java swt install and run

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add swt library into class path at [run configuration]

2012 의약계열 물리

31.
ㄱ. 원심력과 중력이 같으므로 합력은 0. 따라서 물체가 트랙을 미는 힘도 0. 그 반작용힘도 0
ㄴ.

$$m{v_0^2\over R} =m*g$$

CH3NaO

•   http://www.chemspider.com/Chemical-Structure.29033.html
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Sodium Methoxide

• ChemSpider ID: 29033
• Molecular Formula: CH₃NaO
• Average mass: 54.023701 Da
• Monoisotopic mass: 54.00816 Da
• Systematic name
  Sodium methanolate
• SMILES and InChIs

  SMILES:

  [Na+].[O-]C
  

  Std. InChI:

  InChI=1S/CH3O.Na/c1-2;/h1H3;/q-1;+1
  

  Std. InChIKey:

  WQDUMFSSJAZKTM-UHFFFAOYSA-N
• Cite this record

Dehydrohalogenation of alkyl halides in the presence of strong base (E2)

Dehydrohalogenation of alkyl halides in the presence of strong base (E2) is often accompanied by the formation of substitution (
SN2) products. The extent of competitive substitution depends on the structure of the alkyl halide. Primary alkyl halides give predominantly substitution products (the corresponding ether), secondary alkyl halides give predominantly elimination products, and tertiary alkyl halides give exclusively elimination products. For example, the reaction of 2-bromopropane with sodium ethoxide proceeds as follows:E2Fig1.jpg
          In general, for the reaction of alkyl halides with strong base:E2Fig2.jpg

Epoxide ring-opening reactions

8.6B: Epoxide ring-opening reactions - S_N1 vs. S_N2, regioselectivity, and stereoselectivity

The nonenzymatic ring-opening reactions of epoxides provide a nice overview of many of the concepts we have seen already in this chapter.  Ring-opening reactions can proceed by either S_N2 or S_N1 mechanisms, depending on the nature of the epoxide and on the reaction conditions.  If the epoxide is asymmetric, the structure of the product will vary according to which mechanism dominates.   When an asymmetric epoxide undergoes solvolysis in basic methanol, ring-opening occurs by an S_N2 mechanism, and the less substituted carbon is the site of nucleophilic attack, leading to what we will refer to as product B:

Conversely, when solvolysis occurs in acidic methanol, the reaction occurs by a mechanism with substantial S_N1 character, and the more substituted carbon is the site of attack. As a result, product A predominates.

These are both good examples of regioselective reactions.  In a regioselective reaction, two (or more) different constitutional isomers are possible as products, but one is formed preferentially (or sometimes exclusively).

Let us examine the basic, S_N2 case first. The leaving group is an alkoxide anion, because there is no acid available to protonate the oxygen prior to ring opening.  An alkoxide is a poor leaving group, and thus the ring is unlikely to open without a 'push' from the nucleophile.

The nucleophile itself is potent: a deprotonated, negatively charged methoxide ion.  When a nucleophilic substitution reaction involves a poor leaving group and a powerful nucleophile, it is very likely to proceed by an S_N2 mechanism.

What about the electrophile? There are two electrophilic carbons  in the epoxide, but the best target for the nucleophile in an S_N2 reaction is the carbon that is least hindered. This accounts for the observed regiochemical outcome.  Like in other S_N2 reactions, nucleophilic attack takes place from the backside, resulting in inversion at the electrophilic carbon.

Probably the best way to depict the acid-catalyzed epoxide ring-opening reaction is as a hybrid, or cross, between an S_N2 and S_N1 mechanism.  First, the oxygen is protonated, creating a good leaving group (step 1 below) . Then the carbon-oxygen bond begins to break (step 2) and positive charge begins to build up on the more substituted carbon (recall the discussion from section 8.4B about carbocation stability).

Unlike in an S_N1 reaction, the nucleophile attacks the electrophilic carbon (step 3) before a complete carbocation intermediate has a chance to form. 

Attack takes place preferentially from the backside (like in an S_N2 reaction) because the carbon-oxygen bond is still to some degree in place, and the oxygen blocks attack from the front side.  Notice, however, how the regiochemical outcome is different from the base-catalyzed reaction: in the acid-catalyzed process, the nucleophile attacks the more substituted carbon because it is this carbon that holds a greater degree of positive charge.

Standard Reduction Potentials

Standard Reduction Potentials

Potential Sorted

Alpha Sorted

Alpha Sorted

Potential Sorted

nernst equation

Standard Electrode Potentials

In an electrochemical cell, an electric potential is created between two dissimilar metals. This potential is a measure of the energy per unit charge which is available from the oxidation/reduction reactions to drive the reaction. It is customary to visualize the cell reaction in terms of two half-reactions, an oxidation half-reaction and a reduction half-reaction.

Reduced species -> oxidized species + ne-	Oxidation at anode
Oxidized species + ne- -> reduced species	Reduction at cathode

The cell potential (often called the electromotive force or emf) has a contribution from the anode which is a measure of its ability to lose electrons - it will be called its "oxidation potential". The cathode has a contribution based on its ability to gain electeons, its "reduction potential". The cell potential can then be written
E_cell = oxidation potential + reduction potential If we could tabulate the oxidation and reduction potentials of all available electrodes, then we could predict the cell potentials of voltaic cells created from any pair of electrodes. Actually, tabulating one or the other is sufficient, since the oxidation potential of a half-reaction is the negative of the reduction potential for the reverse of that reaction. Two main hurdles must be overcome to establish such a tabulation

1. The electrode potential cannot be determined in isolation, but in a reaction with some other electrode.
2. The electrode potential depends upon the concentrations of the substances, the temperature, and the pressure in the case of a gas electrode.

In practice, the first of these hurdles is overcome by measuring the potentials with respect to a standard hydrogen electrode. It is the nature of electric potential that the zero of potential is arbitrary; it is the difference in potential which has practical consequence. Tabulating all electrode potentials with respect to the same standard electrode provides a practical working framework for a wide range of calculations and predictions. The standard hydrogen electrode is assigned a potential of zero volts.
The second hurdle is overcome by choosing standard thermodynamic conditions for the measurement of the potentials. The standard electrode potentials are customarily determined at solute concentrations of 1 Molar, gas pressures of 1 atmosphere, and a standard temperature which is usually 25°C. The standard cell potential is denoted by a degree sign as a superscript.

E°Cell

Measured against standard hydroden electrode. Concentration 1 Molar Pressure 1 atmosphere Temperature 25°C

The example below shows some of the extreme values for standard cell potentials.

Cathode (Reduction) Half-Reaction	Standard Potential E° (volts)
Li+(aq) + e- -> Li(s)	-3.04
K+(aq) + e- -> K(s)	-2.92
Ca2+(aq) + 2e- -> Ca(s)	-2.76
Na+(aq) + e- -> Na(s)	-2.71
Zn2+(aq) + 2e- -> Zn(s)	-0.76
Cu2+(aq) + 2e- -> Cu(s)	0.34
O3(g) + 2H+(aq) + 2e- -> O2(g) + H2O(l)	2.07
F2(g) + 2e- -> 2F-(aq)	2.87

The values for the table entries are reduction potentials, so lithium at the top of the list has the most negative number, indicating that it is the strongest reducing agent. The strongest oxidizing agent is fluorine with the largest positive number for standard electrode potential. The link below takes you to a more extensive table.

Table of Standard Electrode Potentials

Useful applications of the standard electrode potentials include the following.

Strengths of oxidizing and reducing agents

Electrode potentials under non-standard conditions

Potentials for voltaic cells

Relationship to Gibbs free energy

Relationship to equilibrium constants