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Author: Subject: Beginner - lack of confidence?
monolith
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[*] posted on 26-4-2012 at 18:19
Beginner - lack of confidence?


I've taken a year of general chemistry and a year of organic chemistry at university. My grades are "ok," but as I browse these forums and read about the synthetic accomplishments of other chemists, I feel like I know absolutely nothing -- I often have no idea how to predict reactions or the conditions under which they happen. Is this normal or am I exceptionally stupid?

For example, should a decent amateur chemist be able to recreate a synthetic pathway e.g. recreate the hydrazine synthesis as seen here without consulting an outside source (textbook, article, patent, etc.)?

As another example, I was reading up on nitric acid synthesis and I came across a suggestion to distill impure nitric acid in sulfuric acid because the latter will 'hold onto the water' and allow for a purer nitric acid vapor. How does one know this; is it something that an amateur chemist should be able to derive from first principles, or does it come from experimentation/memorization?
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[*] posted on 26-4-2012 at 19:43


we build on the foundations that have been growing since antiquity.

i do feel that much has been done and i just discover the procedure and follow it though....

true discoveries are far out... personal discoveries are found at every level.

I find doing an experiment is easy, analyzing the results of it take instruments and time, which cost money etc....


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[*] posted on 26-4-2012 at 20:21


Monolith, I am finishing up a year of organic chemistry myself. From an experimental point of view, reading these forums, and researching through scientific journal's has taught me exponentially more then the organic chemistry book has. In general organic chemistry books explain reaction mechanisms, theory, common reactions, properties/trends, etc. These are all important concepts to have in your working memory don't hear me wrong! However, the intuition and ability to plan an experiment are something I think that come only from experience, research, explicit planning, or lot's of trial and error. Perhaps a happy mix of the three.

Higher level organic chemistry (graduate student) texts will give more information about experimental set-ups and kinetic v.s. thermodynamic products, solvent effects, selective reagents, mathematical models, etc. I find it kind of befuddling that my text will mention say an o-alkylation reaction and not even give the tiniest hint of how to perform them other then 'polar aprotic solvent, follows SN2'. Then the lab text will say 'use inert atmosphere, don't make contact with the reagents', but never why an inert atmosphere is needed, etc. Then I'll read on-line of successful examples done in polar protic solvents, and there are more SN reactions then SN1 and SN2 :D.

Again I'm no expert but this is the jist of what I have/am experiencing. The knowledge to be gained never seems to end, unless the ego transcends the passion.

[Edited on 27-4-2012 by smaerd]




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Pyridinium
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[*] posted on 26-4-2012 at 21:19


Quote: Originally posted by monolith  
I've taken a year of general chemistry and a year of organic chemistry at university. My grades are "ok," but as I browse these forums and read about the synthetic accomplishments of other chemists, I feel like I know absolutely nothing -- I often have no idea how to predict reactions or the conditions under which they happen. Is this normal or am I exceptionally stupid?

For example, should a decent amateur chemist be able to recreate a synthetic pathway e.g. recreate the hydrazine synthesis as seen here without consulting an outside source (textbook, article, patent, etc.)?

As another example, I was reading up on nitric acid synthesis and I came across a suggestion to distill impure nitric acid in sulfuric acid because the latter will 'hold onto the water' and allow for a purer nitric acid vapor. How does one know this; is it something that an amateur chemist should be able to derive from first principles, or does it come from experimentation/memorization?


You ask many good questions, and the best overall answer is 'experience'.

Synthetic chemistry is a great science unto itself, and some people have a talent for it, but at any rate, it all builds on existing knowledge. First principles do apply, but there's a limit; at some point you have to find out what's in the literature. Sometimes, ideas formulated on first principles ran into a roadblock that nobody foresaw.

What you're in effect describing is the difference between an experimentalist and a theorist; everybody would like to think they're good enough at chemistry that they can predict every reaction based on theory alone, but if that were the case, nobody would need to do experiments.

That said, being able to predict reactions is a skill that you can acquire at least partially. Experiment always trumps theory, but it's nice to look at a group of reactants and form an idea of the likely products. Some are better at it than others, but every one of us is always learning.




