Leaving groups, nucleophilic substitutions and elimination reactions

hey guys,

I have a good idea of what the answers, I just want to double check with others. 

1. which of the following are not good leaving groups?
- C2H5O-- Cl- ( i found that this is an ok LG)
- I- ( a very good leaving group)
- CH3CO2- ( This is also an ok leaving group)
- All of the above. I tried finding out information about the 1st option, but I am stuck. It is either down to option of or option 5.

2. Which nucleophilic subs. reaction would be unlikely to occur?
- HO- + CH3CH2-I------> CH3CH2-OH+I
- I- + CH3CH2-H----> CH3CH2-I + H-
- CH3S- + CH3-Br---------> CH3S-CH3 + Br-
- all of the above would be unilkely to occur.
I am stuck between the first 2 options, I is a good leaving group, but as far as H and OH put in the reactions I am confused on which to pick.

3. Regarding tert-butoxide as an E2 reaction, which statement is wrong.
- this base is more effective that ethoxide ion, becuase it (Ko-t- Bu) is more basic of the two.
- it is reactive in dimethyl sulfoxide that in tert-butyl alcohol.
- it will produce the more stable alkene.
- it favors E2 of Sn2
I think option 2 is wrong, but than again I think the third option is wrong as well.

4. To covert 2-bromobutane to 1-butene in the highest yeild. Which are the best reagents?
- KOH/H20
-KOH/CH3OH
-CH3ONa/CH3OH
-CH3CH2ONa/CH3CH2OH
-(CH3)3COK/(CH3)3COH

I know the first option is wrong, I think it is the 2nd one that deals with methonal.

5. Which of the following statments is/ are true of Sn2 reaction of (R)-2-bromobutane w/ hydroxide ion?
- Doubling the hydroxide ion concentration would double the rate of the reaction. ( assuming all other experimental conditions are unchanged.)
- The major product would be (s)-2-butanol.
- Doubling the concentration of (R)-2-bromobutane would double the rate of the reaction. (assuming all other experimental conditions are unchanged.)
- All of the above.
- Two of the above.

I think the third option is incorrect.

I figured out that question one is correct.

I have one more questions.

- The most specific term to describe the relationship between cis-3 hexene to trans- 3 hexene is:
1. stereoisomers
2. enatimoers
3. diastereomers
4. constitutional isomers.

I think is is constitutional isomers, but i always get confused with mirror images.

- The most specific term to describe the relationship between cis-3 hexene to trans- 3 hexene is:
1. stereoisomers
2. enatimoers
3. diastereomers

4. constitutional isomers. Well done! Cis and trans isomeres of 3-hexene are constitutional isomers. others(option 2 & 3 deal with their miror image (optical isomers).

can someone help me these 4 questions? by varying the answer.

2. Which nucleophilic subs. reaction would be unlikely to occur?
- HO- + CH3CH2-I------> CH3CH2-OH+I
- I- + CH3CH2-H----> CH3CH2-I + H-
- CH3S- + CH3-Br---------> CH3S-CH3 + Br-
- all of the above would be unilkely to occur. I am stuck between the first 2 options, I is a good leaving group, but as far as H and OH put in the reactions I am confused on which to pick.

3. Regarding tert-butoxide as an E2 reaction, which statement is wrong.
- this base is more effective that ethoxide ion, becuase it (Ko-t- Bu) is more basic of the two.
- it is reactive in dimethyl sulfoxide that in tert-butyl alcohol.
- it will produce the more stable alkene.
- it favors E2 of Sn2 I think option 2 is wrong, but than again I think the third option is wrong as well.

4. To covert 2-bromobutane to 1-butene in the highest yeild. Which are the best reagents?
- KOH/H20
-KOH/CH3OH
-CH3ONa/CH3OH
-CH3CH2ONa/CH3CH2OH
-(CH3)3COK/(CH3)3COH
I know the first option is wrong, I think it is the 2nd one that deals with methonal.

5. Which of the following statments is/ are true of Sn2 reaction of (R)-2-bromobutane w/ hydroxide ion?
- Doubling the hydroxide ion concentration would double the rate of the reaction. ( assuming all other experimental conditions are unchanged.)
- The major product would be (s)-2-butanol.
- Doubling the concentration of (R)-2-bromobutane would double the rate of the reaction. (assuming all other experimental conditions are unchanged.)
- All of the above.
- Two of the above.
I think the third option is incorrect.