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byko3y
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Hypochlorites give carboxylic acids as a thermodynamically favored product.
On primary carbons there's no carbocations, because those would be to unstable to form. Primary halide undergoes only Sn2 reaction, for this reason
primary alkyl halide, benzyl halide, allyl halide, etc are the best alkylating agents.
Feel free to proof me wrong.
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CuReUS
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reference ?
| Quote: | | On primary carbons there's no carbocations, because those would be to unstable to form. Primary halide undergoes only Sn2 reaction
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there will be a rearrangement
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Templar
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While you're at it, you can confine yourself there was well. Science is still science, regardless if the "state" deems it to be "evil".
Ketene is not fun to play with. Aside from its high toxicity and probably carcinogenic nature, the coils of nichrome used need to be cleaned regularly
due to pyrolysis products and carbon that deposits on it from side reactions with the acetone.
Purging the apparatus, opening it, cleaning carbon off nichrome, and then resuming. There is high potential for exposure.
Maybe the platinum wire method could be cleaned by simply running current through it while air is blown over it, or oxygen.
I never found out how well the sulfur/bromine and sodium acetate method for acetic anhydride worked. Cool reaction, but probably quite messy.
He who fights with monsters should be careful lest he thereby become a monster. And if thou gaze long into an abyss, the abyss will also gaze into
thee.
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DJF90
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Quote: Originally posted by byko3y  |
On primary carbons there's no carbocations, because those would be to unstable to form. Primary halide undergoes only Sn2 reaction, for this reason
primary alkyl halide, benzyl halide, allyl halide, etc are the best alkylating agents.
Feel free to proof me wrong. |
Under typical reaction conditions, the SN2 reaction is greatly favoured over the SN1 pathway. This does not mean that both
cannot occur simultaneously, just that the rate of the SN2 pathway is much much faster. Itis worth noting that CH3+
and CH5+ have both been observed experimentally, but under very different conditions compared to what is employed for a typical
nucleophilic displacement reaction. Benzylic and allylic halides are great electrophiles because not only are they primary halides, they are also
activated enough to undergo the SN1 pathway, and in the case of allylic halides, an SN2' pathway also exists.
No there won't, but under basic conditions you may observe E2 elimination leading back to styrene...
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CuReUS
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I always have this confusion.Why won't there be a rearrangement. ?
suppose you had a primary halide with a tertiary carbon next to it.when you hydrolyse it,wont you end up with a tertiary alcohol instead of a primary
one. ?
no take the case of phenyl ethy lbromide.When you hydrolyse it,the primary carbocation formed will rearrange to a more stable benzyl carbocation,and
you will end up with a secondary alcohol instead of the expected product
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DJF90
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I suspect it depends largely on the conditions for hydrolysis, and is probably substrate specific. There should be very little primary carbocation
formed from phenethyl bromide (unless you're using a halophilic lewis acid like Ag+), although I suspect you will see minor quantities of
1-phenylethanol from the benzylic carbocation (via 1,2-hydride shift) I would expect the SN2 pathway to be the dominant one but
wouldn't be surprised if styrene formed as a significant byproduct (via E2 pathway).
[Edited on 22-4-2015 by DJF90]
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byko3y
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CuReUS, do you know what Sn1 and Sn2 are? Because it looks like you don't.
Do you have a real-world example of a primary halide with a ternary carbon adjacent, which rearranges on a hydrolysis?
UPD: and you wanted a reference for alcohol oxidation to acid, here it is https://www.erowid.org/archive/rhodium/chemistry/ether2ester...
[Edited on 22-4-2015 by byko3y]
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morganbw
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Behave,
it is better to give gentle guidance.
None of us know all.
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CuReUS
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while searching for a method to convert aryl halides to phenols,I stumbled upon this old hive thread,where rhodium and other bees discussed about
making a pseudo 2C-B.
http://chemistry.mdma.ch/hiveboard/serious/000122771.html
although a lot of input along with a ton of reference was given,I think they overlooked somethings.
| Quote: | Rhodium
Administrator posted 11-27-98 02:05 PM
--------------------------------------------------------------------------------
Okay, thanks. My original thinking shrunk down to this approach:
(a) Nitrobenzene (I) ==Brominate==>
(b) 3,5-Dibromo-nitrobenzene (II) ==NaOMe=>
(c) 3,5-Dimetoxy-nitrobenzene (III) |
1.rhodium suggested substitution of the dibromo with dimethoxy with NaOMe.But the bromine atoms are meta to the NO2,so the e-withdrawing
effect of the nitro group should not work,right ?
2.drone 342,who was very active in the discussion,was excited that he had come up with a synthesis,by nitrating a phenethylamine,followed by
bromination,methoxylation,reduction of the nitro,diazotisation followed by CuBr
| Quote: | Here's a whole new approach, complete with gleanings from Beilstein:
1) nitration of phenethylamine with HNO3 and H2SO4
2)bromination using FeBr2
3)methoxylation, using CuBr as a catalyst, DMF as the solvent, and MeOH as the reagent. 110 deg C, 6 h, 95% yields
4)Formation of a diazonium complex, follwed by the Sandmeyer reduction to convert the nitro into a bromo substituent in a one-pot-shot
That's it! That's all there is to it! 4 Steps! Now that's good chemistry! I guess I may have been to hasty when I said it'll never be as easy as its
2,5-counterpart. I underestimated myself. Okay, maybe the last step constitutes 5 steps, but they're easy steps to do!
-drone #342
drone 342
Member posted 11-28-98 03:06 PM |
but I have two questions
1.while methoxylation,is there a chance that the side chain amine might get methylated(as MeOH is used)
2.while diazotising,the side chain amine should convert to OH,shouldn't it ?
rhodium seemed to think so too
| Quote: | Rhodium
Administrator posted 12-13-98 10:10 PM
--------------------------------------------------------------------------------
But the nitration of PEA aren't going to be selective at the 4-position, or? And don't you think the aliphatic amine needs to be protected before
going through all those steps? |
but drone was confident(or should I say too confident)
| Quote: | drone 342
Member posted 12-15-98 02:49 PM
--------------------------------------------------------------------------------
Nitration *can* be selective, and in fact, it is fairly so using the techniques described in the methods I listed -- provided a person is careful in
their nitration, the para position is much more favored than ortho. The amine would not have to be protected at all, as far as I can see; nitration
doesn hurt it, bromination doesn hurt it, the aromatic substitution-elimination won't hurt it, reduction is obviously safe, and even the last step is
one pertaining to aryl amines. So, it should be just fine hanging out there.
-drone #342
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[Edited on 18-5-2015 by CuReUS]
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byko3y
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1. It's hard to perform deactivated aromitics halogenation, and even harded to do that with heavily deactivated aromatic, which is a
bromonitrobenzene.
2. >bromination using FeBr2
Bromination of deactivated nitro-aromatic with amino-group will make a huge mess. And there's also a benzylic carbon, that is much more susceptible to
halogenation.
Doing nitration and halogenation on such an unsubstituted ring will lead to a lot of isomers. Toluene nitration gives close to 7:4 ratio of ortho to
para isomers most of the times.
Diazotation can lead to phenols, as well as halobenzenes in case of sandmeyer reaction, and also thiophenols, and even can be aminated with
primary-secondary amine.
Also, I've tried to look at some of his nitration references and I see no nitration there.
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CuReUS
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yes byko,that's exactly what I thought.you seem to have read my mind
I find it funny and strange at the same time that they struggled so much(Rhodium himself)to make a compound that can be made in four steps(according
to me),all steps giving yields >90%,starting from resorcinol methyl ether(you could start from resorcinol and methylate that,but both are dirt
cheap,resorcinol is 8$/kg while the ether is 10$/kg,so I think it would be bettter to just buy it instead of working with dimethyl sulphate).but I
have to admit I used reactions discovered recently,which were not known in 1998.you could still make it with simple reactions,but in that case six
steps are needed and it gives lesser yields(50-70%).
[Edited on 26-5-2015 by CuReUS]
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byko3y
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I have no idea about how you are going to do 3,5-diMeO-alkylbenzene, because resorcinol can't be substituted at meta position, and nucleuphilic
substitution doesn't work on meta to nitro position, as you've already noticed.
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CuReUS
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well byko,organic chemistry is full of reactions that give unexpected results,you just have to patient enough to find them
I don't think posting the route here would be a good idea,as others might misinterpret it as drug discussion,but it can be done.
[Edited on 26-5-2015 by CuReUS]
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Morkva
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Cureus, you seem to have a strainge confidence, an odd swagger!
Might I suggest you are possessed by demons?
An "oversight by meth cooks" is a suggestive phrase: these could not be a homogenous group: a club, cabal, a guild, or union. Their strategy is not
fixed in their rule-book. Am I splitting hairs? Yes, of course, but the point remains, there can be no such "oversight by meth cooks".
Unfortunately, the substance is one that destroys many lives - and unfortunately, there is absolutely nothing you can do to stop it. The bottom line
is the substance is a construction of three atoms of carbon, one atom of amine, and the benzene ring. The situation is similar to American prohibition
in the 1920's, which failed for no other reason than because the preparation (of ethyl alcohol) is to let sugar-water rot. Though more
involved, the cooks' ingredients and their plausible combinations are potentially infinite given the simplicity of the desired molecule! If more
citizens, or lawmakers, were aware of this simple conclusion, we could see a more benign technique for dealing with those souls. These situations are
not fully analogous - but organized crime found other business, as far as we know, though having flourished it can not be eradicated, and poisonous
contaminants in alcohol cause less of a human toll (for better or worse).
I hesitate to provide concrete examples, but a vague one illustrates. Direct CH functionalization is a technique in chemistry. It may be possible to
attach acetone, or even isopropyl amine itself directly to benzene. Phenylalanine, which can probably be cleaved to phenyl acetic acid, is present in
some plants and animals. See here, the principle is immutable: simple product means a diversity of practical routes: the unenforcable laws breed
contempt for the law as a whole, and for society: contempt for law and society causes social unrest, and benefits 1. the owners of prisons and
attached industries such as manufacturers of supplies, builders, iron smiths specialized in shackles, and law enforcement (if viewed as an industry:
sure, well intentioned as a whole, but economists, entrepreneurs etc. probably slip in.) and 2. the rich, fearing pitchforks of the educated and
otherwise capable, who would rather distract and dazzle the aspiring communists with crime, and feed them into what is unlikely to become in America,
but was, in the Soviet Union under Stalin a system of slave labor - from what I have read the result of an irreproachable Party, censorship, lack of
transparency, and poor education of the liberated peasants.
[Edited on 26-5-2015 by Morkva]
http://www.carrotmuseum.co.uk/falcarinol.html
“Science is the ultimate pornography, analytic activity whose main aim is to isolate objects or events from their contexts in time and space. This
obsession with the specific activity of quantified functions is what science shares with pornography.”
- J.G. Ballard, The Atrocity Exhibition
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zed
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Hnuh? Acetonitrile isn't a hard get. And, while Benzyl Chloride isn't fun to work with, it isn't hard to use it in a Grignard. Of more concern,
would be comments made about the procedure, by my erstwhile buddy Dr. Death..."Nasty" and "Miserable", come to mind.
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CuReUS
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it isn't hard to get,but it isn't cheap either
| Quote: | | And, while Benzyl Chloride isn't fun to work with, it isn't hard to use it in a Grignard. |
true,but from where do you plan to get Mg turnings for the grignard.DEA has already put it on the watchlist
| Quote: | | Of more concern, would be comments made about the procedure, by my erstwhile buddy Dr. Death..."Nasty" and "Miserable", come to mind.
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interesting character,I wonder who he is ?
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zed
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I'm not saying. It is unlikely, but possible, that Dr.Death has survived these many years, since our last encounter. If so, I'm disinclined to cause
trouble for him.
Can't get Mg turnings? Find another hobby.
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byko3y
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http://www.ebay.com/bhp/magnesium-anode
And I would be really glad if someone have tested the acetonitrile preparation. Without ussage of inorganic cyanides, of course.
I'm sure chinese could make acetonitrile for price not higher than 5$ per 1L. The reason why it's so costly is because you are not making it. I'm
talking to everybody here who thinks acetonitrile is costly.
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karlos³
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Some computer parts are made of pure Mg, did you really meant to say Mg turnings are hard to get ANYwhere?? I cant think of much else that is nearly
as easy to get than magnesium...
Acetonitrile in my country costs about 30€ per liter, and its analytical grade, and that from a reseller(so a bit more expensive).
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byko3y
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30$ is relatively expensive for a solvent. I would be glad to see some success storries about acetonitrile and pyridine preparation, but for some
reason I don't see even failures.
The life of many home chemists would be more peacefull if they had some well-developed protocols. And nowadays those, who actually could develop the
synthesis, just don't care.
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CuReUS
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I have a few questions that have been bothering me
1.In total synthesis 2,strike describes the conversion of safrole to the bromo derivative by reacting the alkene with HBr(from
NaBr+H2SO4) at reflux.
won't the HBr or H2SO4 cleave the MD ether ?
2.Suppose someone does a formylation reaction on catecol to make the corresponding benzaldehyde.The next step would be to make the MD bridge using DCM
or DBM.all the methods I have seen use strong bases at high temp.Isn't there a chance of a cannizaro reaction.
3.I found out that safrole is carcinogenic.How were people mad enough to deliberately ingest a cancer causing substance(I guess MDMA wouldn't have
been carcinogenic,but still.)
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Scr0t
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| Quote: Originally posted by CuReUS |
The next step would be to make the MD bridge using DCM or DBM.all the methods I have seen use strong bases at high temp. |
MeI2 in DMSO at ~80°C with K2CO3 as the base works well enough.
| Quote: Originally posted by CuReUS |
I found out that safrole is carcinogenic.How were people mad enough to deliberately ingest a cancer causing substance(I guess MDMA wouldn't have been
carcinogenic,but still.) |
Maybe they didn't know.
There's all sorts of carcinogenic compounds naturally occurring in our diet or are formed during its preparation e.g. acrylamide in fried foods.
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CuReUS
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| Quote: | | MeI2 in DMSO at ~80°C with K2CO3 as the base works well enough. |
are you talking about this
http://www.sciencemadness.org/talk/viewthread.php?tid=11786#...
| Quote: | | Maybe they didn't know. |
Its not a recent finding
| Quote: | | In 1960, the FDA banned the food use of safrole -- the main component in sassafras root bark -- when the volatile compound was found to cause cancer
in animals. |
from http://articles.latimes.com/2005/feb/14/health/he-supp14
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Scr0t
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No, something I tried when making myristicinaldehyde.
| Quote: |
Its not a recent finding
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Yeah, I know. Since you didn't say who or when these "people" were it seemed like an adequate response.
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