Click chemistry was created by taking cues from how nature naturally reacts. 1 The goal of Sharpless and colleagues was to create a number of selective blocks that could be connected in many different ways with the ability to work in many various applications. 1 For a reaction to be defined as click chemistry: “the reaction must be modular, wide in scope, give very high yields, and generate only inoffensive by products that can be easily removed” and it must have undemanding reaction conditions. 1 The high thermodynamic driving force of the click reaction is the reason click reactions are able to achieve their specified characteristics.1 High selectivity for a lone product and a rapid completion of the reaction is another feature of click …show more content…
3 Bromine chain ends of the polymer were altered into an azide end group and then reacted with terminal alkynes to make diverse functional end groups. 3
All from resource 5____ High effiencey reaction , solved many problems in polymer science – concerning : a) poor degree of functionalization with many usual methods of polymerization concerning star- , graft-, and block copolymers, dendrimers, and on surfaces and interfaces, b) purification problems, c) incomplete reactions on surfaces and interfaces, d) harsh reaction conditions of conventional methods
Click reactins combines easily with controlled radical polymerization.(add resource) 11* the door to new polymer structures has been opened that were otherwise impossible.
To date the copper catalyzed cycloadditon type of click reaction is the most used. The azide/ alkyne reaction – metal catalyzed variation of Huisgen 1,3 dipolar cycloaddition reaction, “According to Sharpless : “a click reaction is defined by a gain of thermodynamic enthalpy of at least 20k•cal•mol-1 , this allows the possibility of high yielding, nearly substrate insensitive reaction.” Resource 5
Mechanism of Click
This week’s lab was the third and final step in a multi-step synthesis reaction. The starting material of this week was benzil and 1,3- diphenylacetone was added along with a strong base, KOH, to form the product tetraphenylcyclopentadienone. The product was confirmed to be tetraphenylcyclopentadienone based of the color of the product, the IR spectrum, and the mechanism of the reaction. The product of the reaction was a dark purple/black color, which corresponds to literature colors of tetraphenylcyclopentadienone. The tetraphenylcyclopentadienone product was a deep purple/black because of its absorption of all light wavelengths. The conjugated aromatic rings in the product create a delocalized pi electron system and the electrons are excited
In this lab 4-tert-butylcyclohexanone is reduced by sodium borohydride (NaBH4) to produce the cis and trans isomers of 4-tert-butylcyclohexanol. Since the starting material is a ketone, NaBH4 is strong enough to perform a reduction and lithium aluminum hydride is not needed. NaBH4 can attack the carbonyl group at an equatorial (cis) or axial (trans) position, making this reaction stereoselective. After the ketone is reduced by the metal-hydride, hydrochloric acid adds a proton to the negatively charged oxygen to make a hydroxyl group. The trans isomer is more abundant than the cis based on the results found in the experiment and the fact that the trans isomer is more stable; due to having the largest functional groups in equatorial positions.
Greta Christina eloquently puts into words something I know in theory, but can be hard to understand in practice in heterosexual relationships. In Are we having sex now or what? Christina details her record keeping of how many people she had sex with, and what she counted as sex. She talks about the limiting misconception of sex only being coitus, and other acts not “counting.” Christina writes of how when she started having sex with women her outdated system of what was sex and what was not sex was completely destroyed. By limiting sex to “penis in vagina,” Christina was discounting some of her favorite sexual experiances, and including ones she did not particularly enjoy.
Recently, several chemical synthetic cross-linkers have also been developed having superior cross-linking properties [27]. In particular, 4-aminoethanol-N-hydroxyethanyl-1,8- naphthalimide (AHN), a dual-hydroxyl naphthalimide derivative that have been utilized in fluorescent labeling and as the chemical cross-linking agent but with less toxicity [28].
Spinning is a process that involves forcing the liquefied polymer solution through a ‘die’ (small hole). The crystallinity of Kevlar Polymer strands, contributes to the unique strength and stiffness of the material. Kevlar is very similar to other common synthetic polymers, including Nylon, Teflon and Lycra. In all polated to strength. Aromatic refers to the Carbon atoms attached to a ring, and Amides refers to a group of Carbon, Nitrogen and Hydrogen atoms.
An elements¡¦ reaction to certain substances may be predicted by its placement on the Periodic Table of Elements. Across a period, an element on the left will react with more vigor than one on the right, of the same period. Vertically, as elements are sectioned into groups, the reaction of each element increases as you move down in the same group. With this in mind, the reactions of the substances involved in this experiment may be hypothesized, observed, and validated.
the iron ore to iron. In the other cases of metals the most common way
The synthesis of polymers starts with ethylene, (or ethene). Ethylene is obtained as a by-product of petrol refining from crude oil or by dehydration of ethanol. Ethylene molecules compose of two methylene units (CH2) linked together by a double carbon
Wood, A. (2005, August 10). Chemtura: Making a merger work. Chemical Week, 167, pp. 17-19.
SN2 reactions are described as bimolecular nucleophilic substitution reactions that occur in one concerted step without the formation of a carbocation intermediate. These reactions are performed most effectively in polar aprotic solvents such as acetone. The steric hindrance presented in the substrate is considered the most important factor due to the fact that the more steric hindrance there is around the halide, the harder it is for it to leave. The collected data for the SN2 reactions support this logic by showing that primary halides on substrates 4, 6, and 7 occurred within the first 5 minutes of the reaction. Substrates 6 and 7 were acted on immediately because 6 is allylic and 7 is benzylic, which creates an over lap of the pi bonds
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
The majority of the chemical reactions associated with diphenyl ether relate to the structures of the two phenyl rings of the organic compound due to the lack of reactivity typically associated with ethers. Ethers usually make excellent solvents due to the characteristic lack of reactivity. However, diphenyl ether participates in interesting reactions in spite of the stereotype. First and foremost, the formation of diphenyl ether primarily results from a deviation of Williamson Ether synthesis. These general reactions “involve an alkoxide that reacts with a primary haloalkane or a ...
German Chemist Hans von Pechmann first synthesized Polyethylene by accident in 1898 by heating diazomethane. His colleagues characterized the waxy substance polyethylene due to the fact that they recognized that it consisted of long ethene chains. It was then first industrially synthesized by accident in 1933 by applying extremely high pressure to ethylene and benzaldehyde. Over the years, development of polyethylene has increased due to the additions of catalyst. This makes ethylene polymerization possible at lower temperatures and pressures.1
J. Clayden, N. Greeves, S. Warren, P. Wothers. Organic Chemistry. 8th ed. 2007, Oxford University Press, p. 1186-1191.