Alkynes Flashcards
ALKYNES
- contains??
- general formula
C≡C
Cn H2n-2
REAL LIFE EXAMPLE OF ALKYNES
used as fuel in oxyacetylene torches
acetylene
REAL LIFE EXAMPLE OF ALKYNES
a naturally occurring anti-viral, anti-fungal, and antibiotic compound
Thiarubine A
REAL LIFE EXAMPLE OF ALKYNES
contraceptive
norethynodrel
REAL LIFE EXAMPLE OF ALKYNES
antibiotic
mycomycin
REAL LIFE EXAMPLE OF ALKYNES
antifungal
terbinafine
REAL LIFE EXAMPLE OF ALKYNES
antiretroviral
efavirenz
REAL LIFE EXAMPLE OF ALKYNES
anticancer, and nematicide
phenylhepta-1,3,5-triyne
2 types of ALKYNES + their other name
+ meaning of their alt names
+ difference
- Terminal alkynes (monosubstituted) *C≡C is nasa pinakadulo so the C≡C as a whole only has 1 substituent attached
- Internal alkynes (disubstituted) *C≡C ay nasa gitna so the C≡C as a whole has 2 substituents, 1 per C, attached
PALATANDAAN in naming ALKYNES
in terms of:
- suffix
- parent chain (straight-chain) [2]
- -yne
- longest chain that passes thru BOTH C ATOMS in the triple bond (with the triple bond carbons having the lowest number)
- indicate position of triple bond before the parent name
ARANGE the ff in terms of stability and energy:
- alkenes
- 3 types of dienes
- 2 types of alkynes
MOST STABLE (lowest energy)
- conjugated dienes
- alkenes
- isolated dienes
- internal alkyne
- terminal alkyne
- cumulated dienes
LEAST STABLE (highest energy)
PHYSICAL PROPERTIES of ALKYNES
in general, are similar to ____ and ____
alkanes and alkenes
ALKYNES have slightly ______ BP & MP than alkenes
higher
WHICH will exhibit a higher BP and MP?
- linear
- branching
linear
*more branching = bp lowers
2 WAYS of preparing alkynes
- Industrial Preparation
- Laboratory Preparation
PREPARATION of ALKYNES - INDUSTRIAL
- 2 ways?
- what is formed?
ALKYNES formed from
- Carbides
- Methane
PREPARATION of ALKYNES - LABORATORY
- what is formed?
- ^^ how (2)?
alkynes from vicinal or geminal dihalides
PALATANDAAN in reactions in alkynes
mechanism is similar to alkenes, may exceptions or added info lang which is yung mga stated here
ALKYNES have a _____ C≡C due to?
- nucleophilic
- loosely held π electrons that can be donated to an electrophile
how MANY MOLES of reagent is necessary to convert an ALKYNE into a saturated product?
2 moles
saturated product = alkane
so 1 mole of reagent will break 1 π bond. since alkyne has 2 π bonds (triple bond), it would need 2 moles.
4 REACTIONS of ALKYNES
- Hydrogenation
- Electrophilic Addition
- Acetylide ion Formation
- Oxidative Cleavage
HYDROGENATION
- possible reagents (3)?
+ steriochemistry
H2 -> Lindlar’s Catalyst: syn addition alkene
Na or Li -> liq NH3: anti-addition alkene
2H2 -> Ni/Pt/Pd: tetra-substituted alkane
WHAT IF 1 mole of reagent lang ang rineact sa alkyne?
magiging alkene yung product, rather than alkane + 1 substituent lang ang ma s-substitute PER C ATOM in the C≡C
IF, 2 moles kasi ang gamit, 2 substituents ang ma s-substitute PER C ATOM sa C≡C
ELECTROPHILIC ADDITION - ADDITION OF HX
- what do you call the main product if 2 moles of HX is used as reagent?
- geminal dihalide (2 halogen atoms are attached to the same Carbon)
ELECTROPHILIC ADDITION - ADDITION OF X2
- stereochemistry?
- anti-addition pa rin kahit na 2 mols ang gamitin
DRAW the ff structures as requested by maam:
- Alkanes
- Alkenes
- Alkynes
ELECTROPHILIC ADDITION - HYDRATION
- reagents?
- what atoms attach to the C≡C?
- mechanism? + definition
+ study separate keto and enol
- H2SO4, H2O -> HgSO4
- H, O, and H
- KETO-ENOL TAUTOMERISM - rapid interconversion of enol & keto isomers
ELECTROPHILIC ADDITION - HYDRATION
- TERMINAL vs INTERNAL alkynes (what will their product be?)
+ which of the 2 follows markovnikov?
TERMINAL - 1 keto only (follows markovnikov)
INTERNAL - 1 keto (double bond O is in first C in C≡C) + 1 keto (double bond O is in second C in C≡C)
____ ALKYNES are more ___ than alkenes or alkanes due to a _____ ____ ____ character and a hybridization of ___
THIS MEANS THAT:
_____ %s = electrons are ___ to nucleus = more stable _____ charge = more ____
- TERMINAL
- acidic
- higher % s
- sp
- higher
- closer
- negative
- acidic
the _____ (or removal of substituent H+) of a TERMINAL alkyne leads to its _____ _____, an ____ ____, which is an excellent _____
- deprotonation
- conjugate base
- ACETYLIDE ANION
- nucleophile
the reaction, Acetylide Ion Formation, is only applicable to what type of ALKYNES?
terminal alkynes
ACETYLIDE ANION
- strength of basicity/acidity?
+ reason
STRONG BASE
bc it is a conjugate base of ACETYLENE (H-C≡C-H), which is a very weak acid
ACETYLIDE ION FORMATION
- study sample rxn
+ possible reagents (3) and their products
+ unique additional case? and its reagents
alcoholic AgNO3 -> Ag+
Na metal -> Na+ + H2
NaNH2 -> Na+ + NH3
- reaction with PRIMARY alkyl BROMIDES and IODIDES (Br & I attached to primary Carbon
- RBr / RI, Tetrahydrofuran (THF)
OXIDATIVE CLEAVAGE
- reagents?
- possible products (2)?
- O3 with Zn, H3O+
1.) 2 carboxylic acids (internal)
2.) 1 carboxylic acid + 1 CO2 (terminal)
TEST for analyzing ALKYNES
+ what type of alkynes is analyzed?
+ reagents
+ positive result
TOLLEN’S TEST for TERMINAL ALKYNES
- terminal
- ammoniacal or alcoholic AgNO3
- formation of gray ppt of silver acetylide + HNO3
