Typical chemical shift assignments for ¹³C CP/MAS Solid-state NMR of natural organic materials

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Chemical Shift	Structure	Chemical Assignment
> 225 ppm	...	spinning sidebands
__Carbonyl__	_______________	_______________
225 ppm	C=C-C=O	ca.220 ppm quinoyl
.	C=O	205 ppm ketone (aliphatic); 190 ppm ketone and aldehyde
to	O-C=O	'>'= 175 ppm carboxylic acids (aliphatic)
.	N-C=O	='<' 174 ppm amidic, carboxylic esters (amino acids, aryl) 174.0 ppm acetyl, 172.0 ppm alpha-hydroxyl esters
160 ppm	(O)2-C=O	168 to 164 ppm carbonate
__Aryl______	_______________	_______________
165 ppm	aryl-O	158 to 135 ppm phenolic or aryl-ether
.	"	155 and 150 ppm - or - 153 and 148 ppm - lignins or tannins
.	p-hydroxyphenyl guaiacyl syringyl	152 to 156 ppm, (ortho aryl-H 115 ppm, others 130 ppm) 142 to 150 ppm (aryl-H 115 ppm, C-3 135 ppm) 150 to 155 and 135 to 138 ppm (aryl-H 106 to 113 ppm, C-3 135 ppm)
to	polyaromatic hydrocarbons (PAH)	130 (fresh char) to 135 ppm (coke) a broad set of resonances with a maximum around 132 ppm
.	olefinic	105 to 152 ppm, highly variable
.	"	129 ppm, natural cis-monounsaturated fatty acids 118, 134 ppm are also common olefinic peaks
105 ppm	cyano, nitrile	104 to 120 ppm
__Acetal____	_______________	_______________
110 ppm	O-CHn-O	anomeric carbon of saccharides
.	"	eg. Cellulose(I) 105.0, (II) 107.9,106.2, (ß form) 103.3 ppm
to	hemicellulose	ca.103 ppm
.	polysaccharides	101.5 to 100.0 ppm ß -glucosyl, a-xylopyranosyl and galactouronan C-1 carbons
92 ppm
94 ppm	breakthrough	often the transmitter is pulsed in the 13C frequency at about 90 to 95 ppm, and imperfect filtering may result in breakthru pulses most obvious here.
__O-Alkyl___	_______________	_______________
92 ppm	cellulose (I)	72, 74.17 ppm C-2,C-3 and C-5, 88 to 89.5 and 87.0 C-4
.	cellulose (II) C1-C5	73.5, 77, 89, 64 ppm
.	xtalline amorphous (inc. hemicellulose)	89.4 ppm 83.9 ppm - hemicelluloses are typically found in combination with acetate functional groups with resonances at 174 and 21.5 ppm
to	various C-6 carbon	68.1 ppm Cellulose(I), 64.5 to 65.0 ppm ß -glucosyl, ß -galactosyl 61.5 ppm amorphous celluloses, 17.6 ppm rhamnose
.	pectic-methoxyl	53.5 ppm
.	methoxyl CH3-O-	55 to 57 ppm typically a sharp resonance
52 ppm	methoxyl CH3-O-	60 to 62 ppm, methoxyl aryl ethers (eg. syringyl)
other	acetylenic	60 to 90 ppm highly variable
__X-Alkyl___	_______________	_______________
59 ppm	ß -C proteins	eg.42.6 pmm glycine, ca. 55 ppm typical in the solid-state and somewhat broadened due to 14N quadrupolar broadening
to	chitin	56 ppm, C-2 (N-aceytl uronic acid)
52 ppm
__Alkyl_____	_______________	_______________
46 ppm	>CH- (tertiary)	52 to 58 ppm
.	CR4 (quarternary)	36 to 48 ppm
to	CH and CH2	-10 to 42 ppm
.	CH2 typically	23, 30, 33, 39 ppm, (cyclic) 18.5 to 23.5 ppm
5 ppm	CH2-	18.4 ppm hexamethylbenzene (CH3)6C6 21.0 acetyl-(CH3)
______________	_______________	_______________
TMS	(CH3)4Si	TetraMethyl Silane (reference 0 ppm)
<0 ppm	CHn-X	Bromo- and Iodo- substituted alkyl (uncommon)
.	cyclopropane	-5 ppm

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