Sciencemadness Discussion Board

how was chemistry performed in the 1800's, prior to analytical equipment?

EmmisonJ - 9-4-2014 at 06:37

i'm just curious how chemists of the olden days were able to have any grasp at all on what it is that they're doing? back in the days when they didn't have libraries of reference papers/science journals at their disposal and before analytical equipment.

one example would be the fischer indole reaction in 1883. how did he have any idea of what he was really doing? IE: how did he know the reaction mechanism or what the product was?

i know that a lot of things were stumbled upon by accident but how were they not driving blind? if the purified end-product is odorless and generic (say, white powder) appearance, how do they have any idea of what happened during the reaction or what they have produced?

[Edited on 9-4-2014 by EmmisonJ]

Bert - 9-4-2014 at 11:46

An Internet search could point you towards some history of science related materials. Come back after and post some good links?

You could look in chemistry texts from a previous era.

There are even some 1800's texts available in the library-

Nicodem - 9-4-2014 at 13:06

You base your question on wrong assumptions.
Quote: Originally posted by EmmisonJ  
back in the days when they didn't have libraries of reference papers/science journals at their disposal and before analytical equipment.

Very wrong. Libraries exist since the ancient times. Just think of the library of Alexandria. By the 18th century several European countries already established national (or royal) scientific societies which, not only advanced the scientific method among the researchers, but also maintained the scientific libraries and exchanged their publications with other such societies. Some scientific journals go back to the early 19th century, or even the 18th. Before that, researchers published books. A lot was also going on on the level of peer-to-peer communication (letters and conferences).
Quote:
one example would be the fischer indole reaction in 1883. how did he have any idea of what he was really doing? IE: how did he know the reaction mechanism or what the product was?

The basic analytical tools also existed since the ancient times. For example, gravimetric and volumetric methods. Other are as old as the human race: organoleptic methods. Some are known since the middle ages, like thermometry and calorimetry. Some basic spectrometric methods and some reagent tests are also already a couple of centuries old. As far as Fischer goes, by that time the organic chemists already had a very powerful analytical tool: the elemental analysis which caused a rapid advance of the organic chemistry science.
Some tools, like chromatographic analytical methods and NMR spectroscopy - which the chemists of today would think absolutely obligatory - only came later. Yet, you would be surprised to find out what can be done by tedious work and by strictly adhering to the scientific method. Some very complex structures were determined correctly before NMR and XRD, mainly by hard laboratory work and ingenious approaches.
Quote:
i know that a lot of things were stumbled upon by accident but how were they not driving blind? if the purified end-product is odorless and generic (say, white powder) appearance, how do they have any idea of what happened during the reaction or what they have produced?

In the times before the invention of chromatographic analytical methods (TLC, HPLC, GC, etc.), they checked for purity by sequential recrystallizations and mp measurement (liquid products had to be first derivatized to solids). Identity was ascertained by mp measurements of admixtures with authentic standards (to check for mp depression absence). Each product was also derivatized and the derivative analysed to ascertain identity and purity (mp, elemental analysis, etc.). Independent synthesis was also commonly used to verify the proposed structures.

EmmisonJ - 11-4-2014 at 10:33

amazing reply nicodem, thanks for the explanation!

and thank you bert for the links, i'm taking a look at "A Manual of the Chemistry of the Carbon Compounds; or, Organic Chemistry" now. it's an old one from the 19th century that contains analytical methods.

DraconicAcid - 11-4-2014 at 10:45

I love reading old chem texts...the ones that describe iodine as a solid "with a distinctive taste", or recommend an experiment in which the student makes a dilute solution of prussic acid, and feeds a teaspoon of it to a cat.

BromicAcid - 11-4-2014 at 12:41

I remember reading Mr. Gergel's memoirs. He mentions when GC was introduced to the market as a package instrument. Previously purity in his lab was mostly based on boiling point and index of refraction for liquids but he found to his dismay that some of the compounds they had thought were pure was of poor quality via GC. What's worse is that there was not a GC in his lab, it was only after it went out to a customer that they got back to him and rode his case that the purity was lacking that he knew anything was up.

AJKOER - 14-6-2014 at 05:50

Examination of crystal structure is an old and still used method.

What I like about old chemistry texts is that it is mostly observation based chemistry. There was little theory, so some results contrary to theory would still be honestly reported. Not so much today as unexplained reaction results are not commented on much, in my opinion. For example, there are interesting reports of reactions promoted by 'nascent' hydrogen, which are now ascribed to other pathways, but one would be hard pressed to find either the reaction or an explanation in most modern chemistry books (perhaps embarassment when the actual causation is determined, or it is deemed off topic involving also physical or electrochemistry, or a demonstration that we just don't know everything?).

Perhaps less arrogance and more humility would serve science better.

Here is an interesting 2012 published article on nascent hydrogen, link http://www.researchgate.net/publication/221934434_Chemical_r... , titled "Chemical reduction of an aqueous suspension of graphene oxide by nascent hydrogen" by Viet Hung Pham, Hai Dinh Pham, ... in Journal of Materials Chemistry (Impact Factor: 5.97). 05/2012; DOI:10.1039/C2JM30562C to quote from the abstract:

"ABSTRACT One of the major challenges in the chemical reduction of graphene oxide is increasing the C/O atomic ratio of the chemically-converted graphene. In this paper, we report a simple and effective method to reduce aqueous suspensions of graphene oxide using nascent hydrogen generated in situ by the reaction between Al foil and HCl, Al foil and NaOH and Zn powder and NaOH. The nascent hydrogen-reduced graphene oxides (nHRGOs) were characterized by elemental analysis, UV-vis spectra, Raman spectra, X-ray photoelectron spectroscopy, thermogravimetric analysis and electrical conductive measurements. The reduction efficiency of graphene oxide strongly depended on the reaction medium and the rate of nascent hydrogen generation. The best nHRGO achieved a C/O atomic ratio greater than 21 and a bulk electrical conductivity as high as 12,500 S/m, corresponding to the nascent hydrogen generated from the reaction between Al foil and HCl. Since nascent hydrogen could be produced on a metal surface upon oxidation in solution, other metals with low standard reduction potentials, such as Mg, Mn, and Fe, can be applied to reduce graphene oxide."