[Edited on 27-4-2012 by Pyridinium]
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AndersHoveland
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[*] posted on 26-4-2012 at 22:07


I found that undergraduate chemistry courses essentially teach nothing useful, only the basic foundations and familiarity with laboratory procedures.

The best way to become knowledgeable is to read, especially textbooks written before 1960. There is a very big difference between what is being taught now, and what was taught several decades ago.

The more you read about reactions, the better you will become at predicting what will happen. Whenever you see a reaction equation, ask yourself why the reaction happens. Chemistry can be a very complicated field, and even for the most experienced there is always plenty of new things to learn. Chemistry is not something one can become an expert at quickly, it takes many years. But eventually it will become second nature. People learn chemistry because they are interested in chemistry. Perhaps they saw exciting chemistry demonstrations when they were younger, or perhaps they are interested in the explosions.

I have been reading and learning about chemistry for about 12 years, starting at a very young age. It is a constant learning process. I never really "tried" to become knowledgeable, it was just something that happened along the way as I was reading things I was interested in. The internet has been one of the most helpful things. Just reading around in this forum one can learn much. Wikipedia is another basic source of information, although not always entirely reliable.

[Edited on 27-4-2012 by AndersHoveland]
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[*] posted on 27-4-2012 at 08:15


I disagree with Anders regarding choice of reading material & focusing on books written before 1960. Books written just 10 years ago are dated. For books older than that, proceed with caution and know the extent of their utility--and the significant advances in chemistry that have occurred since then.

Two books that I have found immensely useful in bridging the gap between sophomore O. Chem. and advanced coursework/experimental work are:

*"Introduction to Strategies for Organic Synthesis" by Laurie S. Starkey (Wiley, 2012): ISBN-10: 0470484098
*"The Art of Writing Reasonable Organic Reaction Mechanisms" by Robert Grossman (Springer, 2nd ed., 2002), ISBN-10: 0387954686
[This is an absolute classic and standard reading for those interested in O. Chem.]

These two books alone should give you a major edge in advanced courses. From there, you can move on to March's Advanced Organic Chemistry or Anslyn & Dougherty's Modern Physical Organic Chemistry. A good book on organometallic chemistry (Crabtree is good) will introduce you to modern synthetic strategies.

O Chem is a huge and exciting field. So it's natural to feel "dumber" as you gain a greater appreciation of it. The feeling is similar to standing near the ocean and contemplating your own size. You can never know everything but you can always find a niche in an exciting area of research.

[Edited on 4-27-12 by DDTea]




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[*] posted on 27-4-2012 at 11:31


It's interesting to read this. I'm in much the same position - fairly early in my undergraduate course, but often feeling somewhat out of my depth reading this forum despite doing well at university. That said, though, that is part of why chemistry is so incredible to me. Although we've actually learned a substantial amount of knowledge in absolute terms at this point, we've barely touched on even a tiny fraction of what's out there. Perhaps a bit daunting, also, but more exciting than daunting to me. I think the fun will come when, as DDTea somewhat touched on, we just happen to stumble on that one thing that we *really* love and are passionate about - even more so than the other chemistry we've learned.

Thanks for the book suggestions, DDTea, I'll check them out!

[Edited on 27-4-2012 by adamsium]
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rannyfash
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[*] posted on 27-4-2012 at 12:33


im 17 and hoping to become a synthetic chemist, i was left lots of books from my uncle who OD'd on a substance he had made and tested, i have all his notebooks and his notes on his substance which is pretty much a new class of organic molecule, i want to follow in his footsteps as he followed shulgin in his, but i have tried to memorise the organic chemistry books he had, and can work multiple routes to semi-simplistic compounds, but will need alot of work to actually get to where i want, read books, websites, scholar papers, ive seen some awesome sites which list every single mechinism, please dont have a rage at me because i sound obnoxious, i understand i do but i dont know how to phrase it any different way
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[*] posted on 27-4-2012 at 12:52


Quote: Originally posted by rannyfash  
im 17 and hoping to become a synthetic chemist, i was left lots of books from my uncle who OD'd on a substance he had made and tested, i have all his notebooks and his notes on his substance which is pretty much a new class of organic molecule, i want to follow in his footsteps as he followed shulgin in his, but i have tried to memorise the organic chemistry books he had, and can work multiple routes to semi-simplistic compounds, but will need alot of work to actually get to where i want, read books, websites, scholar papers, ive seen some awesome sites which list every single mechinism, please dont have a rage at me because i sound obnoxious, i understand i do but i dont know how to phrase it any different way


