Chemical Hints

JGC = Journal of General Chemistry (English translation of Zhurnal Obschei Kimii) 

JHC = Journal of Heterocyclic Chemistry JMC = Journal of Medicinal Chemistry JOC = Journal of Organic Chemistry JPS = Journal of Pharmaceutical Science LAC = Leibigs Annalen der Chemie MON = Monatshefte fur Chemie REC = Recueil Travaux Chemiques TET = Tetrahedron TL = Tetrahedron Letters 

Much useful information can be found in any lab text in organic chemistry such as that of Wiberg. 

Much information on chemicals, equipment, etc. can be obtained from the various trade journals and newspapers such as Chemical Marketing Reporter. Many companies sell used tabletting machines (e.g.. Union Std. Equip. Co. in New York and Chicago and Chemical and Process Mach. Corp. in New York). 

Shake the solution with an anhydrous salt such as MgSO, NbjSO, etc. andfilter out the salt. Solids can be dried by spreading on a filter paper at room temperature or drying in an oven at low heat. 

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E. HCA 53,50(1970) (see JMC 14,375(1971) or the following for other methods of reducing (IV)). 40 g (IV) in 90 ml methanol and 10 g aqueous 50% Raney-Ni (or substitute catalyst described in chemical hints section). Add dropwise over ten minutes with vigorous stirring a solution of 7.6 g NaBH4 in 25 ml 8N NaOH and cool to keep temperature at 50°. H2 evolution stops in about five minutes. Filter, wash with methanol and evaporate in vacuum to get mescaline (V0. 

Swinney H L, Argoul F, Arneodo A, Richetti P and Roux J-C 1987 Chemical chaos from hints to confirmation Acc. Chem. Res. 20 436-42... 

This example illustrates a subtle control of a chemical reaction by a delicate manipulation of tire stereochemical environment around a metal centre dictated by tire selection of tire ligands. This example hints at tire subtlety of nature s catalysts, tire enzymes, which are also typically stereochemically selective. Chiral catalysis is important in biology and in tire manufacture of chemicals to regulate biological functions, i.e., phannaceuticals. 

Troyan, J. E., series Hints for Plant Startup, Chemical Enginnering, Part I—Troubleshooting New Processes, November 14, 1960, p. 223 Part II—Troubleshooting New Equipment, March 20, 1961, p. 147 Part III—Pumps, Compressors, and Agitators, May 1, 1961, p. 91. 

Next, examine the equilibrium structure of acetamide (see also Chapter 16, Problem 8). Are the two NH protons in different chemical environments If so, would you expect interconversion to be easy or difficult Calculate the barrier to interconversion (via acetamide rotation transition state). Rationalize your result. Hint Examine the highest-occupied molecular orbital (HOMO) for both acetamide and its rotation transition state. Does the molecule incorporate a n bond. If so, is it disrupted upon rotation ... 

The Introduction furnishes hints for using the book and devotes special attention to the pecuharities of German chemical nomenclature. 

Perhaps the earliest hints of any numerical regularity among the atomic weights of the elements was discovered as early as 1817 by Dobereiner. He was the first to notice the existence of various groups of three elements, subsequently called triads, that showed chemical similarities. In addition, such elements displayed an important numerical relationship, namely that the equivalent weight, or atomic weight, of the middle element is the approximate mean of the values of the two flanking elements in the triad. 

What will now be proposed is that in addition to its role in ordering the elements, the quantity Z may be used to also affect a secondary classification of the elements, that is, their placement into vertical groups in the sense of the conventional periodic table. In proposing this idea, I make use of what was historically the earliest hint of chemical periodicity, namely, the existence of triads of elements [35]. 

Ice ages ended quickly. Processes that promote the increase of carbon dioxide in the atmosphere are positive feedbacks in ending an ice age. Is subglacial chemical weathering a positive or a negative feedback What circumstances would allow one to give the opposite answer (Hint ... 

Hint Write the partition functions for the atoms occupying step and terrace sites and equal their chemical potentials. 

It was generally assumed that it cannot and this became known as Dale s Law. During his studies on antidromic vasodilation he wrote (1935) When we are dealing with two different endings of the same sensory neuron, the one peripheral and concerned with vasodilation and the other at a central synapse, can we suppose that the discovery and identification of a chemical transmitter at axon reflex dilation would furnish a hint as to the nature of the transmission process at a central synapse. The possibility has at least some value as a stimulus to further experiments . 

There are thousands of commercially available additives of diverse chemical classes and with masses ranging from a few hundred to several thousand Daltons (cf. also Appendix II). Deformulation means reverse engineering, with subsequent analysis of each separated component. Product deformulation may hint towards the process of origin. Deformulation will combine several... 

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