Also, to quote from the paper's introduction:

"Nascent hydrogen is hydrogen at its “moment of birth” and is considered to be especially reactive.[24] Nascent hydrogen, denoted as H* or H (atomic hydrogen),[25] is naturally produced on a metal surface upon oxidation in solution or may be electrolytically generated by the reduction of hydrogen ions on certain cathode materials.[26] A common method to produce nascent hydrogen is the reaction of metals, such as Mg, Al, Fe or Zn with an acid, and [20, 25, 30, 35, 40, 45] amphoteric metals (Al, Zn) and their alloys (Devarda or Raney nickel) with alkali solution.[25-28] Although nascent hydrogen exists transiently, it lifetime is long enough to affect chemical reactions.[25-28] being monoatomic, nascent hydrogen is a powerful reducing agent, which is widely used to reduce arsenic or nitrobenzene,[25] chalcopyrite,[26] carbonyl compounds [27, 28] or to decolorize azo dyes. [29]"

References as cited in the paper, to quote:

20 X. Mei, J. Ouyang, Carbon, 2011, 49, 5389.
21 Y. Liu, Y. Li, M. Zhong, Y. Yang, Y. Wen, M. Wang, J. Mater. Chem., 2011, 21, 15449. 22 M. J. Fernandez-Merino, L. Guardia, J. I. Paredes, S. Villar-Rodil, P. Solis-Fernandez, A. Martinez-Alonso, J. M. D. Tascón, J. Phys. Chem. C, 2010, 114, 6426.
23 X. Zhou, J. Zhang, H. Wu, H. Yang, J. Zhang, S. Guo, J. Phys. Chem. C, 2011, 115, 11957.
24 F. Laborda, E. Bolea, M. T. Baranguan, J. R. Castillo, Spectochim. Acta. Part B, 2002, 57, 797.
25 W. B. Jensen, Bull. Hist. Chem., 1990, 6, 26.
26 J. C. Fuentes-Aceituno, G. Hydrometallurgy, 2008, 92, 26.
27 D. Papa, E. Schwenk, B. Whitman, J. Org. Chem., 1942, 7, 587.
28 E. Schwenk, D. Papa, B. Whitman, H. Ginsberg, J. Org. Chem., 1944, 9, 1.
29 R. Patel, S. Suresh, J. Hazard. Mater., 2006, 137, 1729.
30 Y. S. Su, Y. Xu, W. Zhang, J. Zhao, X. Tang, C. H. Tsai, L.-J. Li, Chem. Mater., 2009, 21, 5674.
31 W. Gao, L. B. Alemany, L. Ci, P. M. Ajayan, Nat. Chem., 2009, 1, 403. 65 8 9 70 75 80 85 90 95 T. Lapidus, F. M. Doyle, 100 105 110 Page 7 of 7Journal of Materials Chemistry Journal of Materials Chemistry Accepted Manuscript Downloaded by University of Ulsan on 21 March 2012 Published on 20 March 2012 on http://pubs.rsc.org | doi:10.1039/C2JM30562C View Online"

[Edited on 14-6-2014 by AJKOER]

arkoma - 14-6-2014 at 06:32

Newton's Principia was published in 1687! Not chemistry, but :o:o Occasionally the human race is "blessed" with an intellect more coherent than the tightest laser beam. Kekule especially comes to mind for me as an "hero" chemist from the 1800's but my current "hero" is Michael Faraday
Quote:
Although Faraday received little formal education, he was one of the most influential scientists in history.

As a chemist, Faraday discovered benzene, investigated the clathrate hydrate of chlorine, invented an early form of the Bunsen burner and the system of oxidation numbers, and popularised terminology such as anode, cathode, electrode, and ion.

Faraday was an excellent experimentalist who conveyed his ideas in clear and simple language; his mathematical abilities, however, did not extend as far as trigonometry or any but the simplest algebra.


Cool thread, actually.

forgottenpassword - 14-6-2014 at 06:33

Just as crystalline products were assumed to be pure by some, so today chromatographically pure products are assumed to be pure almost universally.

Many so-called pure compounds reported today have not been tested for purity on different column media. Something may elute as a single peak on one column, but be split into more peaks on a different column. Time constraints or simple ignorance of the need to check purity on a different column still leads to the erroneous reporting of 'pure' compounds today. The literature is full of, and greatly composed of such things.

Misidentification is by no means a thing of the past. Many things are routinely stated as fact, citing GC-MS on a single column, when a chromatographer would view such evidence as insufficient to constitute 'proof'.

[Edited on 14-6-2014 by forgottenpassword]

[Edited on 14-6-2014 by forgottenpassword]

cyanureeves - 14-6-2014 at 08:27

the development of modern chemistry by Aaron j.Ihde is a wonderful book that details alot of how chemical structures were percieved. chemists from different places without even knowing each other had the same notion with only slight variances.i love.love that book particularly the part that shows how atomical weights came about.the ratio in which elements were joined to oxygen or hydrogen although how abogadro came up with that crazy number is still all chinese to me.it's my opinion that matera does belong to man and is for man to decipher and master.i truly believe chemistry is God given.