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[*] posted on 27-4-2012 at 13:23


Quote: Originally posted by rannyfash  
but i have tried to memorise the organic chemistry books he had, and can work multiple routes to semi-simplistic compounds, but will need alot of work to actually get to where i want, read books, websites, scholar papers, ive seen some awesome sites which list every single mechinism

Chemistry should not be memorized but rather understood by giving it a thorough thought. Mechanisms are a tool and a possible representation of how a reaction goes, there is no use memorizing them as they all have a safe and sound logic behind them. I would encourage you to take a look at Organic chemistry by Clayden, Greeves, Warren and Wothers. It shows, in an educative way, the basic logic behind organic chemistry.

A good way to rehearse would be to try and write a plausible mechanism for a reaction that one runs into in literature. Trying to figure out syntheses of simple (and possibly more complex) molecules is also a good idea. Drawing molecules in different angles, twisting them in 3D, using different projections and so on is also advised. Using lots and lots of scrap paper for scribbling is a way to go :)

When it comes to the original post of monolith:
Quote: Originally posted by monolith  
I often have no idea how to predict reactions or the conditions under which they happen. Is this normal or am I exceptionally stupid? For example, should a decent amateur chemist be able to recreate a synthetic pathway e.g. recreate the hydrazine synthesis as seen here without consulting an outside source (textbook, article, patent, etc.)?

In short the answer is no. At the uni we have had difficulties predicting all sorts of things! Without using literature to check what kinds of things have been tried out, what has worked, how well, in what conditions and so forth you are asking for trouble. To try all those things on your own would take up way too much time and money. Science is a collective thing, based on the work of others you can develop things further. Somewhere along the line it might well be that a great new reaction, catalyst etc. is found. Being able to do stuff without references is not in itself a sign of a great chemist. Being able to use resources in an innovative way, however, is.

[Edited on 27-4-2012 by kavu]
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[*] posted on 27-4-2012 at 15:40


Textbooks often contain an explicit or implicit oversimplified narrative of how things behave and how the behavior was historically conceptualized, tested, and placed in larger theoretical frameworks. DDTea has some excellent suggestions about ways to improve your mechanistic understanding. If you want to further contextualize and understand chemical research as a process, I suggest that you also read review articles covering different chemical topics, recent research papers about reaction mechanisms, and scientific histories of different topics in chemistry. If you want to play scientific historian yourself, you can also look at the evolution of certain concepts in chemistry simply by reading books/papers from different eras that mention the concept. For example, look at the long story of "nascent hydrogen."

Chemistry has reached the point that fairly accurate predictions of some properties/reactions can be made from first principles, using electronic structure calculations modeling quantum mechanics on computers. But the systems and properties that can be accurately treated this way are still a tiny subset of all chemical behavior. There is also an interesting philosophical trap in this approach: it requires a series of operations that is far in excess of what any human can keep in mind or even work through on paper in a lifetime. It is the map of the empire grown to cover the whole territory, as conceived by Jorge Luis Borges:

Quote:

On Exactitude in Science . . .

In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast Map was Useless, and not without some Pitilessness was it, that they delivered it up to the Inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography.


Computational methods have predictive power, but I would say that only those principles applicable by a human without computer aid enhance comprehension. It is much easier to narrate a reaction after the fact than to comprehend what will happen before the experiment is made. How much chemical behavior can be rendered both predictable and comprehensible? It's an open question, with tentative partial answers always in progress. There is much more behavior that comes from experiment and motivates theory than the other way around. You can conceive of chemistry as a vast ocean of special cases with a sparse archipelago of results that follow comprehensible rules.

[Edited on 4-27-2012 by Polverone]




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[*] posted on 27-4-2012 at 18:19


It's perfectly normal to feel overwhelmed on this forum at first. There are some very bright people here who may seem intimidating. But very few chemists pull information out of the blue, most people site their sources. Pulling info from other sources (as long as they are reputable) is not looked down upon, quite the contrary in fact.

