Alkynes drawing

Problem 6.17. An alternative mechanism for the [5 + 2] cycloaddition begins with coordination of the Rh(I) to the vinyl group and puts the homoallylic rearrangement before coupling to the alkyne. Draw this mechanism. 

The product of the reaction between the l-bromo-3-hexyne and lithium dieth-ylcuprate is an alkyne. Draw it. Is there anything in the IR that would allow one to distinguish the starting alkyne and the product alkyne How about the proton NMR How about information that can be obtained from the mass spectrum ... 

For each of the following alkynes, draw the products of (1) the acid-catalyzed addition of water (mercuric ion is added for part a) and (2) hyi oboration-oxidation a. 1-butyne b. 2-butyne c. 2-pentyne... 

Write the lUPAC names and formulas for alkenes and alkynes draw the condensed structural formulas for the monomers that form a polymer. 

The first step in the addition of an electrophile such as HBr to an alkyne involves protonation and subsequent formation of an intermediate vinyl cation. Where does propyne protonate Compare energies of 1-methylvinyl and 2-methylvinyl cations. Which is more stable Why Measure CC bond distance in the more stable cation. Does the cation incorporate a full triple bond (as in propyne) or a double bond (as in propene). Examine atomic charges and electrostatic potential maps to locate the positive charge in the two cations. Is the more stable ion the one in which the charge is better delocalized Use the charges together with information about the ions geometry to draw Lewis structures (or a series of Lewis structures) for 1-methylvinyl and 2-methylvinyl cations. 

Problem 8.2 There are seven isomeric alkynes with the formula Draw and name them. 

Draw Lewis structures of the following molecules and identify each as an alkane, alkene, or alkyne (a) CH3CCCH3 ... 

In this section, you reviewed how to name and draw alkanes, alkenes, and alkynes. You also learned how to name aromatic hydrocarbons. The names of all the other organic compounds you will encounter in this unit are based on the names of hydrocarbons. In the next section, you will learn about organic compounds that have single bonds to halogen atoms, oxygen atoms, and nitrogen atoms. 

In this review, well-defined metal-containing PAEs are described whose primary structure is represented by one of the schematic drawings A-C and E shown in Fig. 2. In contrast to the structures shown in the A-C systems, E has a conjugated phenyleneethynylene with metal chelates as end groups. PAEs containing metal complex as side groups (D) have, up to now, not been described in the literature. The classes of compounds such as metal-bridged alkynes, the poly(metallayne)s, and polymer carbyne complexes (structures G and H) do not in fact represent PAEs. 

Due to the copious amount of recent literature pertaining to olefin CM, a comprehensive review would prove repetitive, as this reaction is now a widespread synthetic tool. Fortunately, numerous reviews are now readily available on this subject. This chapter therefore focuses on reports pertaining to important aspects in either the concept or the application of alkene CM. Allene, alkyne, and enyne CM reactions are not included within the scope of this review. Drawing from the examples discussed, a series of general guidelines toward constructing a desired olefin CM transformation will be presented. 

After compiling many results obtained in similar studies of different substrates (alkenes, dienes, alkynes and so on), the results cannot be correlated to draw definitive conclusions due to the wide variety of parameters that can influence the reaction (substrates, catalyst precursors, supports, pressure, temperature and so on) [9, 208-214]. This is maybe the main reason why there are no clear mechanistic explanations for this simple reaction, unlike homogeneous gold-catalyzed processes. 

Given an alkene, alkyne, or diene, and one of the following reagents, draw the structure of the product reagents acids such as HCI, HBr, HI, and H2S04 water in the presence of an acid catalyst halogens such as Br2 and Cl2 hydrogen and Pd, Pt or Ni. 

As a C=C triple bond is shorter and stronger than a C=C double bond, the alkene 71 and n should lie between the alkyne 71 and 7t energy levels. Applying rule 2, we then draw the erroneous conclusion that alkynes are always less reactive than alkenes.44 Where is the mistake ... 

It occurs with stereoselective formal addition of proton and carboxylate at C, and C4 carbon atoms with concomitant C-C, C-H, and C-O bond formation, giving (1 fc,3fc)-1,3-dionyl acetate as the only stereoisomer. This general reaction proceeds for a variety of alkynes and carboxylic acids and is favored by electron-with-drawing groups on arylacetylenes. 

Fig. 5. Ball and stick drawing of the W2(/i-CSiMe3 2(CH2SiMe3)4 f 2-C2(Ph)Me molecule. The carbon atoms of the alkyne C-4 and C-5 and the /i-CSiMe3 ligands, C-22 and C-27, and the two tungsten atoms lie in a plane.

Draw and name alkynes, cycloalkynes, and their derivatives. 

For each molecular formula, draw all the isomeric alkynes, and give their IUPAC names. Circle the acetylenic hydrogen of each terminal alkyne. 

Name alkynes and their derivatives, and draw correct structures when given their names. 

Notice that atoms 1-4 are drawn in a straight line. Alkynes are linear—draw them like that ... 

The alkyne is using its HOMO to attack the hUMO of the nitrile oxide (see Chapter 35 for an explanation). If the alkyne has an electron-with drawing group, mixtures of isomers are usually formed as the HOMO of the nitrile oxide also attacks the LUMO of the alkyne. 

Both double and triple bonds are multiple bonds. Therefore alkynes are unsaturated hydrocarbons, just as alkenes are. To name alkynes and draw their structures, you follow the same rules that you used for alkenes. The only difference is the suffix -yne, which you need to use when naming alkyne compounds. Also, remember to count the number of bonds for each carbon. An alkyne bond counts as three bonds. 

Identify, draw, and name at least two examples of each kind of hydrocarbon you studied alkanes, alkenes, alkynes, and cyclic hydrocarbons. 

Scheme 16. Formation of tungsten perethyl-Cp complexes (and modifications) from a tungstenacyclobutadiene complex and alkynes (37,81-84). The generalized reaction indicates the formation of different isomers (more than two are possible) when three or more different substituents R are present. The WfC BuXdmeJQj complex also reacts with alkynes to give bulky Cp derivatives (82) (dme = dimethoxyethane). Molecule drawings are schematic.

Scheme 17. Formation of supracyclopentadienyl derivatives from the alkylidyne moiety in the dimeric tantalum complex and alkynes (13). Drawings of molecules are schematic.

Name acyclic and cyclic alkenes and alkynes, and draw structures corresponding to names. 

The study of polynuclear cobalt-alkyne clusters has provided insight into the coordination, protection, and activation of the carbon-carbon triple bond. It is possible to draw analogies between alkynes coordinated to molecular species and those to surfaces. 

A. Alkynes can be made by dehydrohalogenation of vinylic halides in a reaction that is essentially an F.2 process. In studying the stereochemistry of this elimination, it was found that (Z)-2-chloro-2-butcnedioic acid reacts 50 times as fast as the corres()onding E isomer. What conclusion can you draw about the stereochemistry of eliminations in vinylic halides How does this result compare with eliminations of alkyl halides ... 

High yields of benzenes are formed from internal alkynes (and a few select terminal alkynes) upon heating in the presence of a soluble catalyst generated by combining Me3SiCl and Pd/C. Although neither the mechanism nor the structure of any active intermediate is known, the procedure is so simple operationally as to be the method of choice for symmetrical systems (equation 31)." Regioselectivity is mixed in the few instances reported it is impossible at this time to draw conclusions as to possible similarities with PdCb systems. 

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