSTs lying around

Quote:
The newer switch mode NST’s are not ideal for Tesla coil use as they have built in GFI ground fault protection, short circuit protection and their components cannot withstand high frequency radio currents – they will simply be fried if they work at all under Tesla coil conditions!

http://www.google.com.sg/url?sa=t&rct=j&q=&esrc=...

[Edited on 3-11-2013 by confused]

Is this reaction possible?

LiD - 10-11-2013 at 09:11



I've been wondering that nforming polyethyleneoxide and polyethyleneglycol is a well known reaction, what could be done with basic or acidic catalyst, but high molecular weight polymerc could be broken down? I've been wondering on producing dioxane from PEG, anyone any idea?

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