As for finding good information on the interwebs, I think that a PDF search engine is a good place to start. Eventually you get to a certain point where a Google search or a search on Wikipedia doesn't yield enough info. Another good thing to do is to look at the references cited at the bottom of wikipedia pages. Many of those sources have great info far beyond the standards of Wikipedia itself. If you read these kinds of sources often and completely, I guarantee that basic chemistry will become second nature and you will not only be able to understand what happens during a reaction but also how and why.
http://www.findpdfdoc.com/

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[*] posted on 28-4-2012 at 02:37


I was reading up on nitric acid synthesis and I came across a suggestion to distill impure nitric acid in sulfuric acid because the latter will 'hold onto the water' and allow for a purer nitric acid vapor. How does one know this



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[*] posted on 28-4-2012 at 03:09


Quote: Originally posted by monolith  
For example, should a decent amateur chemist be able to recreate a synthetic pathway e.g. recreate the hydrazine synthesis as seen here without consulting an outside source (textbook, article, patent, etc.)?


No ...at least not easily. Many syntheses are highly specific in the reaction conditions because variations on the conditions can result in different products from the same reactants, where temperature, concentration, time of reaction, "residence time" for progressive reactions, and pH, presence or absence of catalysts, can have a profound effect on what is gotten and in what efficiency. Theoretical chemistry where everything appears to follow a certain predicted path does not necessarily translate directly to A + B = C or C + D as a realized process. You could have A + B = C + D + E + F in mixture of some proportions governed by conditions .....so then it becomes a practical process to identify by experiment what conditions best produce the desired product, where different products are possible.
It can get complicated how to best tune a process so that you produce the target compound which is desired. There is an aspect of trial and error involved in experiments aimed at devising a valid optimized synthesis from one more general scenario. A surprising variety of different products can be gotten from steering the reaction path for the same starting materials. There is a systematic methodology involved in experiments which is a kind of precision "toolmaking".
Quote:

As another example, I was reading up on nitric acid synthesis and I came across a suggestion to distill impure nitric acid in sulfuric acid because the latter will 'hold onto the water' and allow for a purer nitric acid vapor. How does one know this; is it something that an amateur chemist should be able to derive from first principles, or does it come from experimentation/memorization?

Understanding a property of concentrated sulfuric acid is that it has affinity for water to which it bonds and forms hydrates is basic knowledge, generally illustrated by the carbonization of sugar. But what is really being more generally valuable is getting the correct idea that formation of hydrates by a whole class of materials may make other things useful as dehydrating agents or dessicants also. So there could be (and actually are) alternative other materials than sulfuric acid useful for breaking the azeotrope of water and nitric acid, allowing the dilute acid to be concentrated by distillation. Sulfuric acid then is just one of the materials which can be useful as a tool material for the process toolmaker who is the chemist.

Edit: Now having addressed the second and third parts, I can return to the premise for your post asking the question:

Quote: Originally posted by monolith  
I've taken a year of general chemistry and a year of organic chemistry at university. My grades are "ok," but as I browse these forums and read about the synthetic accomplishments of other chemists, I feel like I know absolutely nothing -- I often have no idea how to predict reactions or the conditions under which they happen. Is this normal or am I exceptionally stupid?


No ...you are not stupid ...you are learning.....and part of that learning is learning how much you don't know, which should be humbling and generally is humbling to folks who have enough knowledge to correctly be humbled by the majestic complexity of the material world. Chemistry is an encompassing science like a huge net trawled through an ocean of unknowns about the material world and ultimately it is the study and science of materials themselves....which is pretty much the study of all that has "substance" and trying to comprehend the nature and behavior of matter at its higher levels of organization, and how that organizational structure is governed or modified is highly intuitive and abstract. Trying to understand the "stuff" from which the universe is made and how that stuff behaves in potentially reacting with other "stuff" is quite a challenge and should be properly humbling to anyone venturing into that area of "philosophy", and indeed it is "philosophy". Sometimes one may get the feeling that the entire universe and this entire life experience may be something like a little "golden book" handed to humanity as a reading and thinking primer which should understandably "light up the grid" of our synapses with plenty of activity trying to understand the sphere of everything that just is. Open a can of sardines and there may be some specimens there who were twice as smart as their peers now laid out side by side all in a neat row ....who never the less all still ended up in the same can and later on your cracker :D All is vanity !

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