alkynes

Question 1

general formula for alkynes

Answer 1

CnH2n-2

Question 1

how many elements of saturation for each triple bond

Answer 1

2

Question 2

physical properties of alkynes

Answer 2

nonpolar, insoluble in water
soluble in most organic solvents
boiling points are similar to alkanes of same size
less dense than water
up to four carbons; gas at room temp

Question 3

bond angle of acetylene

Answer 3

180

Question 4

is acetylide ion a strong nucleophile

Answer 4

yes

Question 5

how do you synthesize alkynes

Answer 5

nucleophilic attack by the acetylide ion on an unhindered alkyl halide

Question 6

what can acetylide ions also go through if the Sn2 reaction is not possible (hindered back side attack)

Answer 6

E2 reaction; can happen because acetylide ions are also strong bases

Question 7

what forms when nucleophile attacks carbonyl group

Answer 7

alkoxide ion; when alkoxide is deprotonated, an alcohol forms

Question 8

ketone

Answer 8

carbonyl group with two r groups

Question 9

aldehyde

Answer 9

carbonyl group with one r group

Question 10

formaldehyde

Answer 10

carbonyl group with no r group

Question 11

what is ethchlorvynol used for

Answer 11

used to cause drowsiness and induce sleep

Question 12

how is ethchlorovynol synthesized

Answer 12

addition of acetylide ion to carbonyl group

Question 13

how does synthesis of alkynes by elimination reactions work

Answer 13

removal of twowh molecules from HX from a vicinal or geminal dihalide

Question 14

when does triple bond migration occur

Answer 14

super basic conditions

Question 15

characteristics of pi addition reactions

Answer 15

pi bond becomes two sigma bonds
exothermic
one or two more molecules may add
syn or anti addition, cis or trans double bond, or single bond`

Question 16

catalytic hydrogenation

Answer 16

metal catalyst like pd, pt or ni is used, 2 hydrogen added to form alkane

Question 17

lindlar’s catalyst

Answer 17

allows the reaction to stop after the addition of one mole of H; produces cis alkene

Question 18

dissolving metal reduction

Answer 18

form trans alkene; anti stereochemistry; look for metal ammonia

Question 19

keto - enol tautomerization

Answer 19

carbon oxygen double bond is more stable than carbon carbon double bond; rearranges so that the carbon carbon doubel bond is replaced with the carbon oxygen